U.S. patent application number 14/075105 was filed with the patent office on 2014-03-06 for high shear application in drug delivery.
This patent application is currently assigned to H R D Corporation. The applicant listed for this patent is H R D Corporation. Invention is credited to Rayford G. ANTHONY, Abbas HASSAN, Aziz HASSAN.
Application Number | 20140066852 14/075105 |
Document ID | / |
Family ID | 44858409 |
Filed Date | 2014-03-06 |
United States Patent
Application |
20140066852 |
Kind Code |
A1 |
HASSAN; Abbas ; et
al. |
March 6, 2014 |
HIGH SHEAR APPLICATION IN DRUG DELIVERY
Abstract
In this disclosure, methods and systems for drug delivery
utilizing high shear are disclosed. In an embodiment, a method
comprises (1) subjecting a therapeutic fluid containing a drug to
high shear; and (2) obtaining a processed therapeutic fluid,
wherein the processed therapeutic fluid contains the drug in
nano-size. In an embodiment, a method comprises (1) subjecting a
drug carrier and a therapeutic fluid containing a drug to high
shear; and (2) obtaining a processed therapeutic fluid, wherein the
processed therapeutic fluid contains the drug carrier loaded with
the drug. In an embodiment, a method comprises (1) applying high
shear to a drug carrier and a therapeutic fluid containing a drug;
(2) obtaining a processed therapeutic fluid, wherein the processed
therapeutic fluid contains the drug-loaded carrier; and (3)
modifying the drug-loaded carrier with a targeting moiety to obtain
a modified drug-loaded carrier.
Inventors: |
HASSAN; Abbas; (Sugar Land,
TX) ; HASSAN; Aziz; (Sugar Land, TX) ;
ANTHONY; Rayford G.; (College Station, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
H R D Corporation |
Sugar Land |
TX |
US |
|
|
Assignee: |
H R D Corporation
Sugar Land
TX
|
Family ID: |
44858409 |
Appl. No.: |
14/075105 |
Filed: |
November 8, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13082905 |
Apr 8, 2011 |
8609115 |
|
|
14075105 |
|
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61330104 |
Apr 30, 2010 |
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61355448 |
Jun 16, 2010 |
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Current U.S.
Class: |
604/151 ;
366/145; 366/182.2 |
Current CPC
Class: |
B01F 7/00766 20130101;
A61M 5/142 20130101; A61P 23/00 20180101; A61J 3/00 20130101; B01F
13/1016 20130101; A61P 31/18 20180101; A61K 9/0019 20130101; A61P
9/00 20180101; A61P 29/00 20180101; A61P 25/28 20180101; A61P 35/00
20180101; B01F 7/008 20130101 |
Class at
Publication: |
604/151 ;
366/182.2; 366/145 |
International
Class: |
B01F 7/00 20060101
B01F007/00; A61M 5/142 20060101 A61M005/142 |
Claims
1. A system comprising: a high shear device configured to subject a
feed comprising a therapeutic fluid, a drug, and optionally a drug
carrier to high shear, thus forming a processed therapeutic fluid;
and a pump fluidly connected with the high shear device, and
configured to control the flow rate and residence time of a fluid
passing through the high shear device.
2. The system of claim 1 wherein a fluid passage through the high
shear device and the pump is sterile.
3. The system of claim 1 further comprising at least one
temperature control unit configured to control the temperature
within the high shear device.
4. The system of claim 3 wherein the at least one temperature
control unit is configured to maintain the temperature at a
temperature in the range of from about 0.degree. F. to about
100.degree. F..+-.2.degree. F.
5. The system of claim 1 further comprising at least one product
storage vessel downstream from and in fluid communication with the
high shear device, and configured for storage of the processed
therapeutic fluid.
6. The system of claim 5 further comprising at least one
temperature control unit selected from temperature control units
configured to control the temperature within the high shear device,
and temperature control units configured to control the temperature
within the product storage vessel.
7. The system of claim 6 wherein the at least one temperature
control unit is configured to maintain the temperature at a
temperature in the range of from about 0.degree. F. to about
100.degree. F..+-.2.degree. F.
8. The system of claim 1 further comprising at least one device
configured for intravenous administration of said processed
therapeutic fluid to a patient.
9. The system of claim 1 further comprising one or more feed
storage vessel configured for storage of one or more feed component
selected from the group consisting of the therapeutic fluid, the
drug, and the optional drug carrier.
10. The system of claim 9 wherein the one or more feed storage
vessel contains the one or more feed component.
11. The system of claim 1 further comprising one or more apparatus
configured to modify the processed therapeutic fluid prior to
administration thereof to a patient.
12. The system of claim 11 wherein the one or more apparatus
configured to modify the therapeutic fluid comprises at least one
apparatus selected from the group consisting of concentrators
configured to increase the concentration of the drug relative to
the concentration of the drug in the processed therapeutic fluid,
thus providing a concentrated therapeutic fluid,
extraction/purification apparatus configured to extract therapeutic
fluid from the processed therapeutic fluid, thus leaving a
drug-loaded carrier, and apparatus configured to do both.
13. The system of claim 1 wherein the high shear device is operable
to produce a processed therapeutic fluid containing the drug in
nano-size.
14. The system of claim 1 wherein the high shear device is operable
to produce a processed therapeutic fluid containing the drug in
sub-nano size.
15. The system of claim 1 wherein the feed comprises a drug
carrier, and wherein the processed therapeutic fluid contains the
drug carrier loaded with the drug.
16. The system of claim 15 further comprising extraction apparatus
configured to extract therapeutic fluid from the processed
therapeutic fluid, thus leaving the drug carrier loaded with the
drug.
17. The system of claim 15 further comprising apparatus configured
for modifying the drug-loaded carrier with a targeting moiety to
obtain a modified drug-loaded carrier.
18. The system of claim 1 wherein the high shear device is
configured to subject the feed to a shear rate of at least 20,000
s.sup.-1.
19. The system of claim 1 wherein the high shear device comprises
at least one generator, wherein the at least one generator
comprises a rotor and a complementarily-shaped stator.
20. The system of claim 19 wherein the rotor is toothed.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application which claims
the benefit under 35 U.S.C. .sctn.121 of U.S. patent application
Ser. No. 13/082,905 filed Apr. 8, 2011, which claims the benefit
under 35 U.S.C. .sctn.119(e) of U.S. Provisional Patent
Applications No. 61/330,104 filed Apr. 30, 2010, and 61/355,448
filed Jun. 16, 2010; the disclosure of each of said applications is
hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to drug delivery.
More particularly, the present invention relates to utilizing a
shear device to apply suitable shear stress to therapeutic fluids
for drug delivery.
BACKGROUND
[0003] Drug delivery is the method or process of administering a
pharmaceutical compound to achieve a therapeutic effect in humans
or animals. Different delivery mechanisms may alter drug release
profile, absorption, distribution, and elimination for the benefit
of improving product efficacy and safety, as well as patient
convenience and compliance. Most common methods of delivery include
the preferred non-invasive peroral (through the mouth), topical
(skin), transmucosal (nasal, buccal/sublingual, vaginal, ocular and
rectal), and inhalation routes. Injection or infusion is used to
deliver medications such as peptides, proteins, antibodies,
vaccines, and gene based drugs because such medications are
generally susceptible to enzymatic degradation or are unable to be
absorbed into the systemic circulation efficiently due to their
molecular size and charge for therapeutic efficacy. For example,
many immunizations are based on the delivery of protein drugs and
are often done by injection.
[0004] Targeted drug delivery or targeted delivery is one of the
areas in drug delivery that has drawn immense attention. The basic
concept is to develop delivery mechanisms that cause the drug to be
active only in a particular target area of the body (for example,
in cancerous tissues). Sustained release formulation is another
area in which the drug is released over a period of time in a
controlled manner from a formulation. Sustained release
formulations often include the use of liposomes, biodegradable
microspheres, and drug-polymer conjugates.
[0005] Drug delivery remains one of the most complex, intriguing,
and exciting research areas in industry, medicine, science, and
technology. Therefore there is an ongoing need and interest to
develop new methods and systems to improve drug delivery in various
aspects.
SUMMARY
[0006] In an embodiment, a method is disclosed. The method
comprises (1) subjecting a therapeutic fluid containing a drug to
high shear; and (2) obtaining a processed therapeutic fluid,
wherein the processed therapeutic fluid contains the drug in
nano-size. In various embodiments, the drug is in the form of a
solid, liquid, gas, solution, gel, emulsion, powder, or a
combination thereof. In some embodiments, the method further
comprises controlling the shear rate to which therapeutic fluid is
subjected. In some embodiments, the method further comprises
controlling the period of time that the therapeutic fluid is
subjected to high shear. In some embodiments, the drug in nano-size
has improved efficacy when administered to a patient. In some
embodiments, subjecting the therapeutic fluid containing the drug
to high shear comprises creating free radicals of the drug.
