U.S. patent application number 10/914486 was filed with the patent office on 2005-01-27 for gastric retention dosage form having multiple layers.
Invention is credited to Edgren, David E., Jao, Francisco, Wong, Patrick S.L..
Application Number | 20050019409 10/914486 |
Document ID | / |
Family ID | 32993385 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050019409 |
Kind Code |
A1 |
Edgren, David E. ; et
al. |
January 27, 2005 |
Gastric retention dosage form having multiple layers
Abstract
The present invention is directed to a multilayered dosage form
which is adapted for retention in the stomach and useful for the
prolonged delivery of an active agent to a fluid environment of
use. The active agent dosage form is a multilayer core, often
bilayer, formed of polymer matrices that swell upon contact with
the fluids of the stomach. At least one layer of the multilayered
dosage form includes an active agent. A portion of the polymer
matrices are surrounded by a band of insoluble material that
prevents the covered portion of the polymer matrices from swelling
and provides a segment of the dosage form that is of sufficient
rigidity to withstand the contractions of the stomach and delay
expulsion of the dosage form from the stomach until substantially
all of the active agent has been dispensed.
Inventors: |
Edgren, David E.; (Los
Altos, CA) ; Jao, Francisco; (San Jose, CA) ;
Wong, Patrick S.L.; (Burlingame, CA) |
Correspondence
Address: |
Dewipat Incorporated
4606 FM 1960 WEST
SUITE 400
HOUSTON
TX
77069
US
|
Family ID: |
32993385 |
Appl. No.: |
10/914486 |
Filed: |
August 9, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10914486 |
Aug 9, 2004 |
|
|
|
09469399 |
Dec 22, 1999 |
|
|
|
6797283 |
|
|
|
|
60113560 |
Dec 23, 1998 |
|
|
|
Current U.S.
Class: |
424/472 |
Current CPC
Class: |
Y10S 424/06 20130101;
Y10S 514/836 20130101; Y10S 514/965 20130101; Y10S 514/866
20130101; A61K 9/0065 20130101; Y10S 514/884 20130101; Y10S 514/96
20130101; Y10S 514/909 20130101; Y10S 514/961 20130101 |
Class at
Publication: |
424/472 |
International
Class: |
A61K 009/24; A61K
009/00 |
Claims
What is claimed is:
1. An active agent dosage form adapted for gastric retention
comprising: (a) a first layer comprising a swellable, water-soluble
polymer; (b) a second layer comprising a therapeutically-effective
amount of an active agent, the second layer being laminated with
the first layer at a common surface, and (c) at least one band of
insoluble material circumscribing and binding together the first
layer and the second layer, the first layer being adapted to swell
in the stomach to facilitate retention of the dosage form in the
stomach over a prolonged period of time, wherein the release of the
active agent from the second layer is independent of the
composition of the first layer and occurs over a prolonged period
of time.
2. The active agent dosage form of claim 1 wherein the number
average molecular weight of the water-soluble polymer is between
about 100,000 and 20,000,000 grams per mole.
3. The active agent dosage form of claim 2 wherein the water
soluble polymer is polyethylene oxide, hydroxypropyl cellulose,
hydroxypropyl methyl cellulose, hydroxyethyl cellulose, sodium
carboxy methylcellulose, calcium carboxymethyl cellulose, methyl
cellulose, polyacrylic acid, maltodextrin, pre-gelatinized starch,
guar gum, sodium alginate, or polyvinyl alcohol.
4. The active agent dosage form of claim 1 wherein the second layer
comprises a hydroattractant selected from low-substituted
hydroxypropyl cellulose, microcrystalline cellulose, cross-linked
sodium or calcium carboxymethyl cellulose, cellulose fiber,
cross-linked polyvinyl pyrrolidone, cross-linked polyacrylic acid,
cross-linked Amberlite resin, alginates, colloidal
magnesium-aluminum silicate, corn starch granules, rice starch
granules, potato starch granules and sodium carboxymethyl starch,
sugars, sodium chloride, and the first layer optionally comprises a
hydroattractant selected from low-substituted hydroxypropyl
cellulose, microcrystalline cellulose, cross-linked sodium or
calcium carboxymethyl cellulose, cellulose fiber, cross-linked
polyvinyl pyrrolidone, cross-linked polyacrylic acid, cross-linked
Amberlite resin, alginates, colloidal magnesium-aluminum silicate,
corn starch granules, rice starch granules, potato starch granules,
sodium carboxymethyl starch, sugars and sodium chloride.
5. The active agent dosage form of claim 1 wherein the first layer
swells more rapidly and to a greater extent than does the second
layer.
6. The active agent dosage form of claim 5 wherein the active agent
is an antiviral, antimicrobial, antidiabetic, antihperglycemic,
hypoglycemic, antidepressant, antiobesity or antifungal active
agent.
7. The active agent dosage form of claim 4 wherein the weight
percent of the water soluble polymer in the second layer is 5 to
99.99 weight percent and weight percent of the hydroattractant in
the second layer is 0 to 60 weight percent.
8. The active agent dosage form of claim 1 wherein the prolonged
time period is at least 3 hours.
9. The active agent dosage form of claim 1 wherein the time period
is between about 6 to 12 hours.
10. The dosage form of claim 1 wherein the first layer comprises
polyethylene oxide having a number average molecular weight of at
least 100,000 grams per mole.
11. The dosage form of claim 10 wherein the active agent is an
antiviral, antimicrobial, antidiabetic, antihperglycemic,
hypoglycemic, antidepressant, antiobesity or antifungal active
agent.
12. The dosage form of claim 11 wherein the active agent is
acyclovir, ganciclovir, ritonavir, minocycline, cimetidine,
ranitidine, captopril, methyldopa, selegiline, minocycline,
fexofenadine, metformin, bupropion, orlistat or a pharmaceutically
acceptable salt thereof.
13. The dosage form of claim 10 wherein the active agent is
metformin or a pharmaceutically acceptable salt thereof.
14. The dosage dosage form of claim 1 wherein the second layer
comprises an active agent selected from the group consisting of
acyclovir, ganciclovir, ritonavir, metformin, bupropion, orlistat
and minocycline, and the second layer comprises a bioerodible
polymer, wherein the dosage form releases a therapeutically
effective amount of the active agent to the stomach of a subject
over at least a 3 hour period.
15. A method of treating a subject in need thereof with an active
agent that comprises administering to the subject a multilayered
dosage form adapted to be retained in the stomach over a prolonged
period of time, the dosage form comprising a first layer adapted to
swell in the stomach of the subject and retain the dosage form in
the stomach for a prolonged period of time, and a second layer
adapted to deliver to the subject an active agent at a variable
rate of delivery.
16. The method of claim 15 which comprises administering one or
more dosage forms to the subject in the fed state at the start of
each dosing period.
17. The method of claim 16 wherein the administration of the dosage
form occurs within one hour of the subject consuming food.
18. The dosage form of claim 1 comprising a gastric-emptying
delaying agent.
19. The dosage form of claim 18 wherein the gastric-emptying
delaying agent is selected from anticholonergic agents,
methylcellulose, guar gum, fats and fatty acids of 10-15 carbon
atoms.
20. The dosage form of claim 1 wherein the active agent comprises a
liquid, active agent formulation.
21. The dosage form of claim 20 wherein the liquid, active agent
formulation is sorbed into porous particles.
22. The dosage form of claim 21 wherein the porous particles are
calcium hydrogen phosphate or magnesium aluminometasilicate.
23. The dosage form of claim 1 wherein the dosage form comprises a
pH regulating agent.
24. The dosage form of claim 21 wherein the liquid, active agent
formulation comprises a pH regulating agent selected from organic
and inorganic acids and bases.
25. The dosage form of claim 21 wherein the liquid, active agent
formulation comprises a chelating agent.
Description
[0001] This application claims the priority of provisional
application No. 60/113,560, filed Dec. 23, 1998.
FIELD OF THE INVENTION
[0002] The present invention is related to the prolonged release of
an active agent from a dosage form. More particularly, it relates
to a multilayered active agent dosage form having a highly
swellable layer and a drug layer, the dosage form being adapted for
retention in the stomach for a prolonged period.
BACKGROUND OF THE INVENTION
[0003] Controlled release dosage forms that provide for prolonged
delivery of active agent formulations to the environment of use
have found application for increasing numbers of active agents.
However, with respect to pharmaceutical and veterinary active agent
formulations, there has been a need not only to provide for
prolonged delivery of the active agent over time, but also to
provide prolonged delivery of the active agent at a particular
location or locations in the environment of use, such as in the
stomach.
[0004] Certain active agents are absorbed primarily from the small
intestine. Generally, the time of passage of different particles
through the small intestine does not vary significantly, and
passage is generally independent of food intake and particle size.
Thus, active agent dissolved in liquid, solid active agent
dispersed in liquid and relatively larger delivery units of active
agent, such as microcapsules and the like, will traverse the length
of the small intestine in substantially the same time frame,
usually about 3-5 hours. For active agents that are not easily
absorbed by the small intestine or that do not dissolve readily,
the window for active agent absorption in the small intestine may
be too short to provide a desired therapeutic effect. This fact
often creates a need for frequent dosing of active agent in order
to provide and maintain adequate levels of active agent in blood
plasma. The need for frequent dosing presents compliance problems
and is often inconvenient for the user as well.
[0005] Since it has been found difficult to alter the transit time
of active agent through the small intestine, some emphasis has been
placed on attempting to control the transit time of active agents
in the stomach. Most active agents are not well absorbed in the
stomach, but even in those instances where the active agent is not
well absorbed, the continuous release of active agent in the
stomach over a prolonged time period will dispense active agent
over that same period of time to the small intestine where it can
be absorbed.
[0006] The physiological behavior of the stomach is usually
determined by whether it contains food or is empty. Food is mixed
and partially digested in the distal stomach (antrum). As the
stomach undergoes contractions, partially digested material is
discharged into the small intestine and non-digested material is
retropelled into the main part of the stomach for further
digestion. In the fed state, non-digested material is not generally
able to leave the stomach. At the end of a digestive period, the
stomach enters the fasting stage and begins a cycle called the
interdigestive myoelectric motor cycle or IMMC.
[0007] The IMMC can be considered to be divided into four phases:
(1) phase 1 is an approximately one hour period with no
contractions; (2) phase 2 is about a forty minute period of
intermittent potentials and contractions that increase in intensity
over time; (3) phase 3 is a relatively short period, generally
between about five to fifteen minutes, of intense contractions
(commonly called the "housekeeper wave") that completely empties
the stomach; and (4) phase 4 is a short transitory period between
the intense activity of phase 3 and the quiescence of phase 1. The
different phases move distally from the stomach to the terminal
ileum over an approximately two hour period as the cycle is
repeated. Since the cycle is interrupted by the receipt of food by
the stomach, it is possible to delay the emptying phase, phase 3,
by maintaining a fed state. However, it is not practical to
regularly maintain the fed state over a long period of time.
Consequently, a need exists for a delivery device that can remain
in the stomach for a significant period, whether in the fed or
fasted state, and deliver active agent to the stomach over a
prolonged period of time.
[0008] A variety of studies have been conducted in dog and in man
to determine sizes of objects that would be retained in the stomach
during the fed stage and also in the fasting stage when IMMC is
present. Khosla and Davis, International Journal of Pharmaceutics,
Vol. 62 (1990), pages R9-R11 have reported that a particle size
less that 2 mm generally results in emptying from the stomach of
the dog. Non-disintegrating tablets having sizes of 7, 11 and 13 mm
in diameter were emptied from the human stomach, but the larger
sized tablets tended to remain in the stomach longer than the small
sized tablets. Tablets larger than 11 mm tended to be emptied only
during the IMMC. Davis et al., Pharmaceutical Research, Vol. 8, No.
10 (1991) has described retention of radio-telemetry capsules
having a size of 25.times.8 mm in the stomach of human subjects
past phase 3 of the IMMC. Timmermans et al., Journal of
Pharmaceutical Sciences, Vol. 82, No. 8 (1993) has reported the
mean resting pyloric diameter in humans as 12.8.+-.7.0 mm.
Accordingly, it is important that gastric retentive delivery
vehicles are adapted to disintegrate, dissolve or erode to sizes
that permit eventual elimination of the vehicle without causing
gastric obstruction.
[0009] Various attempts to provide active agent delivery devices
that remain in the stomach for extended periods or time have been
described previously. For example, U.S. Pat. No. 4,851,232
describes a hydrogel reservoir containing tiny pills having a
active agent core surrounded by a wall controlling delivery of
active agent to the stomach. The hydrogel swells in the stomach to
facilitate retention of the active agent reservoir in the stomach
over time.
[0010] U.S. Pat. No. 4,871,548 describes a dosage form including a
mixture of low and high number average molecular weight
hydroxypropylmethylcellul- ose polymers and active agent that
swells when in the stomach.
[0011] U.S. Pat. No. 4,767,627 describes substantially planar
devices formed of bioerodible polymer including active agent that
may be compressed and folded for oral administration and then
released and unfolded in the stomach, where the devices are to be
retained over an extended period of time. The devices have a
longest diameter of between 1.6 and 5 cm. It is suggested that as
an alternative to incorporating the active agent into the device a
controlled release active agent module, mechanically or osmotically
driven, can be glued or tethered to the device.
[0012] U.S. Pat. No. 5,443,843 describes a plurality of
compressible retention arms and an attached controlled release
device which in the expanded form resists gastrointestinal transit.
The system can have a collar or a belt for receiving and holding a
active agent-containing, orally-administrable controlled release
device. In a fully expanded configuration for human use, the system
is described as having minimum and maximum dimensions of 2.5 and
6.0 centimeters, respectively.
[0013] U.S. Pat. No. 5,007,790 describes a sustained release active
agent dosage form in the form of a capsule or tablet that includes
a plurality of hydrophilic water-swellable, cross-linked polymer
particles that swell in the stomach to promote gastric retention
and permit gastric fluid to penetrate the particles to dissolve
active agent and deliver it to the stomach in the solution state.
The particles are indicated to retain their physical integrity over
the dosing period. Initially sized particles, indicated to be
preferably spherical, are disclosed to be in the range of 50 .mu.m
to 2 mm, swell to a size of about 3 mm. A plurality of particles
are packed into a capsule for administration to a patient.
[0014] U.S. Pat. No. 5,582,837 describes a dosage form similar to
that of U.S. Pat. No. 5,007,790, without the use of a cross-linked
hydrophilic polymer. The particles are described as slippery and
soft, preferably spherical, and having dimensions on the order of 6
to 18 mm in the swollen state. The particles can be packed into
capsules containing 7-25 spherical particles, depending on the
size, or formulated into tablets that contain from 2-25 spherical
particles.
[0015] The use of albumin-cross-linked polyvinylpyrrolidone
hydrogels to deliver flavin mononucleotide to dogs has been
described by Park et al. in Journal of Controlled Release, Vol.19
(1992) pages 131-134. The hydrogels were maintained in the stomachs
of dogs for extended periods, even in the fasted state. Gels with a
glassy core tended to remain in the stomach longer than hydrogels
without the glassy core. Control of the size of the core was
attempted by administration of water in the stomach. While it is
possible to control the dimensions of the hydrogel in the dry
state, controlling the size of the glassy core within the hydrogel
after administration to a subject by addition of water is not
suitable for fabrication of a dosage form that can routinely and
controllably be retained in the stomach of a subject over a
prolonged period of time.
