U.S. patent application number 11/187790 was filed with the patent office on 2005-11-17 for formulation for inhalation.
This patent application is currently assigned to Quadrant Drug Delivery Limited. Invention is credited to Robinson, Stuart, Smith, Susan Stewart.
Application Number | 20050255051 11/187790 |
Document ID | / |
Family ID | 26792692 |
Filed Date | 2005-11-17 |
United States Patent
Application |
20050255051 |
Kind Code |
A1 |
Robinson, Stuart ; et
al. |
November 17, 2005 |
Formulation for inhalation
Abstract
Microparticles, obtainable by spray-drying a substantially pure
solution of a therapeutic agent, consist essentially of the agent
having its therapeutic activity when administered to the lung. In a
preferred embodiment the agent is insulin.
Inventors: |
Robinson, Stuart; (Nether
Broughton, GB) ; Smith, Susan Stewart; (Loughborough,
GB) |
Correspondence
Address: |
MORRISON & FOERSTER LLP
755 PAGE MILL RD
PALO ALTO
CA
94304-1018
US
|
Assignee: |
Quadrant Drug Delivery
Limited
Nottingham
GB
NG11 6JS
|
Family ID: |
26792692 |
Appl. No.: |
11/187790 |
Filed: |
July 22, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11187790 |
Jul 22, 2005 |
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10218448 |
Aug 12, 2002 |
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6926908 |
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10218448 |
Aug 12, 2002 |
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09342356 |
Jun 29, 1999 |
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6451349 |
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60097137 |
Aug 19, 1998 |
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Current U.S.
Class: |
424/46 ;
424/489 |
Current CPC
Class: |
A61K 38/063 20130101;
A61K 38/28 20130101; A61K 9/0073 20130101; A61K 38/4826 20130101;
A61K 9/1688 20130101 |
Class at
Publication: |
424/046 ;
424/489 |
International
Class: |
A61L 009/04; A61K
009/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 1998 |
GB |
9814172.4 |
Claims
We claim:
1. Microparticles, obtainable by spray-drying a substantially pure
solution of a therapeutic agent, wherein the microparticles consist
essentially only of the therapeutic agent having its therapeutic
activity when administered to the lung, and further wherein the
therapeutic agent is selected from the group consisting of insulin,
DNase and trypsin.
2. Microparticles according to claim 1, wherein the therapeutic
agent is non-crystalline/amorphous.
3. Microparticles according to claim 1, consisting essentially of
the agent and a salt formed in dissolution of the agent.
4. Microparticles according to claim 2, consisting essentially of
the agent and a salt formed in dissolution of the agent.
5. Microparticles according to claim 3, wherein the salt is formed
from an alkali and a mineral acid.
6. Microparticles according to claim 4, wherein the salt is formed
from an alkali and a mineral acid.
7. Microparticles according to claim 5, wherein the microparticles
comprise less than 4% salt by weight of total solids.
8. Microparticles according to claim 6, wherein the microparticles
comprise less than 4% salt by weight of total solids.
9. A closed container containing, at ambient humidity,
microparticles according to claim 1.
10. A closed container containing, at ambient humidity,
microparticles according to claim 2.
11. An inhaler device comprising microparticles according to claim
1.
12. An inhaler device comprising microparticles according to claim
2.
13. A process for the preparation of microparticles according to
claim 1, which comprise spray-drying a substantially pure solution
of the therapeutic agent.
14. A process according to claim 13, wherein the solution contains
more than 10 mg/ml of agent.
15. A process according to claim 14, wherein the solution contains
20 to 200 mg/ml agent.
16. A process according to claim 14, wherein the solution contains
50 to 100 mg/ml agent.
17. A process according to claim 13, wherein the solution contains
less than 4% salt.
18. A process according to claim 13, wherein the solution is free
of buffer salt.
19. A process according to claim 17, wherein the solution is free
of buffer salt.
20. An inhaler device comprising microparticles according to claim
3.
21. An inhaler device comprising microparticles according to claim
4.
22. An inhaler device comprising microparticles according to claim
5.
23. An inhaler device comprising microparticles according to claim
6.
24. An inhaler device comprising microparticles according to claim
7.
25. An inhaler device comprising microparticles according to claim
8.
26. A closed container containing, at ambient humidity,
microparticles according to claim 3.
27. A closed container containing, at ambient humidity,
microparticles according to claim 4.