[0007] In an embodiment, a method is described. The method
comprises (1) subjecting a drug carrier and a therapeutic fluid
containing a drug to high shear; and (2) obtaining a processed
therapeutic fluid, wherein the processed therapeutic fluid contains
the drug carrier loaded with the drug. In some embodiments, the
method further comprises administering the processed therapeutic
fluid to a patient. In some embodiments, subjecting the drug
carrier and the therapeutic fluid containing the drug to high shear
creates an interaction between the drug carrier and the drug or
enhances the interaction between the drug carrier and the drug. In
some embodiments, subjecting the drug carrier and the therapeutic
fluid containing the drug to high shear improves the loading
capacity of the drug carrier for the drug.
[0008] In an embodiment, a method is disclosed. The method
comprises (1) applying high shear to a drug carrier and a
therapeutic fluid containing a drug; (2) obtaining a processed
therapeutic fluid, wherein the processed therapeutic fluid contains
the drug-loaded carrier; and (3) modifying the drug-loaded carrier
with a targeting moiety to obtain a modified drug-loaded carrier.
In some embodiments, the method further comprises concentrating the
processed therapeutic fluid containing the drug-loaded carrier. In
some embodiments, the method further comprises purifying the
drug-loaded carrier from the processed therapeutic fluid. In some
embodiments, the method further comprises administering the
modified drug-loaded carrier to a patient. In some cases, the
modified drug-loaded carrier is used to treat cancer patients.
[0009] In an embodiment, a system is described. The system
comprises (1) a high shear device; and (2) a pump configured to
control the flow rate and residence time of a fluid passing through
the high shear device. In various embodiments, the fluid passage of
the system is sterile. In some embodiments, the system further
comprises at least one temperature control unit configured to
control the temperature of the high shear device. In some
embodiments, the system further comprises at least one storage
vessel in fluid communication with the high shear device. In some
embodiments, the system further comprises at least one device
configured for intravenous administration of the fluid to a
patient.
[0010] The foregoing has outlined rather broadly the features and
technical advantages of the invention in order that the detailed
description of the invention that follows may be better understood.
Additional features and advantages of the invention will be
described hereinafter that form the subject of the claims of the
invention. It should be appreciated by those skilled in the art
that the conception and the specific embodiments disclosed may be
readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the invention. It
should also be realized by those skilled in the art that such
equivalent constructions do not depart from the spirit and scope of
the invention as set forth in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] For a more detailed description of the preferred embodiment
of the present invention, reference will now be made to the
accompanying drawings, wherein:
[0012] FIG. 1A is a longitudinal cross-section view of a one-stage
shear device.
[0013] FIG. 1B is a longitudinal cross-section view of a
three-stage shear device.
[0014] FIG. 2A illustrates a method of utilizing a shear device for
drug delivery.
[0015] FIG. 2B is a process flow diagram demonstrating the
application of shear stress for drug delivery.
[0016] FIG. 3A illustrates a method of utilizing a shear device in
conjunction with a drug carrier for drug delivery.
[0017] FIG. 3B is a process flow diagram demonstrating the
application of shear stress in conjunction with a drug carrier for
drug delivery.
[0018] FIG. 4A illustrates a method of utilizing a shear device in
conjunction with a drug carrier and drug carrier modification for
drug delivery.
NOTATION AND NOMENCLATURE
[0019] As used herein, the term "therapeutic fluids" refers to
dispersions that contain at least one substance that has
therapeutic effects (i.e., drug). Some examples of these substances
are neurological drugs, anti-inflammatory drugs, anti-cancer drugs,
antibiotics, therapeutic gases (e.g., ozone, sulfur based gases,
carbon monoxide, oxygen, hydrogen), viral vectors, genes, proteins,
polymers, liposomes, organic particles, inorganic particles (e.g.
minerals). Such substances/drugs may be a gas, a liquid, a gel, or
a solid.
[0020] As used herein, the term "dispersion" refers to a liquefied
mixture that contains at least two distinguishable substances (or
"phases") that either will or will not readily mix and dissolve
together. As used herein, a "dispersion" comprises a "continuous"
phase (or "matrix"), which holds therein discontinuous droplets,
bubbles, and/or particles of the other phase or substance. The term
dispersion may thus refer to foams comprising gas bubbles suspended
in a liquid continuous phase, emulsions in which droplets of a
first liquid are dispersed throughout a continuous phase comprising
a second liquid with which the first liquid is miscible or
immiscible, and continuous liquid phases throughout which solid
particles are distributed. As used herein, the term "dispersion"
encompasses continuous liquid phases throughout which gas bubbles
are distributed, continuous liquid phases throughout which solid
particles are distributed, continuous phases of a first liquid
throughout which droplets of a second liquid that is soluble or
insoluble in the continuous phase are distributed, and liquid
phases throughout which any one or a combination of solid
particles, miscible/immiscible liquid droplets, and gas bubbles are
distributed. Hence, a dispersion can exist as a homogeneous mixture
in some cases (e.g., liquid/liquid phase), or as a heterogeneous
mixture (e.g., gas/liquid, solid/liquid, or gas/solid/liquid),
depending on the nature of the materials selected for
combination.
[0021] Certain terms are used throughout the following description
and claims to refer to particular system components. This document
does not intend to distinguish between components that differ in
name but not function.
[0022] In the following description and in the claims, the terms
"including" and "comprising" are used in an open-ended fashion, and
thus should be interpreted to mean "including, but not limited to .
. . ".
DETAILED DESCRIPTION
Shear Device
[0023] Shear device is a mechanical device that utilizes one or
more generator comprising a rotor/stator combination, each of which
has a gap between the stator and rotor. The gap between the rotor
and the stator in each generator set may be fixed or may be
adjustable. Shear device is configured in such a way that it is
capable of producing submicron and micron-sized bubbles or
nano-size particles in a mixture flowing through the high shear
device. The high shear device comprises an enclosure or housing so
that the pressure and temperature of the mixture may be
controlled.
[0024] High shear mixing devices are generally divided into three
general classes, based upon their ability of mixing/dispersing.
Mixing is the process of reducing the size of particles or
inhomogeneous species within the fluid. One metric for the degree
or thoroughness of mixing is the energy density per unit volume
that the mixing device generates to disrupt the fluid particles.
The classes are distinguished based on delivered energy densities.
Three classes of industrial mixers having sufficient energy density
to consistently produce mixtures or emulsions with particle sizes
in the range of submicron to 50 microns include homogenization
valve systems, colloid mills and high speed mixers. In the first
class of high energy devices, referred to as homogenization valve
systems, fluid to be processed is pumped under very high pressure
through a narrow-gap valve into a lower pressure environment. The
pressure gradients across the valve and the resulting turbulence
and cavitation act to break-up any particles in the fluid. These
valve systems are most commonly used in milk homogenization and can
yield average particle sizes in the submicron to about 1 micron
range.
[0025] At the opposite end of the energy density spectrum is the
third class of devices referred to as low energy devices. These
systems usually have paddles or fluid rotors that turn at high
speed in a reservoir of fluid to be processed, which in many of the
more common applications is a food product. These low energy
systems are customarily used when average particle sizes of greater
than 20 microns are acceptable in the processed fluid.
[0026] Between the low energy devices and homogenization valve
systems, in terms of the mixing energy density delivered to the
fluid, are colloid mills and other high speed rotor-stator devices,
which are classified as intermediate energy devices. A typical
colloid mill configuration includes a conical or disk rotor that is
separated from a complementary, liquid-cooled stator by a
closely-controlled rotor-stator gap, which is commonly between
0.0254 mm to 10.16 mm (0.001-0.40 inch). Rotors are usually driven
by an electric motor through a direct drive or belt mechanism. As
the rotor rotates at high rates, it pumps fluid between the outer
surface of the rotor and the inner surface of the stator, and shear
forces generated in the gap process the fluid. Many colloid mills
with proper adjustment achieve average particle sizes of 0.1-25
microns in the processed fluid. These capabilities render colloid
mills appropriate for a variety of applications including colloid
and oil/water-based emulsion processing such as that required for
cosmetics, mayonnaise, or silicone/silver amalgam formation, to
roofing-tar mixing.
[0027] Tip speed is the circumferential distance traveled by the
tip of the rotor per unit of time. Tip speed is thus a function of
the rotor diameter and the rotational frequency. Tip speed (in
meters per minute, for example) may be calculated by multiplying
the circumferential distance transcribed by the rotor tip, 2.pi.R,
where R is the radius of the rotor (meters, for example) times the
frequency of revolution (for example revolutions per minute, rpm).
