(12> Ulllted States Patent
`Ramstack et al.
`
`US006495164B1
`(16) Patent N6.=
`US 6,495,164 B1
`(45) Date of Patent:
`Dec. 17, 2002
`
`(54) PREPARATION OF INJECTABLE
`
`FOREIGN PATENT DOCUMENTS
`
`igggggglgegigAvlNelMPRovEn
`
`EP W0
`
`WO 89/03678
`
`5/1989
`
`5/1994
`“100924316332; A1 W0 94/10982
`W0
`
`W0 IB—WO 94/25460 A1 11/1994
`WO IB—WO 95/13799 A1
`5/1995
`W0
`WO 95/13799
`5/1995
`W0 IB—WO 96/01652 A1
`1/1996
`W0
`W0 96/40049
`12/1996
`W0
`WO 97/41837
`11/1997
`W0 IB—WO 97/44039 A1 11/1997
`W0
`W0 99/12549
`3/1999
`W0 IB—WO 99/25354 A2
`5/1999
`
`OTHER PUBLICATIONS
`
`M. J. Akers et al., “Formulation Design and Development to
`Parenteral Suspensions,” Journal of Parenteral Science and
`Technology, vol. 41, No. 3, May—Jun. 1987, pp. 88—96.
`Beck, L.R., et al., Biology of Reproduction, 28:186—195
`(Feb' 1983),
`Bodmeier, R., et al., International Journal of Pharmaceuti
`
`_
`_
`_
`_
`“151431797186(1988);,
`Stamslav Cajavec et al., The primary chicken vaccination
`against Newcastle disease With antigenic virus subunits
`Prepared in a Water—in—0?—in—water emulsion? Periodicum
`Biologorum, vol. 99, No. 1, pp. 39—44, 1997.
`Y. Cha and CG. Pitt, “The Acceleration of Degradation
`Controlled Drug Delivery from Polyester Microspheres,”
`Journal of Controlled Release, 8(1989) 259—265.
`Y. Cha and CG. Pitt, “A One—Week Subdermal Delivery
`_
`_
`System for L—Methadone Based on Biodegradable Micro
`particles,” Journal of Controlled Release, 7 (1988) 69—78.
`“HoW to Avoid Clogging of Insulin Syringes,” Diabetes
`Forecase, NOV__DeC_ 1976, pp 27_29_
`1 7 N 3
`R J 1.1
`t
`1 J
`1 fM.
`1t.
`' a1 e M Ourna O
`lcroencapsualon’vo' >
`0' >
`Jul-$69 1990,PP- 297—319
`Wen—I Li et al., Journal of Controlled Release, 37:199—214
`(Dec' 1995)'
`
`(List Continued on next page)
`
`Primary Examiner_Thurman K' Page
`Assistant Examiner—Rachel M. Bennett
`(74)_A”Omey) Agent) 0’ F"m_Andrea 6' Raster;
`Covmgton & Burhng
`
`(57)
`ABSTRACT
`Injectable compositions having improved injectability. The
`injectable compositions include microparticles suspended in
`an aqueous injection vehicle having a viscosity of at least 20
`cp at 20° C. The increased viscosity of the injection vehicle
`that constitutes the ?uid phase of the suspension signi?
`cantly reduces in vivo injectability failures. The injectable
`compositions can be made by mixing dry microparticles
`With an aqueous injection vehicle to form a suspension, and
`then mixing the suspension With a viscosity enhancing agent
`to increase the viscosity of the ?uid phase of the suspension
`to the desired level for improved injectability.