[0016] While it is important that the delivery device be adapted-to
remain in the stomach for a prolonged period, it is also important
that the device deliver active agent in a controlled manner. Even
though control over the delivery of active agents that are released
from a highly swellable matrix as described in International
Application WO 99/07342, published Feb. 18, 1999, may be achieved
in many instances, a greater degree of control is possible when the
retention function of the dosage form and the drug delivery
function of the dosage form are addressed individually.
[0017] Delivery systems, such as those described below, are
representative of the many different systems have been suggested
for controlled delivery of active agents from a dosage form over a
prolonged period of time with no particular emphasis on retention
of the dosage form in the stomach for a prolonged period.
[0018] For example, U.S. Pat. No. 4,290,426 to Lusted et al
describes a cylindrical dispenser for releasing a beneficial agent
into a fluid environment at a rate that is governed by the fluid
induced relaxation of a polymeric agent contained within the
dispenser. The cylindrical dispenser includes an impermeable
container that has within it a reservoir and a passageway from the
reservoir to the exterior of the container. The reservoir contains
a polymer and a beneficial agent. The polymer imbibes fluid from
the environment and thereby undergoes relaxation, releasing the
beneficial agent from the device. The amount of agent released is
dependent on the rate of relaxation of the polymer over time.
[0019] Coated dosage forms have also been suggested for delivery of
a controlled amount of a beneficial agent over a prolonged period
of time. U.S. Pat. No. 5,256,440 describes a process for producing
a film coated dosage form. A continuous groove is inscribed in a
dosage form core. A latex film is coated onto the core, the groove
defining a fixed zone and a detachable zone for the film. The
detachable portion of the latex film detaches when it is exposed to
the environment of use, thereby exposing a discrete portion of the
dosage form core surface. The remainder of the film remains
attached to the dosage form core. The exposed portion of the dosage
form surface erodes and releases active agent to the environment of
use.
[0020] Coated tablets for constant and prolonged active agent
release are described by Conte et al in J. Controlled Release, Vol.
26, (1993) pages 39-47. These GEOMATRIX.RTM. Systems are swellable
matrices that are coated or tableted with polymeric barrier layers.
Release performances of the systems are modulated as a result of
the reduction of the releasing surface exposed to the dissolution
medium by the polymeric barrier layer coatings. As the extent of
coating of the system's surface is increased, the release kinetics
of the system shift toward constant release. These systems are
further described in U.S. Pat. No. 4,839,177 to Colombo et al.
[0021] U.S. Pat. No. 5,780,057 describes a one or two layered
tablet where at least one of the layers swells by contact with
biological fluids to promote retention of the tablet in the stomach
where the active ingredient may be slowly released. The description
indicates that at least one of the layers acts as a barrier for a
predetermined period of time to the active agent that is contained
one of the other layers.
[0022] U.S. Pat. No. 5,534,263, which is incorporated herein by
reference, describes a dosage form useful for the prolonged
delivery of an active agent formulation in the form of a matrix
having two or more insoluble bands on the surface of the matrix.
The exposed surfaces of the matrix erode in a manner that creates
additional surface areas to provide for prolonged release of an
active agent formulation with determined release profiles. That
patent is not concerned with dosage forms that are retained in the
stomach for a prolonged period of time.
[0023] Additional oral, controlled-release dosage forms include
elementary osmotic pumps, such as those described in U.S. Pat. No.
3,845,770, mini-osmotic pumps such as those described in U.S. Pat.
Nos. 3,995,631, 4,034,756 and 4,111,202, and multi-chamber osmotic
systems referred to as push-pull, push-melt and push-stick osmotic
pumps, such as those described in U.S. Pat. Nos. 4,320,759,
4,327,725, 4,449,983, 4,765, 989, 4,892,778, 4,940,465, 4,915,949
and 5,126,142, all of which are incorporated herein by
reference.
[0024] Administration of acyclovir by sipped solution over a
four-hour period has been described in Br. J. clin. Pharmac., 21,
459-462 (1986) to achieve an increased contact time with the human
stomach and the gastrointestinal tract. The total amount of
acyclovir absorbed was increased over that observed with
administration of acyclovir tablets. However, continuous oral
administration requiring the interaction of the patient is not what
would generally be considered suitable therapy. The influence of
food on gastric retention time and the absorption of acyclovir has
been reported in International Journal of Pharmaceutics, Vol. 38
(1987), pages 221-225. As reported there, compared to a lighter
meal, the heavier meal slowed the rate of gastric emptying,
prolonged small intestinal transit time and decreased absorption of
the active agent.
SUMMARY OF THE INVENTION
[0025] As can be observed in the above-referenced patents and
publications, devices have been described that provide for
prolonged delivery of an active agent and retention in the gastric
environment. However, there remains a continuing need for improved
systems for delivering an active agent to the gastric environment
over a prolonged period of time and in a reliable, controllable and
reproducible manner.
[0026] In one aspect, the invention comprises an active agent
dosage form adapted for gastric retention comprising (a) a first
layer comprising a swellable, water-soluble polymer, (b) a second
layer comprising a therapeutically-effective amount of an active
agent, the second layer being laminated with the first layer at a
common surface, and (c) at least one band of insoluble material
circumscribing and binding together the first layer and the second
layer, the first layer being adapted to swell in the stomach to
facilitate retention of the dosage form in the stomach over a
prolonged period of time. Preferably, the release of the active
agent from the second layer is independent of the composition of
the first layer and occurs over a prolonged period of time.
Examples of water soluble polymers include polyethylene oxide,
hydroxypropyl cellulose, hydroxypropyl methyl cellulose,
hydroxyethyl cellulose, sodium carboxy methylcellulose, calcium
carboxymethyl cellulose, methyl cellulose, polyacrylic acid,
maltodextrin, pregelatinized starch, guar gum, sodium alginate, or
polyvinyl alcohol, and most preferably high molecular weight
polyethylene oxide, e.g., Polyox.RTM. brand of polyethylene oxide
(Union Carbide Corporation, Danbury, Conn.). The first layer
preferably swells more rapidly and to a greater extent than does
the second layer. The first layer may be gel-like and exhibit a
slippery external surface.
[0027] In another aspect, the first or second layers of the
above-described dosage form comprises a hydroattractant selected
from low-substituted hydroxypropyl cellulose, microcrystalline
cellulose, cross-linked sodium or calcium carboxymethyl cellulose,
cellulose fiber, cross-linked polyvinyl pyrrolidone, cross-linked
polyacrylic acid, cross-linked Amberlite resin, alginates,
colloidal magnesium-aluminum silicate, corn starch granules, rice
starch granules, potato starch granules, pregelatinized starch,
sodium starch glycolates, guar gum, soybean fiber, psyllium husk
fiber, rice husk fiber, wheat fiber, alginic acid derivatives such
as sodium alginate and alginic acid, silicates such as bentonite,
colloidal magnesium and aluminum silicate (Veegum), gelatin,
cross-linked gelatin, sodium carboxymethyl starch, sugars and
sodium chloride.
[0028] In another aspect, the invention comprises the dosage form
as described above wherein the weight percent of the water soluble
polymer in the first layer is about 5 to 100 weight percent and
weight percent of the hydroattractant in the first layer is about 0
to 60 weight percent, and the weight percent of the water soluble
polymer in the second layer is about 5 to 95 weight percent and the
weight percent of the hydroattractant is about 5 to 70 weight
percent. The dosage form of the invention releases the active agent
over a prolonged period time of at least about 3 hours, more often
between 8 to 12 hours.
[0029] In still another aspect, the second layer may be formed of a
plurality of sublayers, each containing differing amounts of active
agent or different active agent or each being of different
thickness to provide active agent release profiles that vary with
time.
[0030] In a further aspect, the invention comprises a method of
treating a subject in need thereof with an active agent that
comprises administering to the subject a multilayered dosage form
adapted to be retained in the stomach over a prolonged period of
time, the dosage form comprising a first layer adapted to swell in
the stomach of the subject and retain the dosage form in the
stomach for a prolonged period of time, and a second layer adapted
to deliver to the subject an active agent at a variable rate of
delivery. The second layer may be comprised of multiple laminates,
each having a different active agent concentration per unit volume
and/or different thickness. The method may comprise administering
one or more dosage forms to the subject in the fed state at the
start of each dosing period, such as within one hour of the subject
consuming food.
DESCRIPTION OF THE DRAWINGS
[0031] The figures are not drawn to scale, but are set forth to
illustrate various embodiments of the invention. Like numbers refer
to like structures.
[0032] FIG. 1 is a schematic illustrating a dosage form of the
present invention;
[0033] FIG. 2 is a schematic of bilayer core of the dosage form
prior to completion of fabrication of the dosage form;
[0034] FIG. 3 is a completed dosage form of the invention;
[0035] FIG. 4 illustrates the dosage form of the invention soon
after administration where the retention layer of the dosage form
and the drug layer have swelled to substantially maximum
dimensions;
[0036] FIG. 5 illustrates the dosage form of the invention at an
intermediate time after administration where the retention layer
and the drug layer have eroded or dissolved in the stomach
environment, but at a stage where the retention layer is still
large enough to effectively maintain the dosage form in the
stomach;
[0037] FIG. 6 illustrates the dosage form at a later time than
illustrated in FIG. 5, when the retention layer has eroded or
dissolved to an extent that the dosage form may be expelled from
the stomach through the pylorous;
[0038] FIG. 7 illustrates a representative profiles of the
concentration of minocycline in the plasma of dogs from the bilayer
dosage form of the invention described in Example 8 and a
mono-system, also described in Example 8, in which the drug is
incorporated into the expandable layer to form a mono-system;
[0039] FIGS. 8A and 8B illustrate a representative in vitro release
rate profile and the corresponding cumulative release,
respectively, for the drug fexofenadine hydrochloride from a form
of the invention illustrated in FIGS. 1 in which the retention
layer is prepared from Polyox 303 and the drug layer is prepared
from Polyox WSR N-60K and low substituted
hydroxypropylcellulose;
[0040] FIGS. 9A and 9B illustrate a representative in vitro release
rate -profile and the corresponding cumulative release,
respectively, for the drug fexofenadine hydrochloride from a form
of the invention illustrated in FIGS. 1 in which the retention
layer is prepared from Polyox 303 and the drug layer is prepared
from Polyox WSR 301K and low substituted hydroxypropylcellulose;
and
[0041] FIG. 10 illustrates the dimensional changes as measured by
in vitro testing of the swelling of various formulations of the
high-swelling layer of the dosage forms of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0042] The present invention provides an active agent dosage form
that is retained in the stomach for a sustained period of time and
that is useful for the delivery of an active agent formulation to a
fluid environment of use over a prolonged period of time. In
International Application WO 99/07342, published Feb. 18, 1999, one
manner of providing such a dosage form is disclosed. However, the
particular active agent dosage form described therein is not always
suitable for all applications. It was discovered that there are
competing considerations when attempting to retain a dosage form in
the stomach of a subject for a prolonged period of time and at the
same time reliably deliver the active agent over that period.
[0043] Two such competing considerations are the requirement to
have the dosage form small enough for easy swallowing and yet have
the dosage form swell and become large enough after administration
to insure retention in the stomach for a prolonged period of time.
A second set of competing aspects is the need to incorporate enough
active agent into the dosage form so that it can be available for
release over the prolonged period of time while not detrimentally
affecting the ability of the dosage form to swell and increase in
size so as to be retained in the stomach for the requisite period
of time. Another consideration is to be able to control the rate of
release of the active agent from the dosage form without
compromising the rate at which the swollen polymer matrix is eroded
or dissolved in the stomach and consequently reduce the retention
time below acceptable levels.
[0044] Accordingly, it has been surprisingly discovered that the
dosage form of this invention may be fabricated with an individual
portion that does not contain active agent and an individual
portion that does contain active agent, those two portions being
laminated together and further joined by an insoluble band that
maintains the separate portions together during the prolonged
period in which the dosage form is retained in the stomach; that
the dosage form may be loaded with large amounts of active agent
when the clinical application requires; that the dosage form will
be retained in the stomach over a prolonged period; and that the
dosage form will be effective with separate portions having
different swelling, erosion and dissolution characteristics. The
particular improvements and characteristics comprising the
invention are described below.
Definitions
[0045] The phrase "prolonged period" or "prolonged period of time"
intends a time period that lasts for several hours to about 24
hours, usually up to about 12 hours, and often between about 3 and
14 hours, and most often at least 6 hours.
[0046] The phrase "prolonged delivery" intends a duration of
delivery extending over a time period that lasts for several hours
to about 24 hours, usually up to about 12 hours, and often between
about 3 and 14 hours, and most often at least 6 hours.
[0047] By "insoluble" is intended a material that will not
substantially dissolve in the environment of use during the
delivery period.
[0048] The term "active agent" refers to an agent, drug, compound
or other substance, or compositions and mixtures thereof, that
provide some pharmacologic, often beneficial, effect. Reference to
a specific active agent shall include where appropriate the active
agent and its pharmaceutically acceptable salts.
[0049] The term "polymer matrix" as used herein means a water
soluble, high molecular weight polymer and, optionally, a
hydroattractant in admixture therewith.
[0050] The term "active agent formulation" intends the active agent
or the active agent optionally in combination with pharmaceutically
acceptable carriers and additional inert ingredients.
[0051] The terms "adapted for gastric retention" or "gastric
retentive" mean, with respect to the dosage form of this invention,
that the dosage form will remain in the stomach of a subject for a
prolonged period of time.
[0052] The terms "rigid" and "semi-rigid" mean, with respect to a
portion of the polymer matrix as defined above, that such portion
will not swell and form a gel when initially contacted with gastric
fluid.
[0053] The term "bioerodible" intends a material that will, at
least in part, dissolve, degrade or erode in the fluid environment
of use.
[0054] The term "bioequivalent" intends, with respect to an active
agent dosage form of this invention, that there is greater than a
90% probability that the bioavailability of the active agent as
determined by standard methods is 80-125% of the defined dosage
form and that there is greater than a 90% probability that the
maximum blood plasma concentration and the minimum blood plasma
concentration of the active agent as measured by standard methods
is 80-125% of the defined dosage form.
[0055] The term "polymer" means a material formed from a single
polymer or a mixture of polymers.
[0056] The term "swellable" means, with respect to a polymer or a
polymer matrix, that the polymer or polymer matrix is capable of
imbibing fluid and expanding when in contact with fluid present in
the environment of use.
[0057] The terms "therapeutically effective" amount or rate refer
to the amount or rate of the active agent needed to effect the
desired pharmacologic, often beneficial, result.
[0058] The invention will be better understood with reference to
the drawings and the description herein.
[0059] FIG. 1 depicts one embodiment of the delivery device 10
according to the present invention. The delivery device or active
agent dosage form 10 comprises a first layer 12 of material that
swells upon imbibing fluid and a second layer 14, laminated at a
common surface 15. The first layer 12 conveniently is formed of a
highly swellable polymer which will initially swell upon imbibing
fluid and subsequently dissolve or erode after administration in
the stomach of a subject over a prolonged period of time. Second
layer 14 comprises a therapeutic agent, most often dispersed or
dissolved in a carrier. Second layer 14 may be formed of material
that swells to some extent in the stomach and which also will
dissolve or erode in the environment of use, i.e., primarily in the
stomach of the subject to whom the dosage form has been
administered. In most instances, the material forming first layer
12 will swell to a greater extent than that the material forming
second layer 14. A band 18 circumscribes the two layers 12 and 14
and maintains the two layers together during operation. This is
particularly important since the different swelling characteristics
of layers 12 and 14 may create a tendency toward delamination and
separation at the common surface 15. Band 18 typically is insoluble
and provides a certain degree of rigidity near the central portion
of the dosage form because of the inability of the first and second
layers to swell to any appreciable extent in the area under the
band. Optionally, a soluble coating 16 may be applied to the two
layers prior to the banding process to provide a smooth surface
that facilitates swallowing of the dosage form. Also, an optional
second, soluble coating (not shown) may be applied over the
completed dosage form to provide a continuously smooth external
surface.