A colloid mill, for example, may have a tip speed in excess of 22.9
m/s (4500 ft/min) and may exceed 40 m/s (7900 ft/min). For the
purpose of this disclosure, the term `high shear` refers to
mechanical rotor stator devices (e.g., colloid mills or
rotor-stator dispersers) that are capable of tip speeds in excess
of 5.1 m/s. (1000 ft/min) and require an external mechanically
driven power device to drive energy into the feed stream to be
processed. For example, in a shear device, a tip speed in excess of
22.9 m/s (4500 ft/min) is achievable, and may exceed 40 m/s (7900
ft/min). In some embodiments, a shear device is capable of
delivering at least 300 L/h at a tip speed of at least 22.9 m/s
(4500 ft/min). The power consumption will vary depending on the
viscosity, temperature and pressure of operation. Shear device
combines high tip speed with a very small shear gap to produce
significant shear on the material being processed. The amount of
shear will be dependent on the viscosity of the fluid. Accordingly,
a local region of elevated pressure and temperature is created at
the tip of the rotor during operation of the high shear device. In
some cases the locally elevated pressure is about 1034.2 MPa
(150,000 psi). In some cases the locally elevated temperature is
about 500.degree. C. In some cases, these local pressure and
temperature elevations may persist for nano or pico seconds.
[0028] Without wishing to be limited to a particular theory, it is
believed that the level or degree of high shear mixing is
sufficient to produce localized non-ideal conditions. Localized
non-ideal conditions are believed to occur within the high shear
device resulting in increased temperatures and pressures with the
most significant increase believed to be in localized pressures.
The increase in pressures and temperatures within the high shear
device are instantaneous and localized and quickly revert back to
bulk or average system conditions once exiting the high shear
device. In some cases, the high shear mixing device induces
cavitation of sufficient intensity to dissociate one or more of the
feed stream components into free radicals, which may intensify an
interaction (e.g., a chemical reaction) or allow an interaction to
take place at less stringent conditions than might otherwise be
required. Cavitation may also increase rates of transport processes
by producing local turbulence and liquid micro-circulation
(acoustic streaming). An overview of the application of cavitation
phenomenon in chemical/physical processing applications is provided
by Gogate et al., "Cavitation: A technology on the horizon,"
Current Science 91 (No. 1): 35-46 (2006).
[0029] An approximation of energy input into the fluid (kW/L/min)
can be estimated by measuring the motor energy (kW) and fluid
output (L/min). As mentioned above, tip speed is the velocity
(ft/min or m/s) associated with the end of the one or more
revolving elements that is creating the mechanical force applied to
the feed stream components. In embodiments, the energy expenditure
of shear device is greater than 1000 W/m.sup.3. In embodiments, the
energy expenditure of shear device is in the range of from about
3000 W/m.sup.3 to about 7500 W/m.sup.3.
[0030] The shear rate is the tip speed divided by the shear gap
width (minimal clearance between the rotor and stator). The shear
rate generated in a shear device may be in the greater than 20,000
s.sup.-1. In some embodiments the shear rate is at least 40,000
s.sup.-1. In some embodiments the shear rate is at least 100,000
s.sup.-1. In some embodiments the shear rate is at least 500,000
s.sup.-1. In some embodiments the shear rate is at least 1,000,000
s.sup.-1. In some embodiments the shear rate is at least 1,600,000
s.sup.-1. In embodiments, the shear rate generated by a shear
device is in the range of from 20,000 s.sup.-1 to 100,000 s.sup.-1.
For example, in one application the rotor tip speed is about 40 m/s
(7900 ft/min) and the shear gap width is 0.0254 mm (0.001 inch),
producing a shear rate of 1,600,000 s.sup.-1. In another
application the rotor tip speed is about 22.9 m/s (4500 ft/min) and
the shear gap width is 0.0254 mm (0.001 inch), producing a shear
rate of about 901,600 s.sup.-1. In some embodiments, shear device
comprises a colloid mill. Suitable colloidal mills are manufactured
by IKA.RTM. Works, Inc. Wilmington, N.C. and APV North America,
Inc. Wilmington, Mass., for example. In some instances, shear
device comprises the DISPAX REACTOR.RTM. of IKA.RTM. Works,
Inc.
[0031] The high shear device comprises at least one revolving
element that creates the mechanical force applied to the stream
that passes through. The high shear device comprises at least one
stator and at least one rotor separated by a clearance. For
example, the rotors may be conical or disk shaped and may be
separated from a complementarily-shaped stator. In embodiments,
both the rotor and stator comprise a plurality of
circumferentially-spaced teeth. In some embodiments, the stator(s)
are adjustable to obtain the desired shear gap between the rotor
and the stator of each generator (rotor/stator set). Grooves
between the teeth of the rotor and/or stator may alternate
direction in alternate stages for increased turbulence. Each
generator may be driven by any suitable drive system configured for
providing the necessary rotation.
[0032] In some embodiments, the minimum clearance (shear gap width)
between the stator and the rotor is in the range of from about
0.0254 mm (0.001 inch) to about 3.175 mm (0.125 inch). In certain
embodiments, the minimum clearance (shear gap width) between the
stator and rotor is about 1.52 mm (0.060 inch). In certain
configurations, the minimum clearance (shear gap) between the rotor
and stator is at least 1.78 mm (0.07 inch). The shear rate produced
by the high shear device may vary with longitudinal position along
the flow pathway. In some embodiments, the rotor is set to rotate
at a speed commensurate with the diameter of the rotor and the
desired tip speed. In some embodiments, the high shear device has a
fixed clearance (shear gap width) between the stator and rotor.
Alternatively, the high shear device has adjustable clearance
(shear gap width).
[0033] In some embodiments, a shear device comprises a single stage
dispersing chamber (i.e., a single rotor/stator combination, a
single generator). In some embodiments, a shear device is a
multiple stage inline disperser and comprises a plurality of
generators. In certain embodiments, a shear device comprises at
least two generators. In other embodiments, a shear device
comprises at least 3 high shear generators. In some embodiments, a
shear device is a multistage mixer whereby the shear rate (which,
as mentioned above, varies proportionately with tip speed and
inversely with rotor/stator gap width) varies with longitudinal
position along the flow pathway, as further described herein
below.
[0034] In some embodiments, each stage of the shear device has
interchangeable mixing tools, offering flexibility. For example,
the DR 2000/4 DISPAX REACTOR.RTM. of IKA.RTM. Works, Inc.
Wilmington, N.C. and APV North America, Inc. Wilmington, Mass.,
comprises a three stage dispersing module. This module may comprise
up to three rotor/stator combinations (generators), with choice of
fine, medium, coarse, and super-fine for each stage. This allows
for creation of dispersions having a narrow distribution of the
desired bubble size and particle size. In some embodiments, each of
the stages is operated with super-fine generator. In some
embodiments, at least one of the generator sets has a rotor/stator
minimum clearance (shear gap width) of greater than about 5.0 mm
(0.20 inch). In alternative embodiments, at least one of the
generator sets has a minimum rotor/stator clearance of greater than
about 1.78 mm (0.07 inch).
[0035] FIG. 1A presents a longitudinal cross-section of a suitable
shear device 200. Shear device 200 of FIG. 1A is a dispersing
device comprising a combination 220 of a rotor 222 and a stator
227. The rotor-stator combination may be known as generator 220 or
stage without limitation. The rotor 222 and stator 227 are fitted
along drive shaft 250.
[0036] For generator 220, the rotor 222 is rotatably driven by
input 250 and rotates about axis 260 as indicated by arrow 265. The
direction of rotation may be opposite that shown by arrow 265
(e.g., clockwise or counterclockwise about axis of rotation 260).
Stator 227 is fixably coupled to the wall 255 of shear device 200.
Generator 220 has a shear gap width which is the minimum distance
between the rotor and the stator. In the embodiment of FIG. 1A,
generator 220 comprises a shear gap 225.
[0037] Generator 220 may comprise a coarse, medium, fine, and
super-fine characterization. Rotors 222 and stators 227 may be
toothed designs. Generator 220 may comprise two or more sets of
rotor-stator teeth. In embodiments, rotor 222 comprises rotor teeth
circumferentially spaced about the circumference of the rotor. In
embodiments, stator 227 comprises stator teeth circumferentially
spaced about the circumference of the stator.
[0038] Shear device 200 is configured for receiving fluid mixtures
at inlet 205. Fluid mixtures entering inlet 205 are pumped serially
through generator 220, such that product dispersions are formed.