`
`53 Claims, No Drawings
`
`(75) Inventors: J. Michael Ramstaclk, Lebanon, OH (Us); M- Gary L Rlley, cambrldge,
`
`MA (US); Stephen E- Zale, Hopklnton,
`MA (US); Joyce M. Hotz, Cincinnati,
`OH (US); Olufunmi L. Johnson,
`Cambridge, M A (Us)
`
`(73) Assignee: Alkermes Controlled Therapeutics,
`Inc 1, Cambridge, MA (Us)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`USC 154(k)) by 0 days'
`
`(21) Appl' NO” 09/577’875
`(22) Filed:
`May 25, 2000
`
`(51) Int. Cl.7 .......................... .. A61K 9/14; A61K 9/08;
`A61K 9/16
`
`(52) US. Cl. ..................... .. 424/489; 424/490; 424/497;
`424/486; 424/484; 42 4 /49 4
`
`(58) Field of Search ............................... .. 424/484, 490,
`424/497, 486
`
`(56)
`
`_
`References Clted
`U.S. PATENT DOCUMENTS
`
`3,523,906
`3 691 090
`3,700,215
`3,737,337
`3,773,919
`3,891,570
`3,960,757
`4,221,862
`4,384,975
`4,389,330
`
`4,530,840
`
`4,818,517
`4,940,588
`5,066,436
`
`5,428,024
`5,478,564
`5,541,172
`5,612,346
`
`’
`’
`5,654,010
`
`576587593
`5,667,808
`5,688,801
`5,747,058
`57770231
`577927477
`5’871’778
`5,916,598
`5,942,253
`5,965,168
`
`8/1970 Vrancken et al. ......... .. 252/316
`9/1972 Kitajima et a1_
`252/316
`* 10/1972 Hardman et a1_
`259/98
`6/1973 Schnofing et a1~
`117/100
`11/1973 Boswell et a1.
`424/19
`6/1975 Fukushima et al. ..
`252/316
`6/1976 Morishita etal.
`252/316
`9/1980 Naito et a1. ............ .. 430/536
`5/1983 Fong ....... ..
`.. 427/213.36
`6/1983 Tice et al. . . . . .
`. . . .. 427/213.36
`
`7/1985 Tice et a1. . . . . .
`
`. . . . . .. 514/179
`
`424/488
`424/490
`264/4.3
`
`. . . .. 514/21
`424/426
`514/169
`514/258
`
`4/1989 KWee et al.
`7/1990 Sparks et al. ..
`11/1991 Komen et al.
`E2212? et a1‘ '
`6/1995 Chu et al. . . . . . .
`12/1995 Wantier et al.
`7/1996 Labric et al.
`* 3/1997 Mesens et al.
`;/
`?anéstack etl a1‘
`/
`/
`er en et a '
`.. 424/502
`8/1997 Johnson et al.
`424/484
`'
`8/1997 Bernstein et a1
`* 8/1997 Kim) et aL _______________ __ 424/489
`8/1997 Orly et a1_
`424/499
`9/1997 Johnson et a1,
`424/501
`11/1997 Mesens et al.
`514/258
`5/ 1998 Tipton et al- ------------- -- 424/423
`6/1998 Mesens et a1- ~~~~~~~~~~~~ " 424/497
`8/1998 Rlckey et a1‘ '
`424/501
`2/1999 Klno et a1‘
`424/489
`6/1999 Rickey et al.
`424/501
`8/1999 GombotZ et al.
`424/501
`10/1999 Mesens et a1. ............ .. 424/497
`
`>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
`
`LUYE1015
`IPR of Patent No. 6,667,061
`
`

`
`US 6,495,164 B1
`Page 2
`
`OTHER PUBLICATIONS
`H. V. Maulding et al., “Biodegradable Microcapsules:
`Acceleration of Polymeric EXcipient Hydrolytic Rate by
`Incorporation of a Basic Medicament,” Journal of Con
`trolled Release, 3:103—117 (Mar. 1986).
`Pharmaceutical Dosage Forms Disperse Systems, edited by
`Herbert A. Lieberman, Martin M. Rieger, Gilbert I. Bank,
`Second edition, Chapter 7, “Injectable Emulsions and Sus
`pensions,” 1:261—318.
`Pharmaceutical Dosage Forms Disperse Systems, edited by
`Herbert A. Lieberman, Martin M. Rieger, Gilbert I. Bank,
`Second edition (1996), Chapter 7, “Viscosity—Impairing
`Agents in Disperse Systems,” 2:287—313.
`
`Hongkee Sah et al., Pharmaceutical Research, 13:360—367
`(Mar. 1996).
`Toyomi Sato et al., Pharmaceutical Research, 5:21—30
`(1988).
`J. R. Zingerman et al., “Automatic injector apparatus for
`studying the injectability of pareteral formulations for ani
`mal health,” International Journal of Pharmaceuticals, 36
`(1987) 141—145
`
`* cited by examiner
`
`LUYE1015
`IPR of Patent No. 6,667,061
`
`

`
`US 6,495,164 B1
`
`1
`PREPARATION OF INJECTABLE
`SUSPENSIONS HAVING IMPROVED
`INJECTABILITY
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention relates to preparation of injectable
`compositions. More particularly, the present invention
`relates to injectable suspensions having improved
`injectability, and to methods for the preparation of such
`injectable suspensions.