[0060] Representative examples of the swellable polymer comprising
high molecular weight, water-soluble polymers useful for the
fabrication of first layer 12 are polyethylene oxide and cellulosic
polymer derivatives including hydroxypropyl cellulose,
hydroxypropyl methyl cellulose, hydroxyethyl cellulose, sodium
carboxy methylcellulose, calcium carboxymethyl cellulose, methyl
cellulose, as well as noncellulosics such as maltodextrin,
polyvinyls, polyvinyl alcohol, polyacrylic acids, alginates,
gelatin, natural gums, including guar, lightly crosslinked versions
of these polymers,starches, starch graft copolymers and the like.
The polymers generally have number average molecular weights over
50,000 grams per mole, such as between 50,000 and 10,000,000 grams
per mole and representative viscosities, e.g. for polyethylene
oxide in the range of 12-20,000 cps (5% aq, 25.degree. C., MW
100,000-900,000), 400-4000 cps (2% aq, 25.degree. C., MW
1,000,000-2,000,000) and 1500-15,000 cps (1% aq, 25.degree. C., MW
4,000,000-8,000,000) [Brookfield viscometer, rotational spindle];
for methylcellulose in the range of 1,500-18,000 cps (2% aq,
20.degree. C., MW 62,000-134,000) [Ubbelohde tube viscometer]; for
hydroxypropyl methylcellulose in the range of 4,000-100,000 cps (2%
aq, 20.degree. C., MW 88,000-242,000) [Ubbelohde tube viscometer];
for hydroxyethyl cellulose in the range of 75-400 cps (5% aq,
25.degree. C., MW 90,000-200,000), 400-6500 cps (2% aq, 25.degree.
C., MW 300,000-720,000) and 1500-5,000 cps (1% aq, 25.degree. C.,
MW 1,000,000-1,300,000) [Brookfield viscometer, rotational
spindle]; for guar about 5100 cps (1%) [Brookfield viscometer,
rotational spindle]; for poly(methyl vinyl ether/maleic anhydride)
in the range of 15 to greater than 200 cps (5% aq., MW
20,000-80,000) [Brookfield viscometer, rotational spindle]; for
polyvinyl alcohol in the range 27-65 cps (4% aq, 20.degree. C.
[Hoeppler falling ball method and 1100-1500 cps (10% aq, 25.degree.
C.) [Brookfield viscometer, rotational spindle; for sodium
carboxymethyl cellulose in the range of 25-50 cps (2% aq,
25.degree. C.) (MW 90,000) to about 2,500-6,000 cps (1% aq,
25.degree. C.) (MW 700,000) [Brookfield viscometer, rotational
spindle]; and for sodium polyacrylic acid 5000-80,000 (0.5% aq) (MW
750,000-4,000,000,000) [Brookfield viscometer, rotational spindle].
Polymers having molecular weights between 300,000 and 8,000,000
grams per mole are preferred, and those having molecular weights
between about 2,000,000 to 8,000,000 grams per mole are especially
preferred. Polyethylene oxide having a number average molecular
weight between about 5,000,000 to 8,000,000 grams per mole is most
especially preferred, e.g. Polyox 303 and Polyox 308. Also,
especially preferred are methylcellulose type/grade A15C, A4M, A18M
and hydroxypropyl methylcellulose type/grade K4M, K15M, K100M, E4M
and F4M (Dow Chemical Company); hydroxyethyl cellulose such as
Natrosol.RTM. HEC; hydroxypropyl cellulose such as Klucel (Grades
H, M, G, J, L, E-Aqualon Company); guar such as Supercol.RTM. Guar
U (Aqualon Company); pectin such as GENU Pectin (Aqualon Company);
carrageenan such as GENU Carrageenan (Aqualon Company); poly(methyl
vinyl ether/maleic anhydride) such as Gantrez.RTM. AN Copolymer
(AN-119, -139, -149, -169, -179, GAF Corporation); polyvinyl
alcohol such as Elvanole.RTM. 71-30, Elvanol.RTM. 85-80,
Elvanol.RTM. 55-65, Elvanol.RTM. 50-42 and Elvanol.RTM. HV
(DuPont); sodium carboxymethyl cellulose such as Aqualon cellulose
gum grade 7H4; polyacrylic acids such as Carpobole.RTM. resin
grades 934P, 940, 941, 971P, 974P, 980, 981, 1382, 2984, 5984, ETD
2001, ETD 2050, calcium polyacrylic acids such as Noveon.RTM. resin
grades AA-1, CA-1 and CA-2, and sodium polyacrylic acid (BF
Goodrich, Cleveland, Ohio).
[0061] Polymers that impart a surface lubricity to first layer 12
are especially preferred, and may be exemplified by polyethylene
oxides sold under the trademark Polyox, e.g. Polyox 303 and Polyox
308. The combination of surface lubricity, the gel-like nature of
the swollen polymer, the rigid section of the dosage form provided
by band 18 and the resulting non-swollen section of the dosage
form, and the particular size parameters of the swollen dosage form
all appear to contribute to the characteristic of the dosage form
to be retained in the stomach for a prolonged period of time.
[0062] First layer 12 may be formed with a hydroattractant
mixed-with the water soluble polymer. Representative
hydroattractants, that may be used are described below with regard
to the second layer 14. The use of a hydroattractant generally
facilitates rapid swelling of first layer 12 in the stomach and
generally provides a greater assurance that the dosage form will
attain a swollen size after administration that resists expulsion
through the pylorus. Fiberlike hydroattractants additionally serve
to impart a fiber reinforced gel structure.
[0063] Second layer 14 may also conveniently be formed of a polymer
base that swells to some extent to allow for erosion and
dissolution in the environment of use to facilitate release of the
active agent in a controlled fashion. Polymers of the classes
described for first layer 12 may be utilized. However, generally
polymer materials that do not swell to the same extent as those
employed in first layer 12 will be utilized. More limited swelling
allows for increased quantities of active agent to be loaded into
the second layer 14 than would otherwise be possible. Preferred
materials include the water soluble polymers such as described
above, particularly the polyethylene oxides having molecular
weights of between about 100,000 to 900,000 are preferred.
[0064] The second layer 14 may also preferentially include a
hydroattractant to draw in water from the environment of use to
facilitate release of active agent when the active agent is present
initially in a dry state. When active agent is provided in a
liquid, active agent formulation, as will be described later, the
use of a hydroattractant may be optional, since the carrier in
which the particles containing the liquid, active agent formulation
typically will dissolve or erode to allow the particles to be
released to the environment of use, and subsequently release active
agent at the absorption site.
[0065] Representative examples of hydroattractants are
water-insoluble polymers such as low substituted hydroxypropyl
cellulose, microcrystalline cellulose (Avicel), cross-linked sodium
or calcium carboxymethyl cellulose, cellulose fiber (Solka-Floc,
Arbocel or Elcema), cross-linked polyvinyl pyrrolidone
(Polyplasdone XL), cross-linked Amberlite resin, alginates
(Satialgine), colloidal magnesium-aluminum silicate (Veegum), corn
starch granules, rice starch granules, potato starch granules,
wheat starch granules, sodium carboxymethyl starch (Expotab,
Primojel), corn starch/acrylamide/sodium acrylate copolymer,
acrylamide/sodium acrylate copolymer and the like. A particularly
suitable hydroattractant is hydroxypropyl cellulose having a
hydroxypropyl content of between about 8-15 weight percent, and
preferably about 10-13 weight percent, such as that supplied as Low
Substituted Hydroxypropyl Cellulose grade 11 as manufactured by
Shin-Etsu Chemical Company, Ltd., Tokyo, Japan. Optionally,
non-polymeric water-soluble hydroattractants can be incorporated
into layer 12. These include sodium chloride, sugars such as
sorbitol, mannitol, glucose, maltose, sucrose, lactose, acids such
as citric acid, tartaric acid, succinic acid, gas-generating agents
such as sodiium or potassium bicarbonate which react with gastric
fluids to produce carbon dioxide gas, and the like.
[0066] As noted earlier, optionally, hydroattractants, such as
those described above, may be included in the first layer 12 as
well. Hydroxypropyl cellulose having a hydroxypropyl content of
between 8-15 weight percent is preferred, and most preferred are
those having a hydroxypropyl content of about 10-13 weight percent,
such as Low Substituted Hydroxypropyl Cellulose grade 11
exemplified above.
[0067] Typically, the water soluble, high molecular weight polymer
in the polymer matrix of the first layer 12 is present in from
about 5% to about 100% by weight based on the total weight of layer
12. Typically, the water soluble polymer forming layer 14 is
present in from about 5% to about 90% of the active agent
formulation layer 14, and the hydroattractant is present in from
about 5% to about 70% by weight based on the total weight of the
active agent formulation layer 14. The particular percentages will
be chosen to provide the desired retention time in the stomach and
the desired release profile of active agent. However, it is
presently preferred to have the polymer matrix forming layer 12
contain about 50% of a highly swellable, water soluble polymer, 25%
of cellulose fiber and 25% sodium chloride, and the polymer matrix
forming second layer 14 contain from about 10 weight percent to
about 50 weight percent of the water soluble, high molecular weight
polymer and from about 10 weight percent to about 60 weight percent
of the hydroattractant. Weight percentages of water soluble, high
molecular weight polymer in the range of 10 to 40 weight percent
and hydroattractant in the range of 25 to 35 in second layer 14 are
especially preferred, the remaining percentage being active agent
or an active agent composition.
[0068] Dosage form 10 is conveniently cylindrically shaped with
rounded ends that facilitate administration of the dosage form in
its non-swollen state. In FIG. 2, the device 10 is shown in
preparation, without the addition of an overcoat, prior to
application of the insoluble material or band 18 shown in FIG. 3.
The insoluble material exemplified as band 18, circumscribes a
portion of the outer surface of the dosage form 10, including both
layer 12 and layer 14. While a single band is illustrated in FIG.
3, additional bands can be utilized depending on the particular
application for which the device is being used. For ease of
illustration, optional coating 16 and any optional overcoat have
been omitted in FIGS. 2-6.
[0069] The band of insoluble material 18 is applied to the outer
surface of the layers 12 and 14. The insoluble material imparts
rigidity particularly to the gel-forming polymer matrix forming
layer 12 to manage gastric retention time and further control the
delivery profile of the active agent of interest from layer 14.
Band 18 typically exhibits low water permeability and will prevent
that portion of the polymer matrices which it surrounds from
imbibing fluid, thus substantially limiting any swelling of the
polymer matrix of layers 12 and 14 at that location. In addition,
given that the layers 12 and 14 often may be formed of different
materials having rates of swelling that tend to delaminate the
dosage form at the common surface 15, band 18 also serves to retain
the two layers together and maintain the integrity of the dosage
form 10 during most of its lifetime. The number, size, and
placement of the insoluble bands that are applied may be varied to
adjust the active agent delivery profile and the retention time in
the stomach. For example, bands 0.1 mm to about 12 mm in width,
preferably between about 0.5 and 8 mm, may be applied onto the
active agent formulation matrix surface. Further, between about 1
and 10 bands may be used, but generally between about 1 and 3 are
affixed to the bilayer core. The bands may be placed close together
(i.e., within about 0.5 mm of each other) or may be placed about 8
to 12 mm apart.
[0070] FIG. 4 illustrates dosage form 10 in its initial
configuration after it has imbibed fluid and swelled in those areas
not surrounded by band 18. Because of the low fluid impermeability
of band 18, the portion of dosage form 10 surrounded by band 18
does not appreciably imbibe fluid and the polymer in such portion
of the dosage form does not swell to any significant extent. FIG. 5
illustrates a sequential state of dosage form 10 after it has begun
to be eroded by or dissolve in the gastric fluid. FIG. 6
illustrates the dosage form after it has been substantially eroded
by gastric fluid and contractions of the stomach. Eventually,
dosage form 10 will be reduced to such a size as to enable it to be
expelled from the stomach.
[0071] The insoluble material comprising band(s) 18 may be any
material that is nontoxic, biologically inert, nonallergenic and
nonirritating to body tissue, that exhibits little impermeability
to liquids, and that maintains its physical and chemical integrity
in the environment of use for at least a portion of the dispensing
period. The bands may be formulated with neutral charge polymers
which are insoluble in gastric fluid or may be formulated wilth
anionic polymers which are insoluble in gastric fluid and dissolve
in intestinal fluid. The low liquid permeability of the insoluble
material serves to limit swelling of the polymer matrix in that
section of the polymer matrix that is surrounded by the band.
[0072] Insoluble materials from which the bands may be prepared
include, for example, polyethylene, polystyrene, ethylene-vinyl
acetate copolymers, polycaprolactone and Hytrel.RTM. polyester
elastomers (Du Pont). Additional banding materials include but are
not limited to polysaccharides, cellulosics, cellulose acetate,
cellulose acetate propionate, cellulose acetate phthalate,
cellulose acetate butyrate, cellulose acetate pseudolatex (such as
described in U.S. Pat. Nos. 4,931,285 and 5,024,842), ethyl
cellulose, ethyl cellulose pseudolatex (such as Surelease.RTM. as
supplied by Colorcon, West Point, Pa. or Aquacoat.TM. as supplied
by FMC Corporation, Philadelphia, Pa.), nitrocellulose, polylactic
acid, poly-glycolic acid, polylactide glycolide copolymers,
polycaprolactone, polyvinyl alcohol, polyvinyl acetate,
polyethylene vinylacetate, polyethylene teraphthalate,
polybutadiene styrene, polyisobutylene, polyisobutylene isoprene
copolymer, polyvinyl chloride, polyvinylidene chloride-vinyl
chloride copolymer, copolymers of acrylic acid and methacrylic acid
esters, methacrylic acid copolymers, copolymers of
methylmethacrylate and ethylacrylate, ammoniomethacrylate
copolymer, latex of acrylate esters (such as Eudragit.RTM. supplied
by RohmPharma, Weiterstadt, Germany), polypropylene, copolymers of
propylene oxide and ethylene oxide, propylene oxide ethylene oxide
block copolymers, ethylenevinyl alcohol copolymer, poly sulfone,
ethylene vinylalcohol copolymer, polyxylylenes, polyamides,
rubbers, such as styrenebutadiene, polyisobutylene and the like,
natural and synthetic waxes, paraffin, carnauba wax, petroleum wax,
white or yellow bees wax, castor wax, candelilla wax, rice bran
wax, microcrystalline wax, stearyl alcohol, cetyl alcohol, bleached
shellac, esterified shellac, chitin, chitosan, silicas,
polyalkoxysilanes, polydimethyl siloxane, polyethylene
glycol-silicone elastomers, crosslinked gelatin, zein,
electromagnetic irradiation crosslinked acrylics, silicones, or
polyesters, thermally crosslinked acrylics, silicones, or
polyesters, butadiene-styrene rubber, glycerol ester of partially
dimerized rosin, glycerol ester of partially hydrogenated wood
rosin, glycerol ester of tall oil rosin, glycerol ester of wood
rosin, pentaerythritol ester of partially hydrogenated wood rosin,
pentaerythritol ester of wood rosin, natural or synthetic terpene
resin and blends of the above.