Product dispersions exit shear device 200 via outlet 210. Rotor 222
of generator 220 rotates at a speed relative to the fixed stator
227, providing adjustable shear rates. The rotation of the rotor
pumps fluid, such as the fluid mixtures entering inlet 205,
outwardly through the shear gaps (and, if present, through the
spaces between the rotor teeth and the spaces between the stator
teeth), creating a localized shear condition. Shear forces exerted
on fluid in shear gap 225 (and, when present, in the gaps between
the rotor teeth and the stator teeth) through which fluid flows
process the fluid and create product dispersion. Product dispersion
exits shear device 200 via shear outlet 210.
[0039] In certain instances, shear device 200 comprises a
ULTRA-TURRAX.RTM. of IKA.RTM. Works, Inc. Wilmington, N.C. Several
models are available having variable sizes, volume capacities, flow
rates, tip speeds, inlet/outlet connections, horsepower, output
rpm, and operable temperature ranges. For example, the T 10 basic
ULTRA-TURRAX.RTM. homogenizer provides a stepless control of speed
with a speed range of 8000-30000 min.sup.-1 and adjustable
dispersing elements.
[0040] In certain embodiments, more than one stage or combination
of rotor and stator may be employed. For example, two or three
stages of rotor-stator combinations may be connected serially along
the same drive shaft to enable flexibility to provide variable
shear stress. Fluid mixtures are passed through different stages of
rotor-stator combinations to be processed serially until the
desired dispersion products are formed. Examples of adjustable
operational parameters are rotor size, stator size, shear gap,
rotor speed, tip speed, shear rate, flow rate, and residence
time.
[0041] FIG. 1B presents a longitudinal cross-section of a
three-stage shear device 200, comprising three stages or
rotor-stator combinations 220, 230, and 240 as a dispersing device.
The rotor-stator combinations may be known as generators 220, 230,
240 or stages without limitation. Three rotor/stator sets or
generators 220, 230, and 240 are aligned in series along drive
shaft 250.
[0042] First generator 220 comprises rotor 222 and stator 227.
Second generator 230 comprises rotor 223, and stator 228. Third
generator 240 comprises rotor 224 and stator 229. For each
generator the rotor is rotatably driven by input 250 and rotates
about axis 260 as indicated by arrow 265. The direction of rotation
may be opposite that shown by arrow 265 (e.g., clockwise or
counterclockwise about axis of rotation 260). Stators 227, 228, and
229 are fixably coupled to the wall 255 of high shear device
200.
[0043] As mentioned hereinabove, each generator has a shear gap
width which is the minimum distance between the rotor and the
stator. In the embodiment of FIG. 1B, first generator 220 comprises
a first shear gap 225; second generator 230 comprises a second
shear gap 235; and third generator 240 comprises a third shear gap
245. In embodiments, shear gaps 225, 235, 245 have widths in the
range of from about 0.025 mm to about 10.0 mm. Alternatively, the
process comprises utilization of a high shear device 200 wherein
the gaps 225, 235, 245 have a width in the range of from about 0.5
mm to about 2.5 mm. In certain instances the shear gap width is
maintained at about 1.5 mm. Alternatively, the width of shear gaps
225, 235, 245 are different for generators 220, 230, 240. In
certain instances, the width of shear gap 225 of first generator
220 is greater than the width of shear gap 235 of second generator
230, which is in turn greater than the width of shear gap 245 of
third generator 240. As mentioned above, the generators of each
stage may be interchangeable, offering flexibility. High shear
device 200 may be configured so that the shear rate will increase
stepwise longitudinally along the direction of the flow 260.
[0044] Generators 220, 230, and 240 may comprise a coarse, medium,
fine, and super-fine characterization. Rotors 222, 223, and 224 and
stators 227, 228, and 229 may be toothed designs. Each generator
may comprise two or more sets of rotor-stator teeth. In
embodiments, rotors 222, 223, and 224 comprise more than 10 rotor
teeth circumferentially spaced about the circumference of each
rotor. In embodiments, stators 227, 228, and 229 comprise more than
ten stator teeth circumferentially spaced about the circumference
of each stator. In embodiments, the inner diameter of the rotor is
about 12 cm. In embodiments, the diameter of the rotor is about 6
cm. In embodiments, the outer diameter of the stator is about 15
cm. In embodiments, the diameter of the stator is about 6.4 cm. In
some embodiments the rotors are 60 mm and the stators are 64 mm in
diameter, providing a clearance of about 4 mm. In certain
embodiments, each of three stages is operated with a super-fine
generator, comprising a shear gap of between about 0.025 mm and
about 4 mm. For applications in which solid particles are to be
sent through high shear device 40, the appropriate shear gap width
(minimum clearance between rotor and stator) may be selected for an
appropriate reduction in particle size and increase in particle
surface area. In embodiments, this may be beneficial for increasing
surface area of solid drugs by shearing and dispersing the
particles.
[0045] High shear device 200 is configured for receiving a feed
stream at inlet 205. Feed stream entering inlet 205 is pumped
serially through generators 220, 230, and then 240, such that a
dispersion is formed. The dispersion exits high shear device 200
via outlet 210. The rotors 222, 223, 224 of each generator rotate
at high speed relative to the fixed stators 227, 228, 229,
providing a high shear rate. The rotation of the rotors pumps
fluid, such as the feed stream entering inlet 205, outwardly
through the shear gaps (and, if present, through the spaces between
the rotor teeth and the spaces between the stator teeth), creating
a localized high shear condition. High shear forces exerted on
fluid in shear gaps 225, 235, and 245 (and, when present, in the
gaps between the rotor teeth and the stator teeth) through which
fluid flows process the fluid and create the dispersion. The
product dispersion exits high shear device 200 via high shear
outlet 210.
[0046] The produced dispersion has an average gas bubble size less
than about 5 .mu.m. In embodiments, shear device 200 produces a
dispersion having a mean bubble size of less than about 1.5 .mu.m.
In embodiments, shear device 200 produces a dispersion having a
mean bubble size of less than 1 .mu.m; preferably the bubbles are
sub-micron in diameter. In certain instances, the average bubble
size is from about 0.1 .mu.m to about 1.0 .mu.m. In embodiments,
shear device 200 produces a dispersion having a mean bubble size of
less than 400 nm. In embodiments, shear device 200 produces a
dispersion having a mean bubble size of less than 100 nm. Shear
device 200 produces a dispersion comprising dispersed gas bubbles
capable of remaining dispersed at atmospheric pressure for at least
about 15 minutes.
[0047] In certain instances, high shear device 200 comprises a
DISPAX REACTOR.RTM. of IKA.RTM. Works, Inc. Wilmington, N.C. and
APV North America, Inc. Wilmington, Mass. Several models are
available having various inlet/outlet connections, horsepower, tip
speeds, output rpm, and flow rate. Selection of the high shear
device will depend on throughput requirements and desired particle
or bubble size in dispersion exiting outlet 210 of high shear
device 200. IKA.RTM. model DR 2000/4, for example, comprises a belt
drive, 4M generator, PTFE sealing ring, inlet flange 25.4 mm (1
inch) sanitary clamp, outlet flange 19 mm (3/4 inch) sanitary
clamp, 2HP power, output speed of 7900 rpm, flow capacity (water)
approximately 300-700 L/h (depending on generator), a tip speed of
from 9.4-41 m/s (1850 ft/min to 8070 ft/min).
Application of Shear in Drug Delivery
[0048] In an embodiment, the application of shear comprises passing
a drug-containing therapeutic fluid through a shear device as
described herein, wherein said drug is processed into its nano-size
equivalent, as illustrated by FIG. 2A. As used herein, "nano-size"
refers to the size range of sub-nanometers to 1000 nanometers. In
an embodiment, the application of shear comprises passing a
drug-containing therapeutic fluid and a drug carrier through a
shear device, wherein the drug carrier is loaded with the drug
after the shearing process, as illustrated by FIG. 3A. In an
embodiment, the application of shear comprises passing a
drug-containing therapeutic fluid and a drug carrier through a
shear device, wherein the drug carrier is loaded with the drug; and
modifying the drug-loaded carrier; as illustrated by FIG. 4A. In
various embodiments, fluid passage is sterilized and is maintained
sterile.
Nano-Size Drugs
[0049] In an embodiment, as illustrated by FIG. 2A, a therapeutic
fluid containing a drug is processed by a shear device. The drug
contained therein is subjected to a suitable shear rate for a
period of time so that the processed therapeutic fluid after
exiting the shear device contains the nano-size equivalent of the
drug.
[0050] The shear rate generated in high shear device (HSD) may be
in the greater than 20,000 s.sup.-1. In some embodiments the shear
rate is at least 40,000 s.sup.-1. In some embodiments the shear
rate is at least 100,000 s.sup.-1. In some embodiments the shear
rate is at least 500,000 s.sup.-1. In some embodiments the shear
rate is at least 1,000,000 s.sup.-1. In some embodiments the shear
rate is at least 1,600,000 s.sup.-1. In embodiments, the shear rate
generated by HSD is in the range of from 20,000 s.sup.-1 to 100,000
s.sup.-1. For example, in one application the rotor tip speed is
about 40 m/s (7900 ft/min) and the shear gap width is 0.0254 mm
(0.001 inch), producing a shear rate of 1,600,000 s.sup.-1. In
another application the rotor tip speed is about 22.9 m/s (4500
ft/min) and the shear gap width is 0.0254 mm (0.001 inch),
producing a shear rate of about 901,600 s.sup.-1.