`2. Related Art
`Injectable suspensions are heterogeneous systems that
`typically consist of a solid phase dispersed in a liquid phase,
`the liquid phase being aqueous or nonaqueous. To be effec
`tive and pharmaceutically acceptable, inj ectable suspensions
`should preferably be: sterile; stable; resuspendable; syringe
`able; injectable; isotonic; and nonirritating. The foregoing
`characteristics result in manufacturing, storage, and usage
`requirements that make injectable suspensions one of the
`most difficult dosage forms to develop.
`Injectable suspensions are parenteral compositions in that
`they are introduced into an organism or host by means other
`than through the gastrointestinal tract. Particularly, inject
`able suspensions are introduced into a host by subcutaneous
`(SC) or intramuscular (IM) injection. Injectable suspensions
`may be formulated as a ready-to-use injection or require a
`reconstitution step prior to use. Injectable suspensions typi
`cally contain betWeen 0.5% and 5.0% solids, With a particle
`siZe of less than 5 pm for IM or SC administration.
`Parenteral suspensions are frequently administered through
`needles about one-half to tWo inches long, 19 to 22 gauge,
`With an internal diameter in the range of 700 to 400 microns,
`respectively.
`To develop an effective and pharmaceutically acceptable
`injectable suspension, a number of characteristics must be
`evaluated. These characteristics include syringeability,
`injectability, clogging, resuspendability, and viscosity. As
`Will be readily apparent to one skilled in the art, other
`characteristics and factors should be considered in develop
`ing an injectable suspension (see, for example, Floyd, A. G.
`and Jain, S., Injectable Emulsions and Suspensions, Chapter
`7 in Pharmaceutical Dosage Forms: Disperse Systems Vol.
`2, Edited by Lieberman, H. A., Rieger, M. M., and Banker,
`G. S., Marcel Dekker, NeW York (1996), the entirety of
`Which is incorporated herein by reference and referred to
`herein as “the Floyd et al. Chapter”).
`Syringeability describes the ability of an injectable sus
`pension to pass easily through a hypodermic needle on
`transfer from a vial prior to injection. It includes character
`istics such as ease of WithdraWal, clogging and foaming
`tendencies, and accuracy of dose measurements. As
`described in the Floyd et al. Chapter, increase in the
`viscosity, density, particle siZe, and concentration of solids
`in suspension hinders the syringeability of suspensions.
`Injectability refers to the performance of the suspension
`during injection. Injectability includes factors such as pres
`sure or force required for injection, evenness of 110W, aspi
`ration qualities, and freedom from clogging.
`Clogging refers to the blockage of syringe needles While
`administering a suspension. It may occur because of a single
`large particle, or an aggregate that blocks the lumen of the
`needle due to a bridging effect of the particles. Clogging at
`or near the needle end may be caused by restrictions to How
`
`2
`from the suspension. This may involve a number of factors,
`such as the injection vehicle, Wetting of particles, particle
`siZe and distribution, particle shape, viscosity, and flow
`characteristics of the suspension.
`Resuspendability describes the ability of the suspension
`to uniformly disperse With minimal shaking after it has stood
`for some time. Resuspendability can be a problem for
`suspensions that undergo “caking” upon standing due to
`settling of the de?occulated particles. “Caking” refers to a
`process by Which the particles undergo groWth and fusion to
`form a nondispersible mass of material.
`Viscosity describes the resistance that a liquid system
`offers to flow when it is subjected to an applied shear stress.
`A more viscous system requires greater force or stress to
`make it flow at the same rate as a less viscous system. A
`liquid system Will exhibit either NeWtonian or non
`NeWtonian ?oW based on a linear or a non-linear increase,
`respectively, in the rate of shear With the shearing stress.
`Structured vehicles used in suspensions exhibit non
`NeWtonian How and are typically plastic, pseudoplastic, or
`shear-thinning With some thixotropy (exhibiting a decrease
`in viscosity With an increase in the rate of shear).