[0073] The banding materials often are also formulated with
plasticizers, and optionally with wetting agents, surfactants,
opacifiers, colorants, flavorants, taste-masking agents, and the
like. Examples of typical plasticizers are as follows: polyhydric
alcohols, polyethylene glycol, glycerol, propylene glycol, acetate
esters, glycerol triacetate, triethyl citrate, acetyl triethyl
citrate, tributyl citrate, acetyl tributyl citrate, triacetin,
glycerides, acetylated monoglycerides, oils, mineral oil, castor
oil, PEG castor oil, and the like.
[0074] Referring again to the embodiment of the invention depicted
in FIG. 3, dosage form 10 in its non-swollen state has a length L1
and a maximum diameter D1. FIG. 4 shows dispensing device 10 after
having been placed in the stomach.
[0075] After swelling, the dosage form 10 has a length L2 and a
maximum diameter D2 measured at the widest part of the swollen
polymer matrices, as illustrated in FIG. 4. Generally, for human
applications the largest dimension of the device in the swollen
state equivalent to the diameter D2 should be greater than 7 mm,
preferably 10 mm or greater, and most preferably 13 mm or greater
during the period of residence in the stomach when active agent is
being dispensed. Since the active agent formulation is intended to
remain in the stomach for a prolonged period, the effective
diameter of the active agent dosage form when in its swollen state
in the stomach may have to be significantly larger than 13 mm, and
may extend to more that 50 mm or greater. Larger dosage forms may
be appropriate particularly when the polymer matrix is designed to
erode relatively rapidly over time in order to provide the required
delivery of active agent for therapeutic effect.
[0076] In contrast to the exposed segments of the swollen polymer
matrices, band 18 and the portion of the polymer matrices beneath
it do not swell significantly. Accordingly, that segment of the
dosage form surrounded by band 18 is maintained in a constrained
and more compressed, non-swollen state than the unbanded portion of
the matrices. Since band 18 does not take up an appreciable amount
of fluid from the stomach and swell, band 18 retains its
substantially rigid or semi-rigid form, and provides an element of
rigidity to the dosage form as a whole. While it is not entirely
clear how band 18 and the constrained segment of the polymer
matrices of layers 12 and 14 facilitate retention of the dosage
form in the stomach through housekeeping waves, it is thought that
the band reduces the rate of erosion of the polymer matrices, thus
maintaining a larger effective size of the dosage form and reducing
the chance for its expulsion from the stomach, for a longer period
of time than would otherwise occur if the band was not present.
Additionally, the presence of the band on the polymer matrices
provides a semi-rigid segment of the dosage form that appears to
permit the dosage form to be retropelled into the main area of the
stomach as a reaction to the stomach contractions rather than being
expelled by the housekeeping wave, as a less rigid gel would be
inclined to be.
[0077] For applications in animals other than humans, for example
in dogs, the maximum diameter should be greater than about 2 mm.
The maximum dimension for any particular dosage form will depend on
the particular application and animal in which the device is being
used. Such dimensions can be determined by those skilled in the art
in accordance with the teaching herein and the various patents and
publications noted herein and existing in the related art.
[0078] A practical consideration, particularly for oral
administration to humans, is that the initial size of the device be
such that it can be reasonably, comfortably swallowed. For human
oral applications, a preferred size of the device in its form prior
to administration to the stomach would be on the order of a size
000 capsule to a size 5 capsule. However, it is understood that
smaller or larger sizes could be used for particular applications
where necessary. Since the dosage forms of the invention may be
gel-forming, it may be desirable to wet the outer surface of the
dosage form immediately prior to the subject swallowing the dosage
form in order to provide a more slippery outer surface and promote
ease of swallowing. Alternatively, the bilayer core can be inserted
into a hard gelatin capsule prior to application of the band in
order to facilitate swallowing and also promote ease of manufacture
in applying and forming the bands. Upon entering the stomach, that
portion of the hard gelatin capsule that is not covered by the band
will dissolve, exposing the polymer matrices to fluid in the
stomach. As the polymers imbibe fluid, the dosage form will swell
in the exposed segments as previously described. The dosage form
typically is prepared to allow for swelling at a controlled rate,
particularly at a limited initial rate, so that the dosage form
does not swell inordinately during the swallowing process and
result in obstruction of the esophagus.
[0079] The configuration of the multilayer dosage form is selected
to achieve the delivery duration and gastric retention period
targeted for a particular drug. Generally, the bilayer compressed
tablet is fabricated such that the dimensions and proportions of
the tablet resemble those of a hard gelatin capsule. For example,
where the dosage form is fabricated to dimensions comparable to a
size 0 capsule, dimension D1 illustrated in FIG. 3 represents a
value of approximately 8 mm. The thickness of the drug layer can be
selected such that it represents a range of 0.05D1 to 0.95D1. The
drug layer most commonly represents a thickness in the range of
0.2D1 to 0.8D1, with a thickness of 0.5D1 to 0.7D1 being especially
preferred. The drug layer may itself be divided into a number of
layers (for example, two to four sublayers) and fabricated using
conventional multilayer tableting presses. The individual sublayers
may be varied in number and thickness, generally within the overall
dimensional ranges set forth above, and each sublayer may have
varying drug concentrations of the same or different drugs to alter
the delivery profile(s) of the drug(s). One or more of the
sublayers may be inert if a pulsed delivery of drug is desirable;
or, the first, outer sublayer of the drug layer may have a low
concentration of drug relative to the next sublayer, and so on, to
provide an ascending profile of drug delivery and each sublayer
having a higher concentration of drug than its predecessor is
exposed to the environment of use. Other designs of the dosage form
to effect particular delivery profiles or periods of drug delivery
will be apparent to one skilled in the art.
[0080] It is preferred that the dosage forms of this invention be
administered when the subject is in the fed state to allow time for
maximum swelling of the polymer matrix prior to the housekeeping
wave being initiated. Generally a meal size that results in a delay
of the housekeeping wave of from about 1 to 3 hours is
satisfactory. It may be preferable to administer one or more of the
dosage forms at the start of each dosing period, depending on the
size of the dosage form, to facilitate swallowing and yet provide
sufficient dose of active agent. Particularly in those instances
where the dosage form is near the lower end of the size range,
i.e., the maximum diameter along the longitudinal axis is on the
order of 7-13 mm, it is preferable that the dosage form be
administered to the subject in the fed state to allow for
significant swelling of the dosage form prior to the housekeeping
wave occurring. Typically, administration will occur with the meal
or within two hours thereafter, and preferably within one hour of
completion of the meal. Depending on the half-life of an active
agent, once-a-day dosing could conveniently occur with or after
dinner. For b.i.d. (i.e., twice-a-day) dosing to a human subject,
the dosage form can conveniently be administered with or after
breakfast and dinner, but, if after, preferably within one or two
hours after conclusion of the meal. For more frequent
administration, such as t.i.d., the dosage form may be administered
after breakfast, lunch and dinner. For administration within usual
meal patterns, it is desirable that the subject consume small
amounts of food or liquids prior to administration of the dosage
form. The dosage form may be administered prior to the taking of
food if administered with a sufficient quantity of liquid so as to
delay onset of the housekeeping wave, until consumption of food is
initiated.
[0081] To facilitate retention of the dosage forms of the
invention, particularly if the dosage form is to be administered to
a subject in the fasted state, it may be desirable to combine one
or more gastric-emptying delaying agents with the active agent
composition or coat the dosage form with a composition containing a
gastric-emptying delaying agent, i.e., a substance that delays
onset of the housekeeping wave of the IMMC. Examples of agents for
delaying onset of the housekeeping wave, preferably locally
delivered by the dosage form in amounts not resulting in any
substantial systemic effect to the subject, as for example,
anticholenergic agents such as propantheline, and other agents
including, but not limited to, methylcellulose, guar gum, fats such
as triglyceride esters, e.g., triethanol myristate, fatty acids of
10-15 carbon atoms, and the like.
[0082] FIGS. 5 and 6 show dosage form 10 after a length of time in
the fluid environment of the stomach. The polymer matrices have
eroded at the exposed surfaces of the matrices, i.e., those
portions of the matrices not covered by the insoluble material 18
to such an extent that the device 10 is smaller than its initial
swollen configuration. Erosion of the matrices will continue to
deliver active agent to the stomach until the dosage form has
substantially eroded so that no significant amount of active agent
remains or has eroded to such an extent that the remainder of the
dosage form is expelled from the stomach. Band 18 will be expelled
from the stomach either alone if it has separated from the dosage
form at some time near the end of the delivery period or as part of
the remainder of the dosage form expelled from the stomach. In some
applications, it may be desirable to form band 18 with weakened
portions so that band 18 splits and falls away from the polymer
matrices after some predetermined time in the stomach to permit a
particular release pattern of active agent from the dosage form
over the delivery period.
[0083] The polymer matrices forming layers 12 and 14 and useful in
this invention can be prepared by standard methods from the
materials previously described. The following description will be
directed to the active agent layer 14; however, the same procedures
may be applied for layer 12 by eliminating the active agent.
[0084] Typically, for example, an appropriate quantity of an active
agent or agents and the polymer ingredients are separately passed
through a screen, such as a screen having a mesh of about 40 wires
per inch, to reduce any larger sized materials, and dry mixed.
Then, a pharmaceutically-acceptable liquid, having a sufficient
vapor pressure to allow subsequent drying over a reasonable period
of time, for example 24 hours, is added to the dry mixture and the
damp mass is extruded through a mesh screen (e.g. 20 wires per
inch) to further mix the materials. Examples of suitable liquids
are water, methanol, ethanol, isopropanol, acetone, ethyl acetate,
and the like. After the extrusion process, the mixture is allowed
to dry, for example in air overnight at room temperature if the
active agent does not require any special handling. After drying,
the resulting material is granulated, for example by passing the
dried material through a mesh screen (e.g., 20 wires per inch). The
granules are combined with a suitable tableting lubricant which has
been previously passed through a mesh screen (e.g., 60 wires per
inch). The resulting material is tumbled to produce the finished
granulation for the tableting process. Tablets are produced using
well known methodologies associated with horizontal and vertical
compression units using dies and punches of appropriate dimensions.
Alternate granulation methods, for example, fluid bed granulation
or direct compression granulation can be used as well and such
method will be chosen by one skilled in the art depending on the
particular nature of the materials being used and the convenience
and preference of the fabricator. To form the laminated structure
of the dosage form, either the granulated first layer 12 or the
second layer 14 is first compressed in an appropriately sized
tableting mold, and then the other granulated layer is added to the
same mold over the compressed layer and compressed to form the
bilayer laminated core.
[0085] While the foregoing process has been described with respect
to dry ingredients, including the active agent, methodologies for
active agents in other than the solid state can be employed. For
example, if the active agent is not crystalline, but is in liquid
form, the active agent may first be encapsulated as microcapsules
to provide a solid that can be fabricated a described above.
Microencapsulation of the liquid active agent can be accomplished
by standard encapsulation techniques including, for example, spray
coating, spray drying encapsulation, centrifugal suspension, and
phase inversion techniques as described in Polymeric Delivery
Systems--Properties and Applications, ACS Symposium Series 520,
edited by El-Nokaly, Piatt and Charpentier (1993), which is
incorporated herein by reference. Additionally, liquid active
agents can be absorbed into porous clays and polymers and then
further incorporated into the polymer matrix of the dosage
form.
[0086] In certain applications where it is desirable to dispense an
active agent as a liquid or in a liquid state, it has been found
convenient to sorb the liquid, active agent formulation into porous
particles which are then formulated into the polymer matrix.
Materials useful for sorbing the liquid, active agent formulations
are porous particulates that are characterized by high
compressibility or tensile strength to withstand compacting forces
applied during compacting steps and minimize exudation of liquid,
active agent formulation from the pores; low friability so as to
preclude or minimize exudation of the liquid, active agent
formulation from the particles during compacting steps; and high
porosity so as to absorb an adequate of amount of a liquid, active
agent formulation to provide an effective amount of active agent in
a dosage form. The particles should be adapted to absorb an amount
of liquid, active agent formulation such that a therapeutically
effective amount of the active agent may be delivered in a unitary
dosage form that is of a size that can be conveniently swallowed by
a subject and, preferably provided in four or fewer tablets or
capsules for ingestion at the same time. The porosity of the
particles should be such that at least 5% by weight of the liquid,
active agent formulation, based on the total weight of the particle
may be sorbed into the pores of the particles, while the particles
exhibit sufficient strength at such degree of active agent loading
so as not to significantly be crushed or pulverized by compacting
forces to which the particles may be subjected during manufacturing
operations. Up to 50% by weight of the liquid, active agent
formulation may be sorbed into crystalline porous particles, such
as calcium hydrogen phosphate, but more typically 30-40%. Greater
amounts of liquid, active agent formulation may be sorbed into the
amorphous particles, such as the magnesium
aluminometasilicates.
[0087] Preferred materials are those having a strength to resist
compression forces of greater than 1500 kg/cm.sup.2 without
substantial exudation of the liquid, active agent formulation, and
most preferably without the tablet hardness plateauing.
[0088] A particularly suitable porous particle is exemplified by
the particular form of calcium hydrogen phosphate described in U.S.
Pat. No. 5,486,365, which is incorporated herein by reference. As
described therein, calcium hydrogen phosphate is prepared by a
process yielding a scale-like calcium hydrogen phosphate that can
be represented by the formula CaHPO.sub.4.mH.sub.2O wherein m
satisfies the expression 0.ltoreq.m.ltoreq.2.0. The scale-like
calcium hydrogen phosphate produced has characteristic physical
properties that make it particularly suitable for use in the
present invention. The scale-like material provides high specific
surface area, high specific volume, high capacity for water and oil
absorption, and the ability to readily form into spheres upon spray
drying. The spherical particulates have excellent flow properties
and permit compaction in the carrier matrix without significant
crushing or pulverizing of the particles during the compaction
step.
[0089] The scale-like calcium hydrogen phosphate particles
generally have a BET specific surface area of at least 20
m.sup.2/g, typically 20 m.sup.2/g-60 m.sup.2/g, a specific volume
of at least 1.5 ml/g, typically 2-5 ml/g or more, and an oil and
water absorption capacity of at least 0.7 ml/g, typically 0.8-1.5
ml/g. When formed into spheres the spherical particulates may have
a mean particle size of at least 70 microns, usually about 70-130
microns, and often about 90-120 microns. The particle size
distribution may be 100% through 40 mesh, 50%-100% through 100
mesh, and 20%-60% through 200 mesh. The bulk density may be from
about 0.4 g/ml-0.6 g/ml.
[0090] A most preferred form of calcium hydrogen phosphate is that
sold under the trademark FujiCalin.RTM. by Fuji Chemical Industries
(U.S.A.) Inc., Englewood, N.J., in types SG and S. Typical
parameters for that material include a mean pore size on the order
of 70 Angstroms, a mean particle size of about 110 microns, a
specific volume of about 2 ml/g, a BET specific surface area of
about 30-40 m.sup.2/g, and an oil and water absorption capacity of
about 0.8 ml/g. Type SG typically will have a particle size
distribution of 100% through 40 mesh, 60% through 100 mesh and 20%
through 200 mesh. Type S typically will have a particle size
distribution of 100% through 40 mesh, 90% through 100 mesh and 60%
through 200 mesh. Mixtures of the two types may be conveniently
employed to provide particulates having physical characteristics
that are suitable for various applications, as may be determined by
those skilled in the art of pharmaceutical formulation, tableting
and manufacturing.