[0051] In some embodiments, the processed therapeutic fluid is
immediately administered to a patient via any suitable means known
to one skilled in the art. In some other embodiments, the processed
therapeutic fluid is stored. In some further embodiments, the
processed therapeutic fluid is further processed.
[0052] Selection of the shear device, shear rate, shear stress, and
residence time applied in shear device depends on the amount of
therapeutic fluid/dispersion administered and the nature of the
components of the therapeutic fluids utilized. The operational
parameters are further adjusted according to the objectives of
tasks at hand, which dictate the specific requirements for the
therapeutic fluids. For example, the dispersion of gases and
liquids in a continuous phase may take place at a lower rate and/or
for a shorter time than in the case of the dispersion of
solids.
[0053] In some embodiments, shear is applied to therapeutic fluids
to treat diseases such as cancers and brain diseases. In
alternative embodiments, shear is applied to therapeutic fluids to
treat diseases according to one's interest and the use of available
drugs.
[0054] Referring to FIG. 2B, a therapeutic fluid 5 containing a
drug is transported and stored in a vessel 20 with a temperature
control unit 30. Alternatively, the creation of therapeutic fluid 5
is achieved by any other suitable method known to one skilled in
the art. The temperature control unit 30 is any device known to one
skilled in the art and has the capacity to maintain a temperature
between 0-100.degree. C. within .+-.2.degree. C. fluctuations. In
some embodiments, a pump 10 is included to control the flow into
vessel 20. Pump 10 is configured for either continuous or
semi-continuous operation, and may be any suitable pumping device.
Vessel 20 is configured to be in fluid connection with shear device
40 (at inlet 205 in FIGS. 1A and 1B), wherein said fluid connection
may be any as known to one skilled in the art. The temperature of
shear device 40 is maintained by a temperature control unit 30,
wherein said temperature control unit 30 is any device known to one
skilled in the art and has the capacity to maintain a temperature
between 0-100.degree. C. within .+-.2.degree. C. fluctuations.
Shear device 40 is configured to be in fluid communication (at
outlet 210 in FIGS. 1A and 1B) with vessel 50, wherein said fluid
communication may be any as known to one skilled in the art. The
temperature of vessel 50 is maintained by a temperature control
unit 30, wherein said temperature control unit 30 is any device
known to one skilled in the art and has the capacity to maintain a
temperature between 0-100.degree. C. within .+-.2.degree. C.
fluctuations. In some embodiments, a pump 45 is included to control
the flow into vessel 50. Pump 45 is configured for either
continuous or semi-continuous operation, and may be any suitable
pumping device. In some cases, processed therapeutic fluid 55 is
administered to a patient via a catheter intravenously. The method
of administering processed therapeutic fluid 55 to a patient may be
any known to one skilled in the art, such as intravenous injection,
intravenous infusion, or intramuscular injection.
[0055] Advantages.
[0056] In some embodiments, the application of shear is especially
useful in creating therapeutic dispersions/fluids wherein the
therapeutic agents (drugs) are not miscible or soluble in the
continuous phase. For example, ozone as a therapeutic gas is
dispersed in phosphate buffer saline (PBS) into gas bubbles that
are on the nano or sub-nano scale. When such dispersions are
injected or infused into patients, ozone gas is circulated in the
bloodstream and transported to various organs and tissues. Because
the size of the produced gas bubbles are small (nano-,
sub-nano-size), ozone gas has the potential to overcome the blood
brain barrier (BBB) to obtain access to the brain and therefore
become effective therapeutically.
[0057] Many other kinds of drugs have low solubility in aqueous
solution in the range of room temperature and body temperature. In
the same principle as the ozone therapy example, the application of
shear stress can create dispersions of such therapeutics, make them
administrable to patients, and increase their therapeutic efficacy.
Some examples are but not limited to anti-inflammatory drugs (e.g.,
ibuprofen, acetaminophen), anti-cancer drugs (doxorubicin,
paclitaxel, 5-fluorouracil), and anti-HIV drugs (e.g.,
azodicarbonamide). When drugs are dispersed in fluids to nano- and
sub-nano-sizes, they can escape being captured by the
reticuloendothelial system (RES) and reach the target drug action
site via blood circulation.
[0058] The fine dispersion of the drug combined with passage
through the shear device allows for better absorption of drugs into
the cells and tissues, thus making the drugs more effective and
reducing adverse effects the drugs have on the liver. This also
reduces the amount of drugs required because the liver is not
filtering out the drugs. In some cases, the application of shear
activates chemotherapy drugs by creating free radicals. These
radicals are capable of destroying cancer cells. Thus the
application of shear increases the efficacy of the chemotherapy
drugs.
[0059] In an embodiment, applying shear to a drug-containing
therapeutic fluid causes a non-administrable drug to become
available for administration (such as hydrophobic drugs,
therapeutic gases) because such drugs become well-dispersed in and
intimately-mixed with the fluid in their nano-size equivalents
after being subjected to shear processing. In an embodiment,
applying shear to a drug-containing therapeutic fluid increases the
bioavailability of the drug. In another embodiment, applying shear
to a drug-containing therapeutic fluid changes the pharmacokinetics
and/or pharmacodynamics of the drug. For example, drug absorption,
distribution, and/or elimination are changed to improve drug
efficacy and safety.
Drug-Loaded Carriers
[0060] In an embodiment, as illustrated by FIG. 3A, a therapeutic
fluid containing a drug is processed in a shear device together
with a drug carrier. The drug and the drug carrier are subjected to
a suitable shear rate for a period of time so that the processed
therapeutic fluid after exiting the shear device contains the
carrier loaded/incorporated with the drug. The
loading/incorporation of the drug into the drug carrier may be via
any suitable mechanism (such as chemical or physical bonding,
absorption) depending on the type of the drug and the carrier.
[0061] The shear rate generated in high shear device (HSD) may be
in the greater than 20,000 s.sup.-1. In some embodiments the shear
rate is at least 40,000 s.sup.-1. In some embodiments the shear
rate is at least 100,000 s.sup.-1. In some embodiments the shear
rate is at least 500,000 s.sup.-1. In some embodiments the shear
rate is at least 1,000,000 s.sup.-1. In some embodiments the shear
rate is at least 1,600,000 s.sup.-1. In embodiments, the shear rate
generated by HSD is in the range of from 20,000 s.sup.-1 to 100,000
s.sup.-1. For example, in one application the rotor tip speed is
about 40 m/s (7900 ft/min) and the shear gap width is 0.0254 mm
(0.001 inch), producing a shear rate of 1,600,000 s.sup.-1. In
another application the rotor tip speed is about 22.9 m/s (4500
ft/min) and the shear gap width is 0.0254 mm (0.001 inch),
producing a shear rate of about 901,600 s.sup.-1.
[0062] In some embodiments, the processed therapeutic fluid is
immediately administered to a patient via any suitable means known
to one skilled in the art. In some other embodiments, the processed
therapeutic fluid is stored. In some further embodiments, the
processed therapeutic fluid is further processed.
[0063] Selection of the shear device, shear rate, shear stress, and
residence time applied in shear device also depends on the amount
of therapeutic fluid/dispersion, the type and amount of drug, the
type and amount of drug carrier utilized.
Drug Carrier
[0064] Drug carriers are often used to (1) increase the drug
bioavailability at target site; (2) reduce the toxic side effects
of drugs for normal tissues; (3) reduce drug degradation before it
reaches the desired site of action. Drug carriers (or drug delivery
systems/vehicles) are designed to achieve the above effects by (1)
encapsulating drugs inside and thus providing them protection
before they reach the desired site of action; (2) changing the size
and molecular weight of the "effective drugs" and thus optimizing
their biodistribution and pharmacokinetics; and (3) utilizing
various targeting schemes and thus minimizing the side effects to
normal/healthy tissues. For example, hydrophobic drugs, which are
not soluble in the blood and do not reach their target site, can
thereby be administered via the use of a suitable carrier. Such
suitable carriers include small molecules, proteins, and large DNA
fragments.
[0065] Generally speaking, drug carriers comprise polymer-based
systems, liposomes and lipid nanoparticles, viral vectors and
virus-like particles, nanofibers, and inorganic nanoparticles with
sizes ranging from nanometers to microns.
Polymer-Based Systems
[0066] Polymeric Nanoparticles.