28. A closed container containing, at ambient humidity,
microparticles according to claim 5.
29. A closed container containing, at ambient humidity,
microparticles according to claim 6.
30. A closed container containing, at ambient humidity,
microparticles according to claim 7.
31. A closed container containing, at ambient humidity,
microparticles according to claim 8.
32. A process for the preparation of microparticles according to
claim 2, which comprise spray-drying a substantially pure solution
of a therapeutic agent.
33. A process according to claim 32, wherein the solution contains
more than 10 mg/ml of agent.
34. A process according to claim 33, wherein the solution contains
20 to 200 mg/ml agent.
35. A process according to claim 33, wherein the solution contains
50 to 100 mg/ml agent.
36. A process according to claim 33, wherein the solution contains
less than 4% salt.
37. A process according to claim 33, wherein the solution is free
of buffer salt.
38. A process according to claim 36, wherein the solution is free
of buffer salt.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/218,448, filed Aug. 12, 2002, which is a continuation
of U.S. patent application Ser. No. 09/342,356, filed Jun. 29, 1999
and issued as U.S. Pat. No. 6,451,349, which claims priority to
U.S. Provisional Patent Application No. 60/097,137 filed Aug. 19,
1998, and Great Britain Patent Application No. 9814172.4 filed Jun.
30, 1998, the disclosures of each of which are incorporated herein
by reference in their entirety.
FIELD OF THE INVENTION
[0002] This invention relates to a formulation of a therapeutic
agent such as insulin, that is suitable for administration to the
lung, and that has good stability.
BACKGROUND OF THE INVENTION
[0003] There is now widespread interest in the formulation of
therapeutic agents for inhalation. In particular, many efforts have
been made to formulate suitable therapeutic agents as dry powders
for delivery via inhalers.
[0004] Typically, the formulations are produced by drying the
active agent in the presence of certain excipients, such as
polysaccharides or citrate, to enhance stability during the drying
process or in storage.
[0005] Insulin is a typical example of a therapeutic agent that can
be administered to the lung, by inhalation. As a commercial
product, insulin is generally provided in suspension or a solution
of low concentration, as a hexamer complexed with zinc.
Refrigeration is necessary, in order to maintain the stability of
such a formulation. Crystalline Zn insulin is stable at neutral pH.
The dry powder also requires refrigeration.
[0006] CA-A-2136704 discloses a product obtained by spray-drying a
medicinal substances such as insulin (among many others) and a
carrier. Example 4 discloses spray-drying a clear solution of human
insulin, soya bean lecithin and lactose.
[0007] WO-A-9735562 again discloses spray-drying a solution of
insulin and a polysaccharide. The aim of this combination is to
achieve the preferred size range of spray-dried microparticles, for
good lung deposition. In Examples 1 and 3, the insulin solution for
spray-drying, prior to combination with polysaccharide, is prepared
by dissolving zinc insulin in HCl, and then adding NaOH to pH 7.2.
The solutions for spray-drying respectively contain 25 and 6 mg/ml
insulin and at least 5.5/7.2% NaCl, based on the combined weight of
insulin plus salt.
[0008] WO-A-9524183 is directed primarily to a dry powder that
comprises insulin and a carrier material, typically a saccharide,
in the form of an amorphous powder of microparticles obtained by
spray-drying. In addition, the Experimental section compares the
properties of such microparticles with and without a saccharide
excipient. The insulin solution for spray-drying is prepared by
dissolving Zn-insulin in citrate buffer, to pH 6.7.+-.0.3, to a
solids content of 7.5 mg/ml. The powder is held in a container at
10% RH. The formulation without saccharide has considerably lower
bioavailability than those with saccharide. For various reasons,
this experiment cannot be reproduced: citrate is a buffer at pH
3.0-6.2, and not at pH 6.7; crystalline insulin will not dissolve
in pH 6.2 citrate buffer before or after adjustment to pH 7.4 with
NaOH; in any case, no alkali addition is specified.
[0009] The presence of citrate in dry powder formulations was
believed to be necessary to enhance the stability of the final
product (Drug Development and Industrial Pharmacy 1984;
10(3):425-451). However, in many cases, the high citrate
concentration dilutes the amount of active agent in the initial
feedstock, resulting in low amounts of active for drying.
[0010] After the date of this invention, Pikal and Rigsbee, Pharm.