[0091] The calcium hydrogen phosphate has low friability,
demonstrating a tensile strength of up to about 130 Kg/cm.sup.2
when subjected to compressive forces of up to 3000 Kg/cm.sup.2. The
angle of repose for the preferred materials typically is on the
order of 32-35 degrees.
[0092] Another material that may be utilized is that formed of
magnesium aluminometasilicate which may be represented by the
general formula
Al.sub.2O.sub.3MgO.2SiO.sub.2.nH.sub.2O
[0093] wherein n satisfies the relationship 0.ltoreq.n.ltoreq.10.
Commercially available magnesium aluminometasilicates are sold as
Grades S.sub.1, SG.sub.2, UFL.sub.2, US.sub.2, FH.sub.1, FH.sub.2,
FL.sub.1, FL.sub.2, S.sub.2, SG.sub.2, NFL.sub.2N, and NS.sub.2N,
under the trademark Neusilin.TM. by Fuji Chemical Industries
(U.S.A.) Inc., Englewood, N.J. Especially preferred grades are
S.sub.1, SG.sub.1, US.sub.2 and UFL.sub.2. Those materials are
amorphous and typically have a specific surface area (arca) of
about 100-300 m.sup.2/g, an oil absorption capacity of about
1.3-3.4 ml/g, a mean particle size of about 1-2 microns, an angle
of repose about 25.degree.-45.degree., a specific gravity of about
2 g/ml and a specific volume of about 2.1-12 ml/g.
[0094] Other absorptive materials may be substituted for the
foregoing. For example, powders of microcrystalline cellulose sold
under the tradenames Avicel (FMC Corporation) and Elcema (Degussa),
porous sodium carboxy methylcellulose cross-linked sold as
Ac-Di-Sol (FMC Corporation), porous soy bean hull fiber sold under
the trade name FI-1 Soy Fiber (Fibred Group), and porous
agglomerated silicon dioxide, sold under the tradenames Cab-O-Sil
(Cabot) and Aerosil (Degussa), may be used.
[0095] The liquid, active agent formulation may be in any form that
can be dispensed from the inside of the pores as the drug layer
disintegrates in the environment of use. The formulation, for
example, may be neat, liquid active agent, liquid active agent in a
solution, suspension, emulsion or self-emulsifying composition, or
the like, or a lipsomal solution or solid formulation, or solid
active agent in solution, suspension or slurry. Optionally other
dosage-forming ingredients, such as an anti-oxidant, a suspending
agent, a surface active agent, and the like may be present in the
liquid, active agent formulation. The liquid, active agent
formulation will be released in a form most suitable to provide
active agent to the site of delivery in a state in which it may be
rapidly absorbed in the environment of use to provide its
beneficial action with minimum delay once delivered to the
absorption site.
[0096] The present invention may have particular utility in the
delivery of liquid, active agent formulations that are in the form
of emulsions or self-emulsifying compositions. The term emulsion as
used in this specification denotes a two-phase system in which one
phase is finely dispersed in the other phase. The term emulsifier,
as used by this invention, denotes an agent that can reduce and/or
eliminate the surface and the interfacial tension in a two-phase
system. The emulsifier agent, as used herein, denotes an agent
possessing both hydrophilic and lipophilic groups in the emulsifier
agent. The term microemulsion, as used herein, denotes a
multicomponent system that exhibits a homogenous single phase in
which quantities of a drug can be solubilized. Typically, a
microemulsion can be recognized and distinguished from ordinary
emulsions in that the microemulsion is more stable and usually
substantially transparent. The term solution, as used herein,
indicates a chemically and physically homogenous mixture of two or
more substances.
[0097] The emulsion formulations of active agent generally comprise
0.5 wt % to 99 wt % of a surfactant. The surfactant functions to
prevent aggregation, reduce interfacial tension between
constituents, enhance the free-flow of constituents, and lessen the
incidence of constituent retention in the dosage form. The
therapeutic emulsion formulations useful in this invention may
comprise a surfactant that imparts emulsification comprising a
member selected from the group consisting of polyoxyethylenated
castor oil comprising 9 moles of ethylene oxide, polyoxyethylenated
castor oil comprising 15 moles of ethylene oxide, polyoxyethylene
castor oil comprising 20 moles of ethylene oxide,
polyoxyethylenated castor oil comprising 25 moles of ethylene
oxide, polyoxyethylenated castor oil comprising 40 moles of
ethylene oxide, polyoxylenated castor oil comprising 52 moles of
ethylene oxide, polyoxyethylenated sorbitan monopalmitate
comprising 20 moles of ethylene oxide, polyoxyethylenated sorbitan
monolaurate comprising 20 moles of ethylene oxide,
polyoxyethylenated sorbitan monolaurate comprising 20 moles of
ethylene oxide,polyoxyethylenated sorbitan monooleate comprising 20
moles of ethylene oxide, polyoxyethylenated sorbitan monostearate
comprising 4 moles of ethylene oxide, polyoxyethylenated sorbitan
tristearate comprising 20 moles of ethylene oxide,
polyoxyethylenated sorbitan monostearate comprising 20 moles of
ethylene oxide, polyoxyethylenated sorbitan trioleate comprising 20
moles of ethylene oxide, polyoxyethylenated stearic acid comprising
8 moles of ethylene oxide, polyoxyethylene lauryl ether,
polyoxyethylenated stearic acid comprising 40 moles of ethylene
oxide, polyoxyethylenated stearic acid comprising 50 moles of
ethylene oxide, polyoxyethylenated stearyl alcohol comprising 2
moles of ethylene oxide, and polyoxyethylenated oleyl alcohol
comprising 2 moles of ethylene oxide. The surfactants are available
from Atlas Chemical Industries, Wilmington, Del.; Drew Chemical
Corp., Boonton, N.J.; and GAF Corp., New York, N.Y.
[0098] Typically, an active agent emulsified formulation useful in
the invention initially comprises an oil phase. The oil phase of
the emulsion comprises any pharmaceutically acceptable oil which is
not miscible with water. The oil can be an edible liquid such as a
non-polar ester of an unsaturated fatty acid, derivatives of such
esters, or mixtures of such esters can be utilized for this
purpose. The oil can be vegetable, mineral, animal or marine in
origin. Examples of non-toxic oils comprise a member selected from
the group consisting of peanut oil, cottonseed oil, sesame oil,
olive oil, corn oil, almond oil, mineral oil, castor oil, coconut
oil, palm oil, cocoa butter, safflower, a mixture of mono- and di-
glycerides of 16 to 18 carbon atoms, unsaturated fatty acids,
fractionated triglycerides derived from coconut oil, fractionated
liquid triglycerides derived from short chain 10 to 15 carbon atoms
fatty acids, acetylated monoglycerides, acetylated diglycerides,
acetylated triglycerides, olein known also as glyceral trioleate,
palmitin known as glyceryl tripalmitate, stearin known also as
glyceryl tristearate, lauric acid hexylester, oleic acid
oleylester, glycolyzed ethoxylated glycerides of natural oils,
branched fatty acids with 13 molecules of ethyleneoxide, esters of
saturated coconut and palm kernal fatty acids, caprylic and capric
acid wlth glycerol or propylene glycol such as Miglyols supplied by
Hulls America, Somerset, N.J., and oleic acid decylester. The
concentration of oil, or oil derivative in the emulsion formulation
is 1 wt % to 40 wt %, with the wt % of all constituents in the
emulsion preparation equal to 100 wt %. The oils are disclosed in
Pharmaceutical Sciences by Remington, 17.sup.th Ed., pp. 403-405,
(1985) published by Mark Publishing Co., in Encyclopedia of
Chemistry, by Van Nostrand Reinhold, 4.sup.th Ed., pp. 644-645,
(1986) published by Van Nostrand Reinhold Co.; and in U.S. Pat. No.
4,259,323 issued to Ranucci.
[0099] Dosage forms of this invention may be utilized to delivery
liquid formulations such as contained in immediate-release,
commercially-available dosage forms over a prolonged period of
time. Examples of commercially available encapsulated liquid
formulations that may be utilized include, inter alia,
Placidyl.RTM. brand of ethchlorvynol, Adalat.RTM. brand of
nifedipine, VePesid.RTM. brand of etoposide, Lanoxicaps.RTM. brand
of digoxin, Zantace.RTM. brand of ranitidine hydrochloride,
Sandimmune.RTM. and Neoral.RTM. brands of cyclosporin,
Calderol.RTM. brand of calcifediol, Zarontin.RTM. brand of
ethosuximide, Procardia.RTM. brand of nifedipine, Rocaltrol.RTM.
brand of calcitriol and Vescenoide.RTM. brand of tretinoin.
[0100] The dosage form may contain an antioxidant to slow or
effectively stop the rate of any autoxidizable material present in
the dosage form. Representative antioxidants comprise a member
selected from the group of ascorbic acid; alpha tocopherol;
ascorbyl palmitate; ascorbates; isoascorbates; butylated
hydroxyanisole; butylated hydroxytoluene; nordihydroguiaretic acid;
esters of garlic acid comprising at least 3 carbon atoms comprising
a member selected from the group consisting of propyl gallate,
octyl gallate, decyl gallate, decyl gallate;
6-ethoxy-2,2,4-trimethyl-1,2-dihydro-guinoline;
N-acetyl-2,6-di-t-butyl-p- -aminophenol; butyl tyrosine;
3-tertiarybutyl-4-hydroxyanisole;
2-tertiary-butyl-4-hydroxyanisole; 4-chloro-2,6-ditertiary butyl
phenol; 2,6-ditertiary butyl p-methoxy phenol; 2,6-ditertiary
butyl-p-cresol: polymeric antioxidants; trihydroxybutyro-phenone
physiologically acceptable salts of ascorbic acid, erythorbic acid,
and ascorbyl acetate; calcium ascorbate; sodium ascorbate; sodium
bisulfite; and the like. The amount of antioxidant used for the
present purposes is about 0.001% to 25% of the total weight of the
composition present in the dosage form. Antioxidants are known to
the prior art in U.S. Pat. Nos. 2,707,154; 3,573,936; 3,637,772;
4,038,434; 4,186,465 and 4,559,237.
[0101] The dosage form may also contain a chelating agent to
protect the active agent either during storage or when in use.
Examples of chelating agents include, for example, polyacrylic
acid, citric acid, edetic acid, disodium edetic acid, and the like.
The chelating agent may be co-delivered with the active agent in
the environment of use to preserve and protect the active agent in
situ. Protection is provided for active agents which are
inactivated by chelation with multivalent metal cations such as
calcium, magnesium or aluminum that may be present in some foods
and are at natural background levels in the fluids of the
gastrointestinal tract. Such chelating agents may be combined with
the liquid, active agent formulation in the porous particles, or
the chelating agents may be incorporated into the matrix in which
the porous particles are dispersed.
[0102] The liquid formulation may also comprise a surfactant or a
mixture of surfactants where the surfactant is selected from the
group consisting of nonionic, anionic and cationic surfactants.
Exemplary nontoxic, nonionic surfactants suitable for forming a
composition comprise alkylated aryl polyether alcohols known as
Triton.RTM.; polyethylene glycol tertdodecyl throether available as
Nonic.RTM.; fatty and amide condensate or Alrosol.RTM.; aromatic
polyglycol ether condensate or Neutronyx.RTM.; fatty acid
alkanolamine or Ninol.RTM. sorbitan monolaurate or Span.RTM.;
polyoxyethylene sorbitan esters or Tweens.RTM.; sorbitan
monolaurate polyoxyethylene or Tween 20.RTM.; sorbitan mono-oleate
polyoxyethylene or Tween 80.RTM.; triblock copolymers
polyoxyethylene-polyoxypropylene-polyoxyethylene also known as
Pluronics.RTM.; polyglycolyzed glycerides such as Labrasol, PEG-8
glyceryl caprylate/caprate, PEG-4 glyceryl caprylate/caprate,
polyglyceryl-3 isostearate, PEG-6 glyceryl monooleate, PEG-6
glyceryl linoleate, PEG-32 palmito stearate, PEG-32 glyceryl
stearate, saccharose distearate, saccharose mono-di stearate,
saccharose monoplamitate, glyceryl monolaurate, Imwitors, Softisans
and Dynasans as supplied by Hulls America, Somerset, N.J.,
polyoxyethylated castor oil such as Cremophor and
polyoxypropylene-polyoxyethylene. By way of example, anionic
surfactants comprise sulfonic acids and the salts of sulfonated
esters such as sodium lauryl sulfate, sodium sulfoethyl oleate,
dioctyl sodium sulfosuccinate, cetyl sulfate sodium, myristyl
sulfate sodium; sulated esters; sulfated amides; sulfated alcohols;
sulfated ethers; sulfated carboxylic acids; sulfonated aromatic
hydrocarbons; sulfonated ethers; and the like. The cationic surface
active agents comprise cetyl pyridinium chloride; cetyl trimethyl
ammonium bromide; diethylmethyl cetyl ammonium chloride;
benzalkonium chloride; benzethonium chloride; primary alkylamonium
salts; secondary alkylamonium salts; tertiary alkylamonium salts;
quaternary alkylamonium salts; acylated polyamines; salts of
heterocyclic amines; palmitoyl carnitine chloride, behentriamonium
methosulfate, and the like. Generally, from 0.01 part to 1000 parts
by weight of surfactant, per 100 parts of active agent is admixed
with the active agent to provide the active agent formulation.
Surfactants are known to the prior art in U.S. Pat. Nos. 2,805,977;
and in 4,182,330.
[0103] The liquid formulation may comprise permeation enhancers
that facilitate absorption of the active agent in the environment
of use. Such enhancers may, for example, open the so-called "tight
junctions" in the gastrointestinal tract or modify the effect of
cellular components, such a p-glycoprotein and the like. Suitable
enhancers include alkali metal salts of salicyclic acid, such as
sodium salicylate, caprylic or capric acid, such as sodium
caprylate or sodium caprate, diethylene glycol monoethyl ether,
propylene glycol laurate, and the like. Enhancers may include the
bile salts, such as sodium deoxycholate. Various p-glycoprotein
modulators are described in U.S. Pat. Nos. 5,112,817 and 5,643,909,
which are incorporated herein by reference. Various other
absorption enhancing compounds and materials are described in U.S.
Pat. No. 5,824,638, which also is incorporated herein by reference.
Enhancers may be used either alone or as mixtures in combination
with other enhancers.