[0067] Polymers offer great flexibility as delivery systems in
terms of their synthesis and preparation methods, types of agents
that can be encapsulated, and their versatility (e.g.,
biocompatibility, biodegradability, surface modifiability). Some
natural polymers that have been used to construct delivery systems
are: albumin, gelatin, alginate, collagen, and chitosan. A few
examples of synthetic polymers are: poly lactic acid (PLA), poly
glycolic acid (PGA), their copolymers poly lactide-co-glycolide
(PLGA), polyacrylates, poly caprolactone (PCL), and polyethylene
oxide (PEO). The methods used to prepare polymeric nanoparticles
include single (oil-in-water) emulsion, double
(water-in-oil-in-water) emulsion, emulsification solvent diffusion
method, self-assembly, etc. The drug release profile from the
polymeric nanoparticles can be modulated by polymer/drug properties
and external conditions, such as pH, temperature, and magnetic
field.
[0068] A classic representation of polymeric nanoparticles as
versatile delivery systems can be seen in the case of polymeric
micelles. Micelle core formation can be driven by different forces
(e.g., hydrophobic interactions, electrostatic interactions);
micelle shell often serves for biocompatibility and steric
stabilization; the surface of the micelles can be modified to
include targeting moieties, (e.g., peptides, antibodies). The wide
variety of tunable parameters of polymeric nanoparticles has
enabled them to be used as delivery systems in numerous biomedical
applications. A few of the most important applications are cancer
chemotherapy, drug delivery to the brain, and gene delivery.
[0069] Dendrimers.
[0070] Dendrimers are highly branched macromolecules with repeated
units. The first dendrimers were synthesized by Vogtle in 1978 with
"a divergent method", followed by others such as Tomalia. In 1990
Frechet introduced the "convergent" approach to synthesize
well-defined dendritic molecular architectures. Since then,
dendrimers have drawn tremendous attention due to their unique
molecular architecture. Some of their outstanding features are: (1)
highly branched structures giving rise to multivalency, (2)
well-defined molecular weight with low polydispersity index, (3)
tunable core structure and folding branches creating cavities of
hydrophilic or hydrophobic nature, and (4) surface groups amenable
for modification for desired applications. As a result, delivery
systems formed by dendrimers have well-controlled size, shape,
density, polarity, reactivity, and solubility. Bioactive agents can
be incorporated by being encapsulated into the dendrimer core or
chemically attached or physically adsorbed onto the dendrimer
surface.
[0071] Among more than 50 families of dendrimers, poly amidoamine
(PAMAM) dendrimers are the first that are synthesized,
characterized, and commercialized. PAMAM has been utilized to
incorporate and to deliver genes, anti-tumor drugs (e.g.,
5-fluorouracil), anti-inflammatory drugs (e.g., ketoprofen), and
antimalarial drugs (e.g., artemether).
[0072] Nanogels.
[0073] Nanogels are networks of polymeric particles formed by
cross-linking, whose size is in the submicron range. Nanogels can
be prepared by two different methods: (1) emulsion polymerization;
and (2) cross-linking of preformed polymer fragments. Emulsion
polymerization is the most commonly used method for nanogel
preparation, but because the polymerization takes place in a
mixture (usually an emulsion) of monomers, cross-linking agents,
and surfactants, the final products are often toxic and not
suitable for biomedical applications unless purified after the
synthesis.
[0074] The advantages of using nanogels as drug delivery systems
are their high drug loading capacity and their ability to respond
reversibly to change in external conditions, e.g., temperature, pH,
ionic strength, and solvent property. Temperature-responsive
nanogels are mostly constructed by poly N-isopropylacrylamide
(PNIPAAm) and its derivatives. The mechanism is based on polymer
phase separation phenomenon that occurs when the temperature is
raised to its lower critical solution temperature (LCST), above
which nanogels tend to shrink/collapse and below which they are
swollen. These nanogels have manifested controlled and sustained
release of drug when subject to temperature changes.
[0075] PH-sensitive nanogels made of poly methacrylic
acid-grafted-ethylene glycol [P(MAA-g-EG)] have been used for
protein delivery. Insulin has been incorporated into P(MAA-g-EG)
nanogels and tested via oral administration. In an acidic
environment, such as that of the stomach, the gels are not swollen
because of the formation of intermolecular complexes, protecting
insulin from degradation by proteases. In basic and neutral
environments, such as that of the intestine, the intermolecular
complexes dissociate, causing rapid gel swelling and consequent
insulin release. Other examples include glucose-sensitive nanogels,
gene delivery, and anti-tumor drug delivery.
Liposomes and Lipid Nanoparticles
[0076] Liposomes and lipid nanoparticles are spherical vesicles,
whose membranes are composed of phospholipid bilayer. They can be
made by different methods, e.g., extrusion, reversed-phase
evaporation, detergent-based procedures, high pressure
homogenization, micro-emulsion method, high speed stirring and/or
ultrasonication, water-oil-water double emulsion method, solvent
emulsification evaporation/diffusion.
[0077] Liposomes are another type of drug carriers. There are four
mechanisms of liposome-cell interactions: (1) adsorption, (2)
endocytosis, (3) fusion, and (4) lipid exchange. Liposomes have
great flexibility with regard to their size, structure,
composition, and modification. Bioactive agents can be encapsulated
in the aqueous environment of the lipid bilayer vesicle (e.g.,
hydrophilic drugs and DNA). Lipid-soluble drugs can be solubilized
in the lipid bilayer. Surface modifications can prevent them from
being captured by the reticuloendothelial system (RES). Homing
peptides can help them to actively target pathological tissues for
diagnosis and treatment of diseases. Unmodified liposomes are
preferentially taken up by the RES; therefore they have been used
to encapsulate drugs with toxic side effects and to passively
target the RES. An example is the use of antibiotic amphotericin B
to treat systemic fungal infections. Amphotericin B has extensive
renal toxicity; whereas liposomal amphotericin B (Ambisome) reduces
the renal toxicity of the drug at normal doses while treating the
liver and spleen by passive targeting. Other applications include
using liposomes to enhance immunological response
(immunoadjuvants), to deliver genes into specific cells in the
body, and to deliver active agents to brain.
Viral Vectors and Virus-Like Particles
[0078] Another category of delivery systems is viral vectors and
virus-like particles, which are designed to mimic viral behavior in
infecting cells. Viruses are very efficient in transfecting their
own DNA into specific host cells and use the machinery of the host
cells to reproduce themselves. This behavior is ideal in drug or
gene delivery, but because viruses are pathogenic, they must be
used in modified forms. Recombinant viral vectors and virus-like
particles (VLPs) are such modified delivery systems.
[0079] Recombinant Viral Vectors.
[0080] A recombinant viral vector is designed to retain the
efficiency of gene transfer and expression but to eliminate the
pathogenicity of the virus. The nonessential genes of the viruses
(for their replication phase) are replaced by foreign genes of
interest so as to disable the innate viral infection in the host.
But the modified viruses are still capable of transfecting the
desired cell types with the foreign genes of interest and induce
gene expression in the host.
[0081] There are many different types of recombinant viral vectors,
e.g., adenovirus vectors, retrovirus vectors, adeno associated
virus vectors, vaccinia virus vectors, herpes simplex virus
vectors, etc. Adenovirus vectors contain linear double-stranded
DNA's with no envelopes. They can be produced cost-effectively and
consistently with high infectious ability into both dividing and
non-dividing cells. Though they are widely used for gene delivery
in vivo and are in clinical trials for cancer therapy, they often
stimulate immune response to the cells transfected and thus cause
loss of gene expression 1-2 weeks after injection.
[0082] Retrovirus vectors are modified from retroviruses that have
single-stranded RNA's and envelopes, which contain proteins that
specifically interact with surface receptors of the target cells.
The viral replication genes are replaced with foreign genes of
interest. After cell infection, the viral genome is reverse
transcribed into double-stranded DNA, integrated into the host
genome, and expressed as proteins. Two major advantages of using
retroviral vectors in gene delivery are (1) stable long-term
integration in the host genome and (2) lowest clinical toxicity.
Therefore, they are most suitable for treatment of genetic diseases
where permanent gene expression is desirable.
[0083] Virus-Like Particles (VLPs).
[0084] Unlike recombinant viral vectors, virus-like particles
(VLPs) contain no viral genome at all but only the viral capsid
proteins so as to mimic the structural confirmation of the actual
viruses, which enables them to efficiently transfect cells.