Rev. 14(10):1379-87 (1997), reported that freeze-dried amorphous
insulin was significantly more stable than crystalline insulin at
corresponding water contents from 0 to 15% w/w. The mechanism was
unclear, but may have been due to configurational differences
between the amorphous and crystalline states, the reactive parts of
the protein being in closer proximity in the latter. The
formulation reported by Pikal and Rigsbee contains no salt, because
such low concentrations of insulin (c.0.5% w/v) are used that
manipulation of the pH is unnecessary.
[0011] WO95/23613 discloses a spray-dried DNase formulation. The
spray-dried product is in a crystalline form, due primarily to a
high concentration of salt. It is stated that high concentrations
of salt increases the dispersibility qualities of the final
product. In Example 1, the final product contains 60% salt compared
with 30% of the DNase.
[0012] In summary, the prior art discloses various results of
interest but of uncertain commercial significance. None of the
procedures described above gives a pure insulin product that is
stable,.or uses a sufficiently concentrated solution for
spray-drying, to be suitable as a commercial procedure. The most
effective procedures invariably suggest that co-spray-drying of
insulin and, say, a saccharide is necessary for best results.
SUMMARY OF THE INVENTION
[0013] The present invention is based on the surprising discovery
that it is possible to spray-dry a therapeutic agent at higher (and
therefore commercially useful) concentrations than have been used
previously, without the concomitant production of an undesirable
high concentration of salt or other excipients. Such formulations
show no substantial loss of activity after the drying process and
have extended stability, by comparison with pre-spray-dried
preparations. This discovery is of value for all therapeutic
agents, in particular proteins and peptides to be administered via
the lung.
[0014] According to the present invention, microparticles,
obtainable by spray-drying a substantially pure solution of a
therapeutic agent, consist essentially only of the agent. In a
preferred embodiment, the microparticles consist essentially only
of insulin and NaCl salt. Such microparticles may be held in a
container at greater than 10% RH, and thus essentially at ambient
humidity. The insulin microparticles are obtainable by dissolving
Zn-insulin to acid, adding alkali to give an insulin solution, e.g.
to a pH above 7, and spray-drying the insulin solution (which also
contains a salt formed as a result of the dissolution process, or a
buffer).
[0015] Preferably, the microparticles are
non-crystalline/amorphous.
DESCRIPTION OF THE INVENTION
[0016] As indicated above, microparticles of the invention "consist
essentially" of the therapeutic agent. This term is used herein to
indicate that they are substantially free of polysaccharide, or
buffer salt, e.g. citrate, since none is necessary. In general,
there will be no polysaccharide present at all, although an amount
of up to, say 10% by weight may be tolerated. The absence of
polysaccharide has the advantage that a given unit dosage, e.g. a
particle, contains essentially only the intended active component.
This is an important consideration, for a drug that may be required
in large amounts. Another advantage is the avoidance of delivering
unnecessary material to a subject. A further advantage is that
consistent dosing of the therapeutic agent is facilitated; this is
especially important where there is a narrow therapeutic
window.
[0017] The absence of buffer salt is desirable as it allows a more
concentrated feedstock solution of the active agent to be
spray-dried resulting in significant cost savings and providing a
more commercial-scale process to be adopted.
[0018] The term "substantially pure" is used herein to indicate
that the feedstock solution to be spray-dried comprises primarily
only therapeutic agent and solvent. Again, as described above,
there may be a minor amount of solids other than the active agent,
but this has no significant effect on the eventual stability of the
product.
[0019] Insulin microparticles of the invention may include
components that are produced during the successive addition of acid
and alkali, in preparation of the feedstock, e.g. a salt. For
example, NaCl is formed if the acid and alkali are respectively HCl
and NaOH. It has been found that the presence of NaCl apparently
has no stabilizing effect. Indeed stability may be greater with
reduced amounts of salt, again allowing a more concentrated
feedstock to be used.
[0020] Typically, the solution for spray-drying may contain less
than 4% by weight of salt, by weight of total solids. The salt
content is based on theoretical considerations, by titration to
pH7. More particularly, this value is calculated by consideration
of the molar quantities of the ions added during dissolution. The
solution may contain any desired amount of the therapeutic agent,
e.g. more than 20, 30 or 50 mg/ml, often up to 100 or 200
mg/ml.
[0021] As indicated above, successive addition of acid and alkali
apparently destroys the crystalline form of Zn insulin. Zn may
dissociate from the hexameric complex but need not be removed.