[0104] The liquid, active agent formulation of the dosage form may
optionally be formulated with inorganic or organic acids or salts
of drugs which promote dissolution and disintegration or swelling
of the porous particles upon contact with biological fluids. The
acids serve to lower the pH of the microenvironment at the porous
particle, and promote rapid dissolution of a particle, such as
calcium hydrogen phosphate, that is soluble in low pH environments,
thus providing rapid liberation of the liquid, active agent
formulation contained in the porous particle. Examples of organic
acids include citric acid, tartaric acid, succinic acid, malic
acid, fumaric acid and the like. Salts of drugs where the anion of
the salt is acidic, such as acetate, hydrochloride, hydrobromide,
sulfate, succinate, citrate, and the like, can be utilized to
produce immediate disintegration and dissolution of the porous
particle. A more complete list of acidic components for this
application is provided in Journal of Pharmaceutical Sciences,
"Pharmaceutical Salts", Review Articles, January, (1977), Vol. 66,
No. 1, pages 1-19. The interaction of an acidic component with a
porous particle of, for example, calcium hydrogen phosphate, in the
presence of water from gastric fluids accelerates dissolution of
the particle at a greater rate than gastric fluid alone, producing
a more rapid and complete release of the liquid, active agent
formulation into the environment of use. Likewise alkaline
components or salts of drugs where the cation of the salt is
alkaline such as choline may be incorporated into the liquid,
active agent formulation to promote rapid and complete dissolution
of a porous particle which is soluble or swells at elevated pH.
Such a particle may be formed, for example, of poly(methacrylic
acid-methyl methacrylate) 1:2 available commercially as Eudragit
S100 (Rohm America, Sommerset, N.J.
[0105] In order to prepare a dosage form of the present invention,
the first layer 12 typically is prepared by granulation and
tableting methods described previously and which are conventionally
described in Remington's Pharmaceutical Sciences, Eighteenth
Edition (1990). Then, the active agent layer 14 is prepared and
laminated onto layer 12, to provide a dosage form of the desired
size and shape. In its initial prepared form, the dosage form is
about the size and dimensions of a size "000" to size 5 hard
gelatin capsule. The cross-sectional shape of the matrix may be
circular or may be oval, triangular, square, hexagonal or other
shapes that are easily handled, especially by patients with limited
dexterity. Presently preferred shapes are those in which the
cross-section is circular or oval. The bands are then placed onto
the surface of active agent formulation matrix or printed onto the
surface using conventional banding or printing techniques, such as
disclosed herein or in U.S. Pat. No. 5,534,263, which is
incorporated herein by reference.
[0106] As described above, the active agent itself may be in
liquid, solid or semisolid form. The active agent formulation may
contain additional materials and may be designed in a multitude of
ways to provide a specific active agent delivery profile. In one
embodiment the active agent is capable of slow dispersion or
dissolution in the stomach. In another embodiment, the polymer
matrix of layer 14 may contain a surfactant so that the formulation
is more readily susceptible to erosion in the stomach. In still
another embodiment, the formulation of layer 14 may include a solid
surfactant and provide active agent delivery in a finely dispersed
form. In yet another embodiment, formulation layer 14 may include a
lipidic or wax matrix that erodes as the active agent is released.
In yet a further embodiment, the formulation may include coated
microspheres of an active agent or microspheres of an active agent
and an adjuvant. The active agent either alone or with adjuvant can
be delivered simultaneously from the microspheres either by
diffusion or by osmosis. Suitable materials useful as active agent
carriers and excipients are known in the art and are disclosed in
U.S. Pat. Nos. 4,595,583 and 4,874,388, for example. For active
agents that may tend to degrade in the stomach, the active agent
can be enterically coated to protect the active agent it passes to
the small intestine in accordance with conventional coating
methods.
[0107] The dispensing devices of the invention find use, for
example, in humans or other animals. The environment of use is a
fluid environment and for the purposes of this invention primarily
includes the fluid environment of the stomach and the upper
intestinal tract or small intestine. A single dispensing device or
several dispensing devices can be administered to a subject during
a therapeutic program.
[0108] The terms "active agent" and "drug" are used interchangeably
herein and refer to an agent, active agent, compound, composition
of matter or mixture thereof which provides some pharmacologic,
often beneficial, effect. This includes foods, food supplements,
nutrients, drugs, antiacids, vitamins such as, for example, Vitamin
C, Vitamin E, microorganism attenuators and other agents that
benefit the environment of use. As used herein, the terms include
any physiologically or pharmacologically active substance that
produces a localized or systemic effect or effects in animals,
including warm blooded mammals, humans and primates; domestic
household or farm animals such as cats, dogs, sheep, goats, cattle,
horses and pigs; laboratory animals such as mice, rats and guinea
pigs; zoo and wild animals; and the like. The active agent that can
be delivered includes inorganic and organic compounds, including,
without limitation, active agents which act on the peripheral
nerves, adrenergic receptors, cholinergic receptors, the skeletal
muscles, the cardiovascular system, smooth muscles, the blood
circulatory system, synoptic sites, neuroeffector junctional sites,
endocrine and hormone systems, the immunological system, the
reproductive system, the skeletal system, autacoid systems, the
alimentary and excretory systems, the histamine system and the
central nervous system.
[0109] Suitable active agents may be selected from, for example,
proteins, enzymes, enzyme inhibitors, hormones, polynucleotides,
nucleoproteins, polysaccharides, glycoproteins, lipoproteins,
peptides, polypeptides, steroids, hypnotics and sedatives, psychic
energizers, tranquilizers, anticonvulsants, antidepressants, muscle
relaxants, antiparkinson agents, analgesics, immunosuppressants,
anti-inflammatories, antihistamines, local anesthetics, muscle
contractants, antimicrobials, antimalarials, antivirals,
antibiotics, antiobesity agents, antidiabetic agents, hormonal
agents including contraceptives, sympathomimetics, polypeptides and
proteins capable of eliciting physiological effects, diuretics,
lipid regulating agents, antiandrogenic agents, antiparasitics,
neoplastics, antineoplastics, antihyperglycemics, hypoglycemics,
nutritional agents and supplements, growth supplements, fats,
ophthalmics, antienteritis agents, electrolytes and diagnostic
agents.
[0110] Examples of active agents useful in this invention include
prochlorperazine edisylate, ferrous sulfate, albuterol,
aminocaproic acid, mecamylamine hydrochloride, procainamide
hydrochloride, amphetamine sulfate, methamphetamine hydrochloride,
benzphetamine hydrochloride, isoproterenol sulfate, phenmetrazine
hydrochloride, bethanechol chloride, methacholine chloride,
pilocarpine hydrochloride, atropine sulfate, scopolamine bromide,
isopropamide iodide, tridihexethyl chloride, phenformin
hydrochloride, metformin, methylphenidate hydrochloride,
acrivastine, benazepril, carbamazipine, chlorothiazide,
desmopressin, dicumarol, furosemide, gepirone griseofulvin,
levodopa/benserazide, llithium, methylphenidate, 8-methoxalen,
metoprolol, misoprostol, octreotide, phenobarbital, phenytoin,
piretanide, paraastatin, propoxyphen, riboflavin, sertaline,
spironolactone, sumatriptan, ticlopidine, theophylline cholinate,
cephalexin hydrochloride, diphenidol, meclizine hydrochloride,
prochlorperazine maleate, phenoxybenzamine, thiethylperazine
maleate, anisindione, diphenadione erythrityl tetranitrate,
digoxin, isoflurophate, acetazolamide, nifedipine, methazolamide,
bendroflumethiazide, chlorpropamide, glipizide, glyburide,
gliclazide, tobutamide, chlorproamide, acetohexamide, troglitazone,
orlistat, bupropion, nefazodone, tolazamide, chlormadinone acetate,
phenaglycodol, allopurinol, aluminum aspirin, methotrexate, acetyl
sulfisoxazole, hydrocortisone, hydrocorticosterone acetate,
cortisone acetate, dexamethasone and its derivatives such as
betamethasone, triamcinolone, methyltestosterone,
17-.beta.-estradiol, ethinyl estradiol, ethinyl estradiol 3-methyl
ether, prednisolone, 17-.beta.-hydroxyprogesterone acetate,
19-nor-progesterone, norgestrel, norethindrone, norethisterone,
norethiederone, progesterone, norgesterone, norethynodrel,
terfandine, fexofenadine, aspirin, acetaminophen, indomethacin,
naproxen, fenoprofen, sulindac, indoprofen, nitroglycerin,
isosorbide dinitrate, propranolol, timolol, atenolol, alprenolol,
cimetidine, clonidine, imipramine, levodopa, carbidopa,
carbidopa/levodopa, selegiline, chlorpromazine, methyldopa,
dihydroxyphenylalanine, calcium gluconate, ketoprofen, ibuprofen,
colchicine, cephalexin, erythromycin, haloperidol, zomepirac,
ferrous lactate, vincamine, phenoxybenzamine, diltiazem, milrinone,
captropril, mandol, quanbenz, hydrochlorothiazide, ranitidine,
flurbiprofen, fenbufen, fluprofen, tolmetin, alclofenac, mefenamic,
flufenamic, difuninal, nimodipine, nitrendipine, nisoldipine,
nicardipine, felodipine, lidoflazine, tiapamil, gallopamil,
amlodipine, mioflazine, lisinopril, enalapril, captopril, ramipril,
enalaprilat, famotidine, nizatidine, sucralfate, etintidine,
tetratolol, minoxidil, chlordiazepoxide, diazepam, amitriptyline,
and imipramine, and pharmaceutical salts of these active agents.
Further examples are proteins and peptides which include, but are
not limited to, cyclosporins such as cyclosporine A, insulin,
glucagon, thyroid stimulating hormone, parathyroid and pituitary
hormones, calcitonin, renin, prolactin, corticotrophin, thyrotropic
hormone, follicle stimulating hormone, chorionic gonadotropin,
gonadotropin releasing hormone, bovine somatotropin, porcine
somatropin, oxytocin, vasopressin, prolactin, somatostatin,
lypressin, pancreozymin, luteinizing hormone, LHRH, interferons,
interleukins, growth hormones such as human growth hormone, bovine
growth hormone and porcine growth hormone, fertility inhibitors
such as the prostaglandins, fertility promoters, growth factors,
and human pancreas hormone releasing factor.
[0111] The present invention is particularly useful to deliver
active agents that are poorly absorbed in the lower
gastrointestinal tract, but well absorbed in the upper
gastrointestinal tract (i.e., the small intestine) or active agents
that exhibit poor solubility such that the increased retention time
in the stomach allows for a greater quantity of active agent to
dissolve from the dosage form than would otherwise be dissolved.
Typically, antiviral, antifungal and antibiotic agents, e.g.
sulfonamides, quinolones, penicillins, cephalosporins,
aminoglycosides, and tetracyclines, are representative classes of
agents for which the invention is particularly useful. Such
antibiotic agents may include, for example, .beta.-lactam
antibiotics, vancomycin, clidamycin, erthromycin, clarithromycin,
14-hydroxy clarithromycin, azithromycin, roxithromycin,
dirithromycin, trimethoprim-sulfamethoxaazole, rifampin,
ciprofloxacin, amoxicillin, clindamycin, ceftriaxone, cefotaxime,
chloramphenicol, clindamycin, cefoxitin, doxyclycline,
spectinomycin, ofloxacin, rifampin, minocycline, doxycycline,
aztreonam, imipenem, meropenem, nitrofurantoin, azithromycin,
atovaquone, trimetrexate, dapsone, primaquin, trimetrexate,
ketoconazole, floconazole, amphotericin B, itraconazole,
trifluridine, foscarnet, zidovudine amantadine, interferon alfa,
sulfonamides such as sulfisoxazole, sulfadiazine, and
sulfasalazine, quinolones and fluoroquinolones such as, for
example, cinoxacin, forfloxacin, diprofloxacin, ofloxacin,
spardlosxacin, lomefloxacin, fleroxacin, pefloxacin and
amifloxacin, gentamicin, tobramycin, amikacin,netihnicin,
kanamycin,and neomycin. Representative antiviral agents include
acyclovir, famciclovir, foscarnet, ganciclovir, ritonavir,
idoxuridine, sorivudine, trifluridine, valacylcovir, vidarabine,
didanosine, stavudine, zalcitabine, zidovudine, amantadine,
interferons, e.g., interfon alpha, ribavirin, rimantadine,
nucleoside RT inhibitors, such as lamivudine and adeforvir,
non-nucleoside inhibitors such as nevrapine, delavairidine,
lviride, saquinavir and indinavir, nucleoside DNAp inhibitors such
as famciclovir, fialuridine, cidofovir and lobucavir, antisense
oligonucleotides such as afovirsen, receptor decoys such as
sICAM-1, capsid binding agents such as pirodavir, and neuraminidase
inhibitors such as GG167.
[0112] Specific examples of active agents that are readily absorbed
in the upper gastrointestinal tract relative to the lower
gastrointestinal tract are acyclovir, ganciclovir, cimetidine,
ranitidine, captopril, methyldopa, selegiline and the like.
Specific examples of active agents that exhibit poor solubility in
water are diphenidol, meclizine hydrochloride, hydralazine,
prochloperazine maleate, phenoxybenzamine, triethylperazine
maleate, anisindone, diphenadione erythrityl tetranitrate, digoxin,
isofllurophate, acetazolamide, methazolamide, bendroflumethiazide,
chlorpropamide, tolazamide, chlormadionone acetate, phenaglycodol,
allopurinol, alluminum aspirin, methotrexate, acetyl sulfisoxazole,
erythromyciin, progestins, esterogenic, progestational
corticosteroids, hydrocortisone, hydrocorticosterone acetate,
cortisone acetate, tramcinolone, methyltesterone,
17-beta-estradiol, ethinyl estradiol, prazosin hydrochloride,
ethinyl estradiool 3-methyl ether, pednisolone,
17-alpha-hydroxyprogesterone acetate, 19-norprogesterone,
norgestrel, norethindrone, progesterone, norgesterone,
norethlynodrel, and the like.
[0113] Retention of the device of the present invention in the
stomach for a prolonged period of time make it especially useful
for the localized treatment of gastric acidity and gastrointestinal
disorders such as duodenal ulcers, peptic ulcers and chronic
gastritis, particularly those resulting from the presence of
Helicobacter pylori. Representative active agents for such uses
include cimetidine, rantitidine, famotidine, nizatidine, zolentine,
omeprazole, lansoprazole and active agents useful for the treatment
of Helicobacter pylori, such as metronidazole, timidazole,
amoxicillin, clarithromycin, minocycline and tetracycline.
[0114] While for reasons of efficacy, safety, economy, convenience
and/or efficiency it may be desirable to utilize a single active
agent in the active agent formulation, it is to be understood that
more than one active agent may be incorporated into the active
agent formulation in a device of this invention, and that the use
of the term "agent" or "active agent" in no way excludes the use of
two or more such agents or active agents. The agents can be in
various forms, such as uncharged molecules, components of molecular
complexes or nonirritating, pharmacologically acceptable salts.
Also, simple derivatives of the agents (such as prodrugs, ethers,
esters, amides, etc) which are easily hydrolyzed by body pH,
enzymes, etc, can be employed. Combinations of two or more active
agents can optionally be co-delivered, simultaneously or
sequentially from the dosage form of this invention. For
simultaneous delivery of two or more active agents, the active
agents will typically be uniformly dispersed throughout the dosage
form. For sequential delivery, different active agents can be
selectively placed within the dosage form during its manufacture,
as by using the multilaminate structure for layer 14 described
previously. Alternatively, a core that contains one active agent
can be prepared, and the core coated or formed with an outer layer
containing a second active agent. Initially, the agent in the outer
portion of the dosage form will be dispensed, and as the dosage
form erodes in the stomach, the second active agent will be
dispensed at a later time.