[0085] Papilloma VLPs have been used for immune therapy for
papillomavirus-related diseases. For example, long-term protection
against the rabbit papilloma virus has been stimulated by the
papilloma VLPs. In addition, different types of papilloma VLPs have
been shown to induce immune responses from B and T lymphocytes and
thus demonstrated the potential of using VLPs for immunization
against different types of papillomaviruses. Another major category
of VLPs is polyomavirus-like particles. By encapsulating plasmid
pCMV-.beta.-gal as its genomic information, this system has
successfully transfected monkey kidney cell lines and caused
consequent expression of functional .beta.-galactosidase.
Furthermore, a fluorescent protein and a low molecular weight drug
methotrexate have been encapsulated by the polyoma VLPs and
delivered into mouse fibroblasts in vitro, giving promise to their
applications in not only gene delivery but also delivery of
therapeutics and vaccines.
Nanofibers
[0086] Nanofibers can be made from carbon, organometallic
compounds, inorganic compounds, and polymers. They have a diameter
of a few to hundreds of nanometers. Because of the
biocompatibility, biodegradability, and ease of formation,
polymeric nanofibers are suitable for biomedical applications. As
delivery systems, nanofibers have a few outstanding
characteristics: (1) large surface area, (2) ease of surface
functionalization, and (3) controlled pore size enabling modifiable
release kinetics by changing the composition and morphology of the
nanofibers. Different methods can be used to produce polymer
nanofibers, e.g., drawing, template synthesis, self-assembly, and
electrospinning, among which electrospinning is the most attractive
method for biomedical applications with the capability of
large-scale production.
[0087] Nano-fibrous scaffolds containing various growth factors are
useful in tissue engineering and have demonstrated controlled
release of the growth factors. These results hold promise for bone
repair and regeneration and for treating Alzheimer's disease and
Parkinson's disease, where peripheral nerve regeneration is needed.
Other applications of polymeric nanofibers include the delivery of
DNA and small drug molecules (e.g., antibiotic tetracycline
hydrochloride, anti-tuberculosis drug rifampin).
Inorganic Nanoparticles
[0088] Various inorganic nanoparticles have drawn significant
attention in biomedical applications due to their unique
structural, spectroscopic, or magnetic properties. They have
expanded the armory of nanotechnology as novel diagnostics and
therapeutics. Some examples of inorganic nanoparticle types are:
(1) carbon nanotubes and fullerenes, (2) quantum dots, (3)
nanoshells, (4) gold nanoparticles, and (5) paramagnetic
nanoparticles.
[0089] Carbon Nanotubes and Fullerenes.
[0090] The backbone of carbon nanotubes (CNTs) is composed only of
carbon atoms, which are arranged in benzene-ring conformation as
graphite sheets. The carbon graphite sheets are then rolled up to
form seamless cylinders, which can be either single-walled CNTs or
multi-walled CNTs. They are considered to be one of the allotropes
of carbon. The structure of fullerenes resembles that of a soccer
ball. Their diameter can be as small as 2 nm.
[0091] Carbon nanotubes can be produced by three different methods:
chemical vapor deposition, electric arc discharge, and laser
ablation. After the CNTs are produced, a significant amount of
residues are left in the final product. Therefore, purification is
necessary for subsequent applications. Various purification
techniques include oxidation, chromatography, centrifugation,
filtration, and chemical functionalization. Furthermore, because
CNTs are completely insoluble in aqueous solutions by themselves,
they need to be functionalized in order to be dispersed and
stabilized in solution for biomedical applications. Two approaches
have been used to modify the CNT surface to increase its
solubility--noncovalent and covalent. Suitable noncovalent
modifications include the use of polysaccharides, peptides,
proteins, and nucleic acids. Covalent modifications include (1) the
use of acids to add hydrophilic functional groups to the CNT
surface by oxidation and (2) the addition reaction that CNTs
undergo to become functionalized CNTs (f-CNTs), which are soluble
in various solvents. Functionalized CNTs (f-CNTs) have a few
attractive features for biomedical applications: (1) they have
large inner volume relative to the tube dimensions, which can be
loaded with desired bioactive agents for delivery; they have low
toxicity, and (3) they are non-immunogenic. For example, CNTs have
been double functionalized with fluorescein and an antibiotic drug
(amphotericin B, AmB), which enabled both the tracking of the
uptake of CNTs and the delivery of AmB as an antifungal treatment.
Other application of CNTs include the delivery of nucleic acids,
proteins, and vaccines.
[0092] Similar to CNTs, fullerenes can also be functionalized on
the surface to become soluble in aqueous solutions. Their hollow
structures allow loading of bioactive agents for drug and gene
delivery applications. Fullerenes are themselves strong
antioxidants. They are capable of removing free radicals that are
associated with certain diseases. For example, in neurodegenerative
diseases, oxygen free radicals break chemical bonds in critical
molecules (e.g., nucleic acids) due to the presence of their
unpaired electrons and thus cause cell damage and possible
apoptosis. Dugan et al. showed that carboxylic acid functionalized
fullerenes are water soluble and can efficiently scavenge free
radicals, which demonstrated their potential in treating
neurodegenerative diseases. In the case of cancer treatment,
intracellular uptake of fullerene-pyropheophorbide a complexes in
Jurkat cells has been reported, in which photo-induced cytotoxicity
was observed in culture. Furthermore, fullerene-paclitaxel
conjugate was reported to have significant anticancer activity with
slow drug release kinetics. Ashcroft et al. synthesized and
characterized a water-soluble fullerene derivative that is
covalently attached to an antibody to recognize human tumor cell
antigen, which opened up the opportunity of using fullerenes as
active targeting delivery systems. Other applications of fullerene
derivatives include delivery of antibacterial agents, plasmid DNA,
nuclear medicine, and magnetic resonance imaging contrast
agents.
[0093] Quantum Dots.
[0094] Quantum dots (QDs) are nano-scale semiconductors with many
superior optical properties compared to conventional fluorescent
dyes. The emission fluorescent spectra of QDs are tunable by
changing the composition and size of the QDs. Their spectra have
narrow and discreet frequencies from ultraviolet to the infrared
range. QDs are very efficient in absorbing and emitting light,
making them sensitive light sensors and excellent light emitters.
QDs are found to be 10-20 times brighter than organic dyes. QDs are
also one order of magnitude more resistant to photobleaching than
their organic fluorescent dye counterparts. QDs exhibit
cytotoxicity both in vitro and in vivo, which hinders their
biomedical applications. But QDs may be modified on the surface
with hydrophilic polymers and biological ligands, e.g., antibodies,
peptides, oligonucleotides. Therefore, they have the potential to
be developed into probes with specific targeting capabilities.
[0095] Han et al. reported the use of well-controlled
different-sized QDs embedded in polymeric microbeads for multicolor
optical coding in vitro, which can be used for gene expression
study, high-throughput screening, and medical diagnostics.
Furthermore, Gao et al. encapsulated semiconductor QDs with an ABC
triblock copolymer and linked to a monoclonal antibody that
specifically target human prostate cancer cells. This QD-based
multifunctional probe demonstrated cancer targeting and imaging
abilities in live animals. Other applications of QDs include lung
imaging and human breast cancer imaging.
[0096] Nanoshells.
[0097] Similar to quantum dots, nanoshells also have tunable
optical properties with emission/absorption spectra expanding from
the ultraviolet to the infrared frequencies. They are constructed
with a dielectric core (usually silica) with a thin metal shell
(typically gold). Nanoshells have no heavy metal in their
composition and therefore are not toxic. But their sizes are bigger
than QDs, which is the major disadvantage for their biomedical
applications.
[0098] Nanoshells with polyethylene glycol (PEG) coating have been
used in vivo as long-circulating imaging contrast agent with
optical coherence tomography and photoacoustic tomography. More
interestingly, nanoshells have been designed to serve as
photo-absorbers, which can generate effective thermal energy in
photo-thermal ablation therapy. AUROSHELL.TM. (Nanospectra)
particles belong to this nanoshell therapeutic family. After these
nanoparticles are delivered to neoplastic tissues, a near-infrared
laser light is illuminated externally at the tumor site,
AUROSHELL.TM. then act as specific heat generators by absorbing the
light energy and converting it to heat, thus destroying the
cancerous tissues.
[0099] Gold nanoparticles. Gold nanoparticles are easy to fabricate
and they can strongly absorb and scatter light at desired
wavelengths. Gold nanoparticles are less toxic compared to quantum
dots and the metal gold is approved by FDA for some therapeutic
applications. Copland
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6X15-4DCDW84-8&-
_user=501045&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000022659&_v-
ersion=1
&_urlVersion=0&_userid=501045&md5=0b717e9baff31087268800c4ecb5bb8-
c-affl et al. conjugated gold nanoparticles to a monoclonal
antibody to target human breast cancer cells. The in vitro
experiments demonstrated efficient selective targeting and imaging
by optoacoustic tomography of human SK-BR-3 breast cancer cells in
a gelatin phantom that optically resembled breast tissue. The limit
of detection concentration at a depth of 6 cm was 109 nanoparticles
per ml. Paciotti et al. developed a gold nanoparticle based drug
delivery system that has attached PEG and recombinant human tumor
necrosis factor on its surface. In vivo animal tests showed that
these nanoparticles, after intravenous administration, rapidly
accumulated in colon carcinomas but not in the livers, spleens, or
healthy organs, indicating that the particles escaped the RES
system and had selective targeting ability. The system was further
developed to include paclitaxel as a multifunctional nano-scale
delivery platform. Gold nanoparticles are further used in
radiotherapy, vital reflectance imaging, and photo-thermal cancer
therapy.