`In design of injection vehicles, viscosity enhancers are
`added in order to retard settling of the particles in the vial
`and syringe. HoWever, viscosity is typically kept loW, in
`order to facilitate mixing, resuspension of the particles With
`the vehicle, and to make the suspension easier to inject (i.e.,
`loW force on the syringe plunger). For example, Lupron
`Depot from TAP Pharmaceuticals (mean particle siZe of
`approximately 8 pm) utiliZes an injection vehicle With a
`viscosity of approximately 5.4 cp. The ?uid phase of a
`suspension of Decapeptyl from DebioPharm (mean particle
`siZe of approximately 40 pm), When prepared as directed,
`has a viscosity of approximately 19.7 cp. Conventional
`parenteral suspensions are dilute, With limitations for vis
`cosity because of syringeability and injectability constraints.
`See, for example, the Floyd, et al. Chapter noted above.
`Injectable compositions containing microparticle prepa
`rations are particularly susceptible to injectability problems.
`Microparticle suspensions may contain 10—15% solids, as
`compared With 0.5—5% solids in other types of injectable
`suspensions. Microparticles, particularly controlled release
`microparticles containing an active agent or other type of
`substance to be released, range in siZe up to about 250 pm,
`as compared With a particle siZe of less than 5 pm recom
`mended for IM or SC administration. The higher concen
`tration of solids, as Well as the larger solid particle siZe,
`make it more difficult to successfully inject microparticle
`suspensions. This is particularly true since it is also desired
`to inject the microparticle suspensions using as small a
`needle as possible to minimiZe patient discomfort.
`Thus, there is a need in the art for an injectable compo
`sition With improved injectability. There is a particular need
`in the art for an injectable composition that solves the
`injectability problems associated With microparticle suspen
`sions. The present invention, the description of Which is
`fully set forth beloW, solves the need in the art for such
`injectable compositions.
`
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`55
`
`SUMMARY OF THE INVENTION
`The present invention relates to injectable compositions
`having improved inj ectability, and to methods for the prepa
`ration of such injectable compositions. In one aspect of the
`invention, a composition suitable for injection through a
`needle into a host is provided. The composition comprises
`microparticles having a polymeric binder, With a mass
`
`65
`
`LUYE1015
`IPR of Patent No. 6,667,061
`
`

`
`US 6,495,164 B1
`
`3
`median diameter of at least about 10 pm. The composition
`also includes an aqueous injection vehicle (the injection
`vehicle not being the aqueous injection vehicle that consists
`of 3% by volume sodium carboXymethyl cellulose, 1% by
`volume polysorbate 20, 0.9% by volume sodium chloride,
`and a remaining percentage by volume of Water). The
`microparticles are suspended in the injection vehicle at a
`concentration of greater than about 30 mg/ml to form a
`suspension, the ?uid phase of the suspension having a
`viscosity of at least 20 cp at 20° C. In other embodiments,
`the ?uid phase of the suspension has a viscosity at 20° C. of
`at least about 30 cp, 40 cp, 50 cp, and 60 cp. The compo
`sition may also comprise a viscosity enhancing agent, a
`density enhancing agent, a tonicity enhancing agent, and/or
`a Wetting agent. The composition can be administered to a
`host by injection.
`In another aspect of the present invention, a method of
`making a composition suitable for injection through a needle
`into a host is provided. The method comprises:
`(a) providing microparticles comprising a polymeric
`binder, said microparticles having a mass median diam
`eter of at least about 10 pm;
`(b) providing an aqueous injection vehicle having a
`viscosity of at least 20 cp at 20° C., Wherein said
`injection vehicle is not the aqueous vehicle consisting
`of 3% by volume sodium carboXymethyl cellulose, 1%
`by volume polysorbate 20, 0.9% by volume sodium
`chloride, and a remaining percentage by volume of
`Water; and
`(c) suspending the microparticles in the aqueous injection
`vehicle at a concentration of greater than about 30
`mg/ml to form a suspension.
`In a further aspect of the present invention, another
`method for preparing a composition suitable for injection
`through a needle into a host is provided. In such a method,
`dry microparticles are miXed With an aqueous injection
`vehicle to form a ?rst suspension. The ?rst suspension is
`miXed With a viscosity enhancing agent to form a second
`suspension. The viscosity enhancing agent increases the
`viscosity of the ?uid phase of the second suspension. The
`?rst suspension may be WithdraWn into a ?rst syringe, prior
`to miXing With the viscosity enhancing agent. The ?rst
`suspension may be miXed With the viscosity enhancing agent
`by coupling the ?rst syringe containing the ?rst suspension
`to a second syringe that contains the viscosity enhancing
`agent. The ?rst suspension and the viscosity enhancing agent
`are then repeatedly passed betWeen the ?rst and second
`syringes.