[0115] The active agent dosage form may include additional
ingredients, such as, for example, a buffer or other agents for
controlling pH in the stomach or elsewhere in the gastrointestinal
tract, an agent or agents for delaying onset of the housekeeping
wave, preferably locally delivered by the dosage form in amounts
not resulting in any substantial systemic effect to the subject, as
for example, anticholenergic agents such as propantheline, and
other agents including, but not limited to, methylcellulose, guar
gum, fats such as triglyceride esters, e.g., triethanol myristate,
fatty acids of 10-15 carbon atoms, and the like, a viscosity
regulating vehicle, a surfactant, a dye, a permeation enhancer, a
proteinase inhibitor, or other formulation ingredients and
additives, as are known in the art. The active agent dosage form
may also include minor amounts of polymers which serve useful
functions in tablet formation, for example, to improve the tablet
cohesiveness after compression or to improve the physical or
chemical stability of the dosage form. These polymers are added at
quantities less than 10% by weight and preferably less that 5% by
weight of the tablet. Examples of such polymers include
hydroxypropyl methyl cellulose having molecular weights of less
that 20,000 grams per mole, methycellulose having a molecular
weight of less than 20,000 grams per mole, polyvinyl pyrrolidone
having a molecular weight of less than 360,000 grams per mole, and
the like.
[0116] The amount of active agent employed in the delivery device
will be that amount necessary to deliver a therapeutically
effective amount of the agent to achieve the desired therapeutic
result, and may range from 1 ng to 2500 mg, although lower and
higher amounts may be used in particular circumstances. In
practice, this will vary widely depending upon the particular
agent, the degree of active agent absorption, the severity of the
condition, and the desired therapeutic effect. Thus, it is not
practical to define a particular range for the therapeutically
effective amount of each active agent incorporated into the device.
Such ranges can easily be determined by one skilled in the art
using conventional methods, for example from dose ranging and
plasma level studies. Any references to specific quantities of
active agent or specific dose ranges of active agent herein are
intended to include the amount or amounts of active agent specified
and bioequivalents thereof.
[0117] When the delivery device of this invention is being used to
substitute for one or more doses of an active agent presented in a
conventional dosage form that is usually prescribed for multiple
dosing during a predetermined period, the sum of the amounts of
active agent present in the multiple doses of the conventional
dosage form for use in the period may be used to determine an upper
limit on the of the amount of active agent to be included in the
device of this invention. For example, if the conventional dosage
form contains 200 mg of active agent and is to be administered
every 3 hours, a dosage form of this invention may be prepared for
administration every 6 hours, and that dosage form may contain 400
mg of active agent which will be delivered over the 6 hour
period.
[0118] However, when compliance with multiple dosing is a problem,
the advantage of administering the dosage forms of the invention at
fewer times throughout a twenty-four hour period may provide
incentive to incorporate greater amounts of active agent, where
such greater amounts do not have any deleterious effects. The
specific amount of active agent to be included in the dosage form
of the invention can easily be determined by routine dosage studies
that compare the blood plasma active agent levels of subjects with
conventional dosing and the dosage form of this invention.
[0119] The dosage forms of this invention can conveniently release
active agent in a controlled and sustained manner over a prolonged
period. Typically, active agent will be released from the dosage
form at a rate that releases a therapeutically effective amount of
active agent to the subject over a substantial portion of the
period between administration of the dosage forms. Typically,
release will occur over 40% of the period between repeated
administration of the dosage form, more preferably at least over
60% of the period, and most preferably over 80% of the period.
Dosage forms that result in a C.sub.max of the active agent in the
plasma of the subject being reached within 1-2 hours, and
maintained for a prolonged period, preferably, 4-6 hours, may be
particularly useful.
[0120] In an especially preferred embodiment, the invention
comprises a first layer 12 having a composition of 60-100 percent
of a water soluble, polyethylene oxide polymer having a molecular
weight between about 900,000 and 10,000,000, and a drug layer 14
having from about 10 weight percent to about 50 weight percent of a
water-soluble polyethylene oxide polymer having a molecular weight
between about 100,000 and 600,000 and from about 10 weight percent
to about 60 weight percent of a water-insoluble hydroxypropyl
cellulose polymer. The hydroxypropyl cellulose polymer preferably
has a hydroxypropyl content of between about 8-15 weight percent,
and most preferably between about 10-13 weight percent. The
composition of this invention is useful to prepare the active agent
dosage forms described herein, and finds particular utility with
respect to the antiviral, antimicrobial, antidiabetic,
antihyperglycemic, hypoglycemic, antidepressant, antiobesity, and
antifungal active agents described herein.
[0121] The following examples are illustrative of the present
invention. They are not to be construed as limiting the scope of
the invention. Variations and equivalents of these examples will be
apparent to those skilled in the art in light of the present
disclosure the drawings and the claims herein. In particular,
variations in the dosage forms described that are bioequivalent are
considered within the scope of the present invention.
Preparation 1
[0122] An example of a active agent which requires frequent dosing
is acyclovir. A typical dosing regimen for this antiviral active
agent is five doses per day administered every four hours. A dosage
form in accordance with this invention for twice daily dosing of
acyclovir is formulated according to the following procedures. The
dosage form is retained in the stomach and releases acyclovir over
a prolonged period of time.
[0123] 22.5 Grams of acyclovir and 3.6 grams of the gel-forming
polymer polyethylene oxide, having a number average molecular
weight of approximately 200,000 grams per mole, are separately
screened through a mesh having 40 wires per inch. The polyethylene
oxide is supplied under the trade name Polyox.RTM. grade WSR N80 as
manufactured by Union Carbide Corporation, Danbury, Conn. The sized
active agent and polymer are dry mixed. Then, 3.75 grams of a
hydroattractant water-insoluble polymer, hydroxypropyl cellulose
having a hydroxypropyl content of 10-13 weight percent and an
average fiber particle size of 50 microns, is sieved through the
40-mesh screen and blended into the mixture. The hydroxypropyl
cellulose is supplied as Low-Substituted Hydroxypropyl Cellulose
grade 11 as manufactured by Shin-Etsu Chemical Company, Ltd.,
Tokyo, Japan. Anhydrous ethyl alcohol, specially denatured formula
3A, i.e., ethanol denatured with 5 volume percent methanol, is
added to the mixture with stirring until a uniformly damp mass
formed. This damp mass is extruded with pressure through a screen
having 20 wires per inch. The extrudate is then allowed to air dry
at room temperature overnight. After drying, the resulting
extrudate is passed again through the 20-mesh sieve, forming
granules. 0.15 Grams of the tableting lubricant, magnesium
stearate, are passed through a sieve having 60 wires per inch. The
sized 60-mesh lubricant is then tumbled into the granules to
produce the finished drug layer granulation.
[0124] A separate granulation is prepared by passing 29.85 grams of
a different gel-forming polyethylene oxide through a mesh having 20
wires per inch. The polyethylene oxide has a molecular weight of
approximately 7 million and is supplied as Polyox grade WSR-303.
0.15 Grams of magnesium stearate sized through a 60 mesh screen is
tumbled into the 20 mesh Polyox 303, to produce the finished
retention-layer granulation.
[0125] 800 Milligram portions of the resulting drug layer
granulation and 250 mg portions of the retention-layer granulation
are weighed and compacted with caplet-shaped tooling on a Carver
press at pressure head of 1.5 tons to a target tablet weight, e.g.,
each approximately 1050 mg. The shape of the tablet has
approximately cylindrical proportions, for example, the diameter is
approximately 7.6 millimeters (mm) and the length approximately 22
mm. Such dosage form contains a unit dose of 600 mg acyclovir.
[0126] A tube of polyolefin material having an outside diameter of
7.7 mm and having a wall thickness of 0.25 mm is sliced with a
razor to produce rings. The width of each ring was approximately 3
mm. One ring is then press fitted onto each caplet such that the
ring, or band, is located approximately at the midpoint of the
length of the caplet. This step completes the fabrication procedure
of the acyclovir banded caplet. The acyclovir dosage forms prepared
as above are retained in the stomach and release acyclovir over a
prolonged period.
EXAMPLE 1 (ASSAY)
[0127] Banded devices fabricated in Preparation 1 are assayed for
dimensional changes and release of active agent as follows:
[0128] A banded dosage form is placed in a beaker of simulated
gastric fluid, as specified in U.S. Pharmacopedia/National
Formulary 23/18, having a pH of approximately 1.4 and a maintained
temperature of 37.degree. C. After one hour, the device is removed
and measured for dimensional change in length and diameter. The
swollen device will have the general appearance of the dosage form
shown in FIG. 4.
[0129] Samples of the dosage form are tested for release of active
agent by shaking at prescribed conditions in an aqueous media
simulating the media in the upper gastrointestinal tract. Each
dosage form is first placed in a cylindrical, slotted basket having
inside diameter of 15 mm and inside length of 52 mm. Each basket
has eight slots and each slot is 1-2 mm wide and 52 mm long and
positioned lengthwise along the length of the basket. The basket
containing the dosage form is then placed in 50 milliliters of
simulated gastric fluid and shaken at a frequency of 100 cycles per
minutes at an amplitude of 3.7 cm for one hour. Then, the baskets
containing the dosage forms are transferred to another set of
receptacles having the same fluid media composition and volume as
above and shaken for another hour. This procedure is continued
until the number of desired 50 ml release receptor samples
representing the number of hours of release are accumulated. After
the collective number of hours, each basket is transferred to a
fresh, single 50 ml receptor where it is then shaken for an
additional 3 hours. This completes the testing period. The
concentration of active agent in the resulting receptors is then
analyzed by using ultraviolet spectrometry assay at a wavelength
specific for the active agent being tested. The release of active
agent as a function of time, e.g. release rate (mg/hour),
cumulative release (mg), and time for 90% release of active agent
(T.sub.90) are determined.
EXAMPLE 2
[0130] Dosage forms of this invention containing the antiviral drug
ganciclovir are prepared in accordance with the procedures of
Preparation 1. The dosage forms prepared are retained in the
stomach and release ganciclovir over a prolonged period of
time.
EXAMPLE 3
[0131] Equivalent amounts of the following polymers are substituted
for the polyethylene oxide in the retention-layer in Preparation 1
(all molecular weights are number average molecular weights in
grams per mole): hydroxypropyl cellulose (MW: 1,000,000),
hydroxypropyl methyl cellulose (MW: 254,000), hydroxyethyl
cellulose (MW: 1,300,000), sodium carboxy methylcellulose (MW:
700,000), calcium carboxymethyl cellulose (MW: 700,000), methyl
cellulose (MW: 135,000), and polyvinyl alcohol (Elvanol.RTM. HV),
and dosage forms with a polyethylene band are fabricated to the
same dimensions as described in Preparation 1 with equivalent
quantities of the active agents acyclovir and ganciclovir. The
prepared dosage forms are retained in the stomach of a subject for
a prolonged period and deliver the antiviral active agents
ganciclovir and acyclovir over a prolonged period of time.
EXAMPLE 4
[0132] Dosage forms containing equivalent quantities of the
antiviral drugs acyclovir and ganciclovir are prepared according to
the procedures in Preparation 1, except that the nonwater soluble
hydroattractant used is, respectively, microcrystalline cellulose
(Avicel), cross-linked sodium or calcium carboxymethyl cellulose,
cellulose fiber (Solka-Floc, Arbocel, Elcema), cross-linked
polyvinyl pyrrolidone (Polyplasdone XL), cross-linked Amberlite
resin, alginates (Satialgine), colloidal magnesium-aluminum
silicate (Veegum), corn starch granules, rice starch granules,
potato starch granules, and sodium carboxymethyl starch (Expotab,
Primojel). The prepared dosage forms are retained in the stomach of
a subject and deliver active agent over a prolonged period of
time.
EXAMPLE 5
[0133] The following active agents are substituted, in the
quantities indicated in the parentheses following each active agent
listed, for the quantity of acyclovir in Preparation 1: cimetidine
(400 mg; 800 mg, 1200 mg, 1600 mg), ranitidine (150 mg; 200 mg, 300
mg), captopril (12.5 mg; 25 mg; 50 mg; 100 mg, 150 mg), methyldopa
(125; 250; 500 mg), and selegiline (5 mg, 10 mg) and the dosage
forms are prepared in the same manner as described in Preparation
1. The prepared dosage forms are retained in the stomach of a
subject and deliver active agent over a prolonged period of
time.
EXAMPLE 6
[0134] Dosage forms of this invention containing 600 mg of
acyclovir are fabricated according to the procedures of Preparation
1, except that the tablet is inserted into a size "00" hard gelatin
capsule before banding. The band is applied by a printing process
using the methods and compositions described in U.S. Pat. No.
5,534,263, incorporated herein by reference, where the band
material is ethyl acrylate/methyl methacrylate 70:30 copolymer
applied as an aqueous latex (Eudragit NE 30 D, Rohm Tech). The
banding material may be formulated with 30% by weight of a
plasticizer, such as triacetin. Optionally, an amount of organic
solvent such as ethyl alcohol or isopropyl alcohol may be blended
into the aqueous latex to promote good band formation and rapid
drying of the latex after application. The resulting dosage forms
are smooth and easy to swallow.
EXAMPLE 7
[0135] A gastric platform dosage form of the antihistamine drug,
fexofenadine hydrochloride, is prepared according to the following
procedures. The active agent layer is prepared from 11.5 grams of
the drug, 30 grams of polyethylene oxide, 54 grams of
low-substituted hydroxypropyl cellulose, and 3.7 grams of polyvinyl
pyrrolidone by individually passing those materials through a sieve
having 40 wires per inch, and then tumble mixing the three
components together for 10 minutes. The polyethylene oxide
(Polyox.RTM. WSR-N-60K as supplied by Union Carbide, Danbury,
Conn.) has a molecular weight of approximately 2 million grams per
mole, the polyvinyl pyrrolidone (Povidone K2932 as supplied by GAF
Corporation, New York, N.Y.) has a molecular weight of
approximately 45,000 grams per mole and the hydroxypropyl cellulose
(LHPC-11 supplied by Shin-Etsu Chemical Company, Tokyo, Japan) has
a hydroxypropyl content of approximately 11 weight percent.
Anhydrous ethyl alcohol formula SDA 3A is slowly added to the dry
mixture with stirring until a uniform damp mass is formed. The damp
mass is forced thorough a sieve with 20 wires per inch, forming
elongated granules which are then air dried at ambient room
conditions overnight. The resulting dried granules are then passed
through the 20 mesh sieve forming more rounded granules. Then, 0.30
grams of the flow-promoting agent, colloidal silicon dioxide
(Aerosile200 supplied by Degussa Inc, New York, N.Y.), is dry mixed
into the blend. Finally, 0.5 grams of the tableting lubricant,
magnesium stearate, previously passed through a sieve having 60
wires per inch, is tumble blended into the bulk. This produced the
final granulation for the active agent layer.
[0136] The highly swellable layer is prepared from 99% polyethylene
oxide (Polyox 303) and 1% ferric oxide by tumble mixing those
components for approximately 10 minutes. The anhydrous ethyl
alcohol formula SDA 3A is slowly added to form a damp mass that is
forced through a sieve with 20 wires per inch and dried overnight
under ambient conditions.
[0137] Individual portions of the drug granulation weighing
approximately 522 mg and of the highly swellable, retention layer
granulation weighing approximately 522 mg each are separately
compressed with size 0 caplet tooling on a Carver press with a
force of about 1.5 tons to form a bilayer, laminated tablet core.
Each tablet contains about 120 mg of fexofenadine
hydrochloride.