[0100] Paramagnetic Nanoparticles.
[0101] Paramagnetic nanoparticles have been utilized alongside with
the fast advancement of MRI. MRI has 3D high spatial resolution as
its advantage but lower sensitivity compared to nuclear imaging.
The successes of utilizing MRI for diagnosis and therapy assessment
depend to a large extend on the contrast-to-noise ratio obtainable,
which necessitates the use of contrast agents, e.g.,
gadolinium-based conjugates, iron oxide nanoparticles. Iron oxide
nanoparticles have attracted much attention because of their
superparamagnetic property (i.e., high magnetic susceptibility)
that enables them to produce substantially high contrast.
[0102] Ultra-small superparamagnetic iron oxide (USPIO) has been
found to be small enough to migrate across the capillary wall via
vesicular transport and through inter-endothelial junctions [202].
There have been numerous applications of this class of
nanoparticles in conjunction with both passive and active targeting
strategies. In the case of passive targeting, USPIO has been used
for MRI of cardiovascular diseases, MRI of the lymphatic system and
associated cancers and metastases, MRI of arthritis, MRI of
transplanted pancreatic islets, etc. For active targeting, iron
oxide nanoparticles have been conjugated to different targeting
moieties (e.g., antibodies, peptides) to detect cancers,
atherosclerotic plaques where apoptosis takes place, and even in
combination with delivery of chemotherapeutic drugs. There also
have been several commercialized iron oxide nanoparticles for
cancer diagnosis, e.g., ferumoxtran-10, AMI-227, and COMBIDEX.RTM.
developed by Advanced Magnetics Inc., and SINEREM.TM. by
Laboratoire Guerbet.
[0103] Referring to FIG. 3B, a drug carrier 8 is mixed with a
therapeutic fluid 5 in vessel 9 with a temperature control unit 30.
The temperature control unit 30 is any device known to one skilled
in the art and has the capacity to maintain a temperature between
0-100.degree. C. within .+-.2.degree. C. fluctuations. In
alternative embodiments, mixing vessel 9 is omitted. Mixing vessel
9 is configured to be in fluid connection with vessel 20. In some
embodiments, the temperature of vessel 20 is maintained by a
temperature control unit 30. The temperature control unit 30 is any
device known to one skilled in the art and has the capacity to
maintain a temperature between 0-100.degree. C. within
.+-.2.degree. C. fluctuations.
[0104] In some embodiments, a pump 10 is included to control the
flow into vessel 20. Pump 10 is configured for either continuous or
semi-continuous operation, and may be any suitable pumping device.
Vessel 20 is configured to be in fluid connection with shear device
40 (at inlet 205 in FIGS. 1A and 1B), wherein said fluid connection
may be any as known to one skilled in the art. The temperature of
shear device 40 is maintained by a temperature control unit 30,
wherein said temperature control unit 30 is any device known to one
skilled in the art and has the capacity to maintain a temperature
between 0-100.degree. C. within .+-.2.degree. C. fluctuations.
Shear device 40 is configured to be in fluid connection (at outlet
210 in FIGS. 1A and 1B) with vessel 50, wherein said fluid
connection may be any as known to one skilled in the art. The
temperature of vessel 50 is maintained by a temperature control
unit 30, wherein said temperature control unit 30 is any device
known to one skilled in the art and has the capacity to maintain a
temperature between 0-100.degree. C. within .+-.2.degree. C.
fluctuations. In some embodiments, a pump 45 is included to control
the flow into vessel 50. Pump 45 is configured for either
continuous or semi-continuous operation, and may be any suitable
pumping device. In some cases, processed therapeutic fluid 60
containing drug-loaded carrier is administered to a patient. The
method of administering processed therapeutic fluid 60 may be any
known to one skilled in the art, such as intravenous injection.
[0105] Advantages.
[0106] In some embodiments, the application of shear in creating a
drug-loaded carrier fully utilizes the features of the drug
carrier, some of which are discussed above; it also improves the
loading capacity of the drug carrier, thus reducing the amount of
drug and carrier wasted. For example, the application of shear
reduces the size of the drug and causes it to be more efficiently
packaged within a suitable drug carrier. In some cases, the amount
of drug loaded into a drug carrier per weight of the carrier is
increased by the application of shear. In some other cases, a
suitable interaction is created between an otherwise non-loadable
drug and a drug carrier by utilizing shear, thus making the
drug-carrier incorporation possible. In yet other cases, the
interaction between the drug and the carrier is enhanced by the
application of shear, thus causing the drug to be incorporated into
the carrier more efficiently.
Drug-Loaded Carriers and Modification
[0107] In an embodiment, as illustrated by FIG. 4A, a therapeutic
fluid containing a drug is processed in a shear device together
with a drug carrier. The drug and the drug carrier are subjected to
a suitable shear rate for a period of time so that the processed
therapeutic fluid after exiting the shear device contains the
carrier loaded/incorporated with the drug. In some embodiments, the
processed therapeutic fluid containing the drug-loaded carrier is
concentrated. In some cases, the drug-loaded carrier is extracted
or purified from the processed therapeutic fluid. The drug-loaded
carrier is then further modified with a targeting moiety to
constitute targeted drug delivery.
[0108] In some embodiments, the modified drug-loaded carrier is
immediately administered to a patient via any suitable means known
to one skilled in the art. In some other embodiments, the modified
drug-loaded carrier is stored. In some further embodiments, the
modified drug-loaded carrier is further processed.
Targeting Moiety
[0109] The targeting moiety utilized to modify (e.g., surface
modification) the drug-loaded carrier may be any known to one
skilled in the art. Some examples are antibodies, peptides,
polypeptides, nucleic acids, DNA, RNA, and their fragments. This
disclosure includes targeting moieties that are natural, isolated,
or synthetic. The targeting moieties may be used in multivalency or
single valency per drug carrier. The method for achieving carrier
modification is any suitable means known to one skilled in the
art.
[0110] Advantages.
[0111] In some embodiments, the application of shear in creating a
modified drug-loaded carrier fully utilizes the features of the
modified drug carrier; it also improves the loading capacity of the
drug carrier, thus reducing the amount of drug, carrier, and
targeting moiety wasted. For example, the application of shear
reduces the size of the drug and causes it to be more efficiently
packaged within a suitable drug carrier. In some cases, the amount
of drug loaded into a drug carrier per weight of the carrier is
increased by the application of shear. In some other cases, a
suitable interaction is created between an otherwise non-loadable
drug and a drug carrier by utilizing shear, thus making the
drug-carrier incorporation possible. In yet other cases, the
interaction between the drug and the carrier is enhanced by the
application of shear, thus causing the drug to be incorporated into
the carrier more efficiently. In targeted delivery, especially for
cancer treatment, these advantages reduce the amount of drug a
patient needs, thus reducing potential side effects.
[0112] While preferred embodiments of the invention have been shown
and described, modifications thereof can be made by one skilled in
the art without departing from the spirit and teachings of the
invention. The embodiments described herein are some only, and are
not intended to be limiting. Many variations and modifications of
the invention disclosed herein are possible and are within the
scope of the invention. Where numerical ranges or limitations are
expressly stated, such express ranges or limitations should be
understood to include iterative ranges or limitations of like
magnitude falling within the expressly stated ranges or limitations
(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater
than 0.10 includes 0.11, 0.12, 0.13, and so forth). Use of the term
"optionally" with respect to any element of a claim is intended to
mean that the subject element is required, or alternatively, is not
required. Both alternatives are intended to be within the scope of
the claim. Use of broader terms such as comprises, includes,
having, etc. should be understood to provide support for narrower
terms such as consisting of, consisting essentially of, comprised
substantially of, and the like.
[0113] Accordingly, the scope of protection is not limited by the
description set out above but is only limited by the claims which
follow, that scope including all equivalents of the subject matter
of the claims. Each and every claim is incorporated into the
specification as an embodiment of the present invention. Thus, the
claims are a further description and are an addition to the
preferred embodiments of the present invention. The disclosures of
all patents, patent applications, and publications cited herein are
hereby incorporated by reference, to the extent they provide some,
procedural or other details supplementary to those set forth
herein.
* * * * *
References