Accordingly, Zn may be present in the microparticles. If desired,
this or any other component, other than the therapeutic agent, may
be removed, using any suitable technique known to those of skill in
the art. In a preferred embodiment for insulin, the Zn is removed
from solution prior to spray-drying. This may be achieved by
diafiltering the solution according to methods known in the art.
The Zn-free insulin may have greater stability than the
Zn-containing product. Moisture may also be present.
[0022] As disclosed in more detail in WO-A-9218164, WO-A-9408627
and other Andaris publications, the conditions of spray-drying can
be controlled so that microparticles having a defined size range,
e.g. 0.1 to 50 .mu.M, can be obtained. The mass median particle
size is preferably 1 to 10 .mu.M, when the product is intended for
administration by inhalation.
[0023] The microparticles (microcapsules) obtained by spray-drying
may be solid or hollow. Further, the surface may be smooth or
"dimpled"; a dimpled surface may be beneficial for inhalation.
[0024] The microparticles have good stability and may be maintained
as such, i.e. as a dry powder, in a container. During storage or in
formulation, they may be mixed with any suitable pharmaceutical
agents, carriers, bulking agents etc., and they may be processed by
any technique desired to give a product having the properties
intended for the ultimate therapeutic use. In particular, the
formulation of particles for formulations that can be delivered to
the lung, e.g. using a metered dose or dry powder inhaler, are
known to those skilled in the art.
[0025] The nature of the container is not critical. For example, it
may be a glass jar or plastics box. It merely defines a storage
environment within which, unlike the prior art and as evidenced
below, there is no need to remove moisture or otherwise to control
the conditions.
[0026] The therapeutic agent may be any protein or peptide having a
desired therapeutic effect. Included within the definition of
proteins and peptides are functional derivatives, such as
glycoproteins. Typical examples of proteins that may be used
include enzymes, hormones and blood plasma products. DNase and
tryspin are specific examples. Others include growth hormone,
calcitonins, interferons, interleukin-1 receptor and low molecular
weight heparin.
[0027] The therapeutic agent may in particular be any of those
described in WO-A-9632149. Insulin that is used in the invention
may be of any suitable form. It may be, for example, bovine or
human insulin. Results that have been obtained, regarding the
stability of bovine insulin, apparently apply also to human
insulin.
[0028] The following Examples illustrate the invention.
EXAMPLE 1
[0029] A solution of bovine or human insulin for spray-drying is
typically prepared in the following way: 5 g insulin is dissolved
in 70 ml 0.05 m HCl, after which the solution is back-titrated with
sufficient 1M NaOH to reform a solution from the isoelectric point
precipitate. According to the final concentration required, water
is added to make to volume. Approximately 4.8 ml 1M NaOH is
required, in this Example. The solution is then spray-dried using a
Mini spray drier with an outlet temperature of approximately
87.degree. C. and a solution feed rate of approximately 0.75
g/min.
[0030] Reverse Phase High Performance Liquid Chromatography
(RP-HPLC) was used to assess the stability of insulin, under the
following conditions.
1 Column: Vydac C-18, 5 .mu.M, 30 nm Mobile Phase: A-0.1% TFA in
water B-0.1% TFA in acetonitrile (95%) and water (5%) Gradient
Elution Flow Rate: 1.5 mL/min Detection: UV at 220 nm Injection
Volume: 100 .mu.L
[0031] Under these conditions, bovine insulin has a retention time
of approximately 7.4 minutes.
[0032] A peak attributable to deamidated insulin is located at the
tailing edge of the main peak. The extent of deamidation is used to
indicate stability and is calculated by expressing the area of the
deamidation peak as a percentage of the total peak area. Total
degradation is expressed as the area of all degradant peaks as a
percentage of the total peak area.
2TABLE 1 Percentage Total Degradation and Deamidation of Non-Spray
Dried Bovine Crystalline Insulin 2.degree. C./Ambient RH 30.degree.