[0138] A solution for use in film coating the tablets is then
prepared by stirring 40 grams of methyl cellulose (Methocel A15 LV
Premium supplied by Dow Chemical, Midland Mich.) and 10 grams of
sorbitol in 950 grams of purified water at room temperature. The
mixture is chilled overnight at 9.degree. centigrade to complete
dissolution. The tablets from above are then transferred to a
pharmaceutical coating pan, and spray coated with the solution in a
current of warmed air until a dry film coating weight of about 37
mg is deposited onto each tablet. The film coated tablet cores are
then dried in a forced air oven at 40 degrees Centigrade
overnight.
[0139] An aqueous dispersion for use in banding the tablets is
prepared by dissolving 30 grams of triacetin in 174.75 grams of
ethyl acrylate methylmethacrylate 70:30 copolymer aqueous
dispersion (Eudragit.RTM. NE40D supplied by Rohm Corporation,
Darmstadt, West Germany). Then, 0.1 grams of anti-foam agent
(Simethicone Q7-2587, Dow Chemical, Midland, Mich.) is blended into
the mixture. This forms the final composition of the banding
dispersion.
[0140] The dried film coated tablets from above are then banded by
applying the above banding dispersion in a transfer printing
process using a printing wheel having a width of approximately 100
mils (2.54 mm). The freshly banded system is then dried in warm air
to remove the water from the aqueous dispersion, leaving a single
band located in the center of the caplet having a width of
approximately 120 mils (3.05 mm) and a weight of approximately 21
mg. The entire banded system is then overcoated with more of the
aqueous-based film coat solution using the formulation and process
as described above until a film coat weight of about 31 mg is
applied. This completes fabrication of the dosage form.
EXAMPLE 8
[0141] A gastric platform dosage form delivering the antibiotic,
minocylcine, for treatment of Helicobacter pylori gastritis,
gastric and duodenal ulcers, with a single core layer is fabricated
and compared to a bilayer core system of this invention. The
procedures for fabrication are similar to those specified in
EXAMPLE 7. For the single layer dosage form, 17.8 grams of
minocycline hydrochloride, 24.6 gams of polyethylene oxide 53.8
grams of low-substituted hydroxypropyl cellulose, 3 grams of
polyvinyl pyrrolidone 0.3 grams of colloidal silicon dioxide, and
0.5 grams of magnesium stearate are granulated according to the
procedures in EXAMPLE 7. The excipients are the same as in this
example except the polyethylene oxide had a molecular weight of
approximately 4 million grams per mole (Polyox WSR 301). The
granulation is compressed into caplets weighing approximately 1042
mg where each tablet contains a unit dose of about 185 mg of
minocycline hydrochloride. The tablets are film subcoated with a
coating weight of 52 mg, banded with a 21 mg band, and overcoated
with 21 mg of film. The compositions of the subcoat, band, and
overcoat are the same as disclosed in EXAMPLE 7.
[0142] The bilayer dosage form is prepared using the granulation
procedures of EXAMPLE 7. 35.4 Grams of minocycline hydrochloride,
22.0 grams of Polyox WSR-301, 39 grams of low-substituted
hydroxypropyl cellulose, 2.8 grams of polyvinyl pyrrolidone K2932
are wet granulated. 0.3 Grams of Aerosil silicon dioxide and 0.5
grams of magnesium stearate are dry mixed into the blend, producing
the finished drug layer granulation. The retention layer is
prepared by passing 80 grams of Polyox WSR-303 and 20 grams of
powdered cellulose Solka Floc 900 (Fiber Sales and Development
Corporation, Urbana, Ohio) through a 40 mesh screen and the
components are tumbled mixed for about 10 minutes. Denatured
ethanol formula 3A is added with stirring to form a uniform damp
mass, which is then forced through a 20 mesh sieve. The resulting
granules are air dried overnight, then passed again through the 20
mesh sieve, producing the high-swelling, retention layer
granulation. Then, the drug layer granulation and the retention
layer granulation are compressed into biayer caplets consisting of
a drug layer of 522 mg and a retention layer of 522 mg. The bilayer
tablets are film coated and banded according to the compositions
and procedures described in EXAMPLE 7. Each dosage form, i.e.,
bilayer tablet, contained 185 mg of minocycline hydrochloride.
[0143] The resulting single layer and bilayer dosage forms are
compared in vivo as follows: A single layer dosage form is
administered to each of three dogs in the fed state. Plasma samples
are collected periodically over the 48-hour period post dosing. The
concentration of the minocycline hydrochloride in the samples is
then measured by high pressure liquid chromatography and recorded.
After a suitable wash-out period of two weeks, the bilayer dosage
forms were administered to the dogs and tested under the same
conditions. The results of the study are presented in FIG. 7. The
square symbols depicted in the graph correspond to the plasma
concentration profile of drug generated by the single layer dosage
form and the triangular symbols correspond to the plasma
concentration profile of drug generated by the bilayer dosage form.
The bilayer dosage form exhibits a multifold increase in drug
bioavailability (as measured by the area under the curve; "AUC")
and a more elevated plasma concentration compared to the single
layer dosage form without the retention layer. The calculated AUC
of the bilayer dosage form was 119.+-.26 .mu.g hr/ml and the
calculated AUC of the monolayer dosage forms was 28.1.+-.21 .mu.g
hr/ml.
EXAMPLE 9
[0144] Dosage forms of the invention are prepared in accordance
with the procedure of Example 7 having the following components and
composition (all percentages are weight percent): The active agent
layer (522 mg) contains 23% fexofenadine hydrochloride, 24.2% of
Polyox WSR N-60K, 50% LHPC (low substituted
hydroxypropylcellulose), 2% polyvinylpyrrolidone (PVPK 2932), 0.3%
silicon dioxide (Aerosil 200) and 0.5% magnesium stearate. The
highly-swellable layer (522 mg) contains 99% Polyox 303 and 1% red
ferric oxide. The first overcoat (33 mg) contains 80% Methocel
AI5LV Premium and 20% sorbitol. The banding material (21 mg)
contains 69.9% Eudragit NE 40D (dry weight basis), 30% triacetin
and 0.1% simethicone Q7-2587. The final overcoat (28 mg) contains
80% Methocel A15LV and 20% sorbitol. The release rate and
cumulative release for representative dosage forms is presented in
FIGS. 8A and 8B, respectively. The dosage forms exhibit a mean
release rate of about 10.4 mg/hour and a T.sub.90, time to deliver
90% of the amount of active agent in the dosage form, of about 10.3
hours.
EXAMPLE 10
[0145] Dosage forms are prepared in accordance with Examples 7 and
9 except that Polyox 301K is substituted for the Polyox WSR N-60K
in the drug layer. The release rate and cumulative release of
fexofenadine hydrochloride is presented in FIGS. 9A and 9B
respectively. Representative dosage forms exhibit a mean release
rate of about 7.4 mg/hour and a T.sub.90 of about 13.8 hours.
EXAMPLE 11
[0146] This example illustrates the identification and evaluation
of compositions of the high-swelling layer. Formulation 1 was
prepared by passing 25 grams of polyethylene oxide and 25 grams of
cellulose fiber through a sieve with 4 wires per inch. The
resulting mixture was tumble mixed in a V-blender for 10 minutes.
The polyethylene oxide had a molecular weight of approximately 7
million grams per mole (Polyox 303). The cellulose fiber had an
average fiber length of 110 microns and is supplied under the trade
name SOLKA-FLOC 900FCC. The mixed powders were then transferred to
a beaker where anhydrous ethyl alcohol formula SDA3A was added with
stirring to form a uniform damp mass. The resulting damp mass was
forced through a sieve with 20 wires per inch, producing elongated
granules. The granules were then air dried overnight at ambient
room conditions. The resulting dried granules were then forced with
a spatula through the 20-mesh sieve to produce Granulation 1. A
portion of Granulation 1 weighting 1.04 grams was filled into a
punch and die set mounted on a Carver press. The tooling was caplet
shaped, with major axis dimension of 0.85 inch (21.6 mm) and a
minor axis dimension of 0.3 inch (7.6 mm). The caplet was
compressed using a pressure head of 1.5 tons.
[0147] The swelling properties of the resulting caplet 1 were then
evaluated in vitro. The caplet was placed in 900 ml of simulated
gastric fluid therostated at 37.degree. C. The gastric fluid had a
pH value of 1.2 and was prepared according to the formula, but
without enzyme, as specified in the US Pharmacopeia 23/National
Formulary 18, page 2053. The compact was tested in this fluid using
the paddle test apparatus described on page 1792 of the same
reference. The paddle speed was maintained at 212 revolutions per
minute to simulate mechanical insult and abrasion in vivo in the
environment of use. After 30 minutes of testing in these
conditions, the caplet was removed. The dimension of the minor axis
was measure using an optical inspection system (RAM Optical
Instrumentation, Huntington Beach, Calif.). The percent increase in
the minor axis dimension was then calculated. The swollen caplet
was then returned to the testing bath. After another 30 minutes in
the bath under test conditions, the caplet was removed and the
dimensions were again measured and the percent increase in the
minor axis was again calculated. Each calculation was based o the
dimension of minor axis at time zero, i.e., 7.6 mm. This process
was continued hourly for the next four hours. The percent increase
in minor axis dimension was plotted as a function of test time and
the results are represented by the diamond-shaped symbols in FIG.
10.
[0148] Three other caplets having different compositions were
prepared and tested according to the procedures described above.
Formulation 2 consisted of 25 grams of Polyox 303, 12.5 grams of
Solka-Floc 900FCC, and 12.5 grams of sodium chloride. The
dimensional changes of this caplet as a function of time are
represented by hexagonal symbols in FIG. 10 The rate and extent of
swelling of Formulation 1 and Formulation 2 were similar. Both
increased in minor axis dimension by about 75% at a time of one
hour and both swelled to about 140% by a time of 5 hours.
Formulation 2 had a higher bulk density than Formulation 1 and
flowed and filled die cavities more quickly, thus making it
preferable for use in high speed tableting operations.
[0149] Formulation 3 consisted of 25 grams of Polyox 303 and 25
grams of sodium chloride. The results of swelling of the caplet
formed of this formulation is illustrated in FIG. 10 by the open
circular symbols. Swelling of this caplet at one hour was
comparable to that of Formulations 1 and 2, but this caplet did not
swell to the extent of the caplets formed from Formulations 1 and 2
at the end of the five hour period. Formulation 4 consisted of 50
grams of Polyox 303. Swelling behavior of the caplet of this
granulation is represented by the curve with the closed circles in
FIG. 10. Formulation 4 swelled more slowly and to a lesser extent
than Formulations 1 and 2. The results demonstrate that the
presence of cellulosic fibers increases the rate and extent of the
swelling process over formulations that do not include the fibers.
Also, the presence of the sodium chloride provides a granulation
bulk density that is more suitable for high speed tableting
processes than formulations without the sodium chloride.
[0150] The present invention is described and characterized by one
or more of the following technical features and/or characteristics,
either alone or in combination with one or more of the other
features and characteristics: an active agent dosage form adapted
for gastric retention comprising: (a) a first layer comprising a
swellable, water-soluble polymer; (b) a second layer comprising a
therapeutically-effective amount of an active agent, the second
layer being laminated with the first layer at a common surface, and
(c) at least one band of insoluble material circumscribing and
binding together the first layer and the second layer, the first
layer being adapted to swell in the stomach to facilitate retention
of the dosage form in the stomach over a prolonged period of time,
wherein the release of the active agent from the second layer is
independent of the composition of the first layer and occurs over a
prolonged period of time; a dosage form wherein the number average
molecular weight of the water-soluble polymer is between about
100,000 and 20,000,000 grams per mole; a dosage form wherein the
water soluble polymer is polyethylene oxide, hydroxypropyl
cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose,
sodium carboxy methylcellulose, calcium carboxymethyl cellulose,
methyl cellulose, polyacrylic acid, maltodextrin, pre-gelatinized
starch, guar gum, sodium alginate, or polyvinyl alcohol; a dosage
form wherein the second layer comprises a hydroattractant selected
from low-substituted hydroxypropyl cellulose, microcrystalline
cellulose, cross-linked sodium or calcium carboxymethyl cellulose,
cellulose fiber, cross-linked polyvinyl pyrrolidone, cross-linked
polyacrylic acid, cross-linked Amberlite resin, alginates,
colloidal magnesium-aluminum silicate, corn starch granules, rice
starch granules, potato starch granules and sodium carboxymethyl
starch, and the first layer optionally comprises a hydroattractant
selected from low-substituted hydroxypropyl cellulose,
microcrystalline cellulose, cross-linked sodium or calcium
carboxymethyl cellulose, cellulose fiber, cross-linked polyvinyl
pyrrolidone, cross-linked polyacrylic acid, cross-linked Amberlite
resin, alginates, colloidal magnesium-aluminum silicate, corn
starch granules, rice starch granules, potato starch granules and
sodium carboxymethyl starch; a dosage form wherein the first layer
swells more rapidly and to a greater extent than does the second
layer; a dosage form wherein the active agent is. an antiviral,
antimicrobial, antidiabetic, antihperglycemic, hypoglycemic,
antidepressant, antiobesity or antifingal active agent; a dosage
form wherein the weight percent of the water soluble polymer in the
second layer is 5 to 99.99 weight percent and weight percent of the
hydroattractant in the second layer is 0 to 60 weight percent; a
dosage form wherein the prolonged time period is at least 3 hours;
a dosage form wherein the prolonged time period is between about 6
to 12 hours; a dosage form wherein the first layer comprises
polyethylene oxide having a number average molecular weight of at
least 100,000 grams per mole; a dosage form wherein the active
agent is acyclovir, ganciclovir, ritonavir, minocycline,
cimetidine, ranitidine, captopril, methyldopa, selegiline,
minocycline, fexofenadine, metformin, bupropion, orlistat or a
pharmaceutically acceptable salt thereof; a dosage form wherein the
second layer comprises an active agent selected from the group
consisting of acyclovir, ganciclovir, ritonavir, metformin,
bupropion, orlistat and minocycline, and the second layer comprises
a bioerodible polymer, a therapeutically effective amount of the
active agent being delivered to the stomach of a subject over at
least a 3 hour period; a method of treating a subject in need
thereof with an active agent that comprises administering to the
subject a multilayered dosage form adapted to be retained in the
stomach over a prolonged period of time, the dosage form comprising
a second layer adapted to swell in the stomach of the subject and
retain the dosage form in the stomach for a prolonged period of
time, and a first layer adapted to deliver to the subject an active
agent at a variable rate of delivery; a method which comprises
administering one or more dosage forms to the subject in the fed
state at the start of each dosing period; a method wherein the
administration of the dosage form occurs within one hour of the
subject consuming food; a dosage form comprising a gastric-emptying
delaying agent; a dosage form wherein the gastric-emptying delaying
agent is selected from anticholonergic agents, methylcellulose,
guar gum, fats and fatty acids of 10-15 carbon atoms; a dosage form
wherein the active agent comprises a liquid, active agent
formulation; a dosage form wherein the liquid, active agent
formulation is sorbed into porous particles; a dosage form wherein
the porous particles are calcium hydrogen phosphate or magnesium
aluminometasilicate; a dosage form comprising a pH regulating agent
or a chelating agent; a dosage form wherein the liquid, active
agent formulation comprises a pH regulating agent selected from
organic and inorganic acids and bases, a dosage form wherein the
liquid, active agent formulation comprises a chelating agent.
[0151] The above description has been given for ease of
understanding only. No unnecessary limitations should be understood
therefrom, as modifications will be obvious to those skilled in the
art.
* * * * *