C./60% RH % % % % Time Deamidation Degradation Deamidation
Degradation Initial 3.2 3.6 3.2 3.6 1 month 3.5 3.9 4.2 5.3 3
months 4.4 5.6 5.8 11.0 6 months 3.4 4.5 6.7 13.7
[0033]
3TABLE 2 Percentage Total Degradation and Deamidation of Insulin
Microparticles 2.degree. C./Ambient RH 30.degree. C./60% RH % % % %
Time Deamidation Degradation Deamidation Degradation Initial 2.4
3.1 2.4 3.1 1 month 2.8 3.9 3.1 4.6 3 months 2.0 2.7 2.6 4.1 6
months 1.9 3.0 2.8 5.0
[0034] The results indicate that the extent of both deamidation and
total degradation is increased with time, for all the batches
evaluated. Additionally, the data suggest that spray drying appears
to confer additional stability to the protein, in that the bovine
crystalline insulin control suffers increased degradation in
comparison to the microparticle formulations at comparable
timepoints after storage at 30.degree. C./60% RH.
[0035] To investigate whether this was also seen with human
insulin, human insulin microparticles were prepared (by the same
general procedure as that described above) and placed on
accelerated stability at 40.degree. C./75% RH. All samples were
analysed by RP-HPLC at the initial time point, and also after 1
week, 2 weeks and 5 weeks.
4TABLE 3 Effect of Storage at 40.degree. C./75% RH on the
Deamidation and Total Degradation Levels of Human Insulin
Recombinant From E. Coli Storage Time At 40.degree. C./75% RH %
Deamidation % Total Degradation 0 0.59 0.75 1 1.57 4.27 2 1.62 5.15
5 2.37 8.40
[0036]
5TABLE 4 Effect of Storage at 40.degree. C./75% RH on the
Deamidation and Total Degradation Levels of Human Insulin
Microparticles Storage Time At 40.degree. C./75% RH % Deamidation %
Total Degradation 0 0.95 1.65 1 1.08 2.20 2 1.03 3.10 5 1.21
3.32
[0037] Comparing Tables 3 and 4, the microparticle formulation of
human insulin is less prone to degradation showing only 3.32% total
degradation after 5 weeks at 40.degree. C./75% RH compared to 8.40%
total degradation for the material stored as received under the
same conditions.
[0038] Pikal and Rigsbee (1997), supra, although working on a
lyophilized form of insulin, might be understood to substantiate
the findings reported herein.
EXAMPLE 2
[0039] A solution of bovine DNase (molecular mass 31 kD) for
spray-drying was prepared by dissolving the source material in
water containing 1 mM phenylmethylsulphonyl fluoride (PMSF). The
PMSF is present to inhibit proteolytic degradation. The resulting
feedback solution comprised 50 mg/ml DNase.
[0040] The solution was then spray-dried using a Mini spray drier
with an inlet temperature of 130.degree. C., an outlet temperature
of 85.degree. C. and a solution feed rate of approximately 0.8
ml/min. The activity was measured by the rate of increase of
spectrophotometric absorbance at 260 nm of DNA (hyperchromicity
assay), and HPLC gel permeation chromatography was used to assess
the physical stability.
[0041] Spray-dried DNase retained approximately 90% of its initial
activity and showed no change in physical stability. For
spray-dried material stored at 40.degree. C./75/% RH and 25.degree.
C./60% RH, and source material stored at 25.degree. C./60% RH,
there was comparable activity and physical stability at 4 and 8
weeks.
EXAMPLE 3
[0042] A solution of bovine trypsin (molecular mass 23.3 kD) for
spray-drying was prepared by dissolving the source material
(crystallized) in water. The resulting feedstock solution comprised
50 mg/ml trypsin.
[0043] The solution was then spray-dried as described in Example 2.
Activity was measured against azocasein substrate, and HPLC gel
permeation chromatography was used to assess the physical
stability.
[0044] Spray-dried trypsin retained approximately 100% of its
initial activity and showed no change in physical stability. A
comparison of spray-dried material stored at 4.degree. C.,
25.degree. C./60% RH and 40.degree. C./75% RH, and source material
stored at 25.degree. C./60% RH, showed substantially no loss in
activity or physical stability at 12 weeks.
EXAMPLE 4
[0045] A solution of reduced gluthathione (a peptide of molecular
mass 307D) for spray-drying was prepared by dissolving the
crystalline source material in water. The resulting feedstock
solution comprised 100 mg/ml reduced glutathione.
[0046] The solution was spray-dried using a Buchi Mini B-191
spray-drier with an inelt temperature of 100.degree. C., an outlet
temperature of 74.degree. C., and a solution feed-rate of
approximately 1 ml/min. Spray-drying using either compressed air or
nitrogen for atomization of the fluid stream did not result in a
significant increase in the level of oxidised glutathione
(initially present at 0.8% w/w, increasing to 0.9% w/w).
* * * * *