`In yet a further aspect of the present invention, a method
`for administering a composition to a host is provided. The
`method comprises:
`(a) miXing dry microparticles With an aqueous injection
`vehicle to form a ?rst suspension;
`(b) miXing the ?rst suspension With a viscosity enhancing
`agent to form a second suspension, Wherein the vis
`cosity enhancing agent increases the viscosity of the
`?uid phase of the second suspension; and
`(c) injecting the second suspension into the host.
`In still a further aspect of the present invention, another
`method for administering a composition to a host is pro
`vided. The method comprises:
`(a) miXing dry microparticles With an aqueous injection
`vehicle to form a suspension, Wherein the aqueous
`injection vehicle has a viscosity at 20° C. of less than
`about 60 cp;
`(b) changing the viscosity of the ?uid phase of the
`suspension;
`
`10
`
`15
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`20
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`25
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`30
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`35
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`4
`(c) WithdraWing the suspension into a syringe; and
`(d) injecting the suspension from the syringe into the host.
`In a further aspect of the invention, step (b) is carried out
`by changing the temperature of the ?uid phase of the
`suspension. In another aspect, step (c) is performed prior to
`step
`Step (b) may be carried out by adding a viscosity
`enhancing agent to the suspension in the syringe to thereby
`increase the viscosity of the ?uid phase of the suspension.
`In still a further aspect of the invention, a method for
`preparing a composition suitable for injection through a
`needle into a host is provided. The method comprises:
`(a) miXing dry microparticles With an aqueous injection
`vehicle that comprises a viscosity enhancing agent to
`form a suspension;
`(b) removing Water from the suspension; and
`(c) reconstituting the suspension With a quantity of sterile
`Water for injection to form an injectable suspension,
`Wherein the quantity of sterile Water for injection is
`suf?cient to achieve a viscosity of a ?uid phase of the
`injectable suspension that provides injectability of the
`composition through a needle ranging in diameter from
`18—22 gauge.
`
`Features and Advantages
`A feature of the present invention is that the injectable
`compositions can be used to inject varying types of
`microparticles, and varying types of active agents or other
`substances, into a host.
`A further feature of the present invention is that it alloWs
`microparticles to be Wetted to achieve a homogeneous
`suspension, While improving injectability into a host and
`reducing in vivo injectability failures.
`The present invention advantageously provides medically
`acceptable injectability rates for high concentration
`suspensions, and for suspensions having large particle siZe.
`The present invention also advantageously provides an
`ef?cient method of improving in vivo injectability Without
`introducing microbial contamination or compromising asep
`tic conditions.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`OvervieW
`The present invention relates to injectable compositions
`having improved inj ectability, and to methods for the prepa
`ration of such injectable compositions. The injectable com
`positions of the present invention overcome injectability
`problems, particularly injectability failures that occur upon
`injection into muscle or subcutaneous tissue. Such inject
`ability failures Will be referred to herein as “in vivo inject
`ability failures.” In vivo injectability failures often manifest
`themselves in the form of a plug at the tip of the needle, and
`occur immediately or shortly after injection has been initi
`ated. In vivo injectability failures are typically not predicted
`by laboratory or other in vitro testing.
`The inventors have unexpectedly discovered that inject
`ability is improved, and in vivo injectability failures signi?
`cantly and unexpectedly reduced, by increasing the viscosity
`of the ?uid phase of an injectable suspension. This is in
`contrast to conventional teachings that an increase in the
`viscosity hinders injectability and syringeability.
`Viscous vehicles, hoWever, are not optimal for preparing
`homogeneous suspensions of microparticles because of the
`relative inability of viscous vehicles to penetrate and Wet out
`
`LUYE1015
`IPR of Patent No. 6,667,061
`
`

`
`US 6,495,164 B1
`
`5
`a mass of dry particles. Suspensions prepared With viscous
`vehicles are prone to clump irreversibly. Consequently, such
`suspensions are not injectable via needles of medically
`acceptable siZe. A further disadvantage of viscous suspen
`sions is the lack of ease of transferring such suspensions
`from the vial or container used to prepare the suspension to
`the syringe used for injection.
`The present invention also solves the additional problems
`that arise from use of a viscous injection vehicle. In accor
`dance With the present invention, microparticles are sus
`pended in an injection vehicle having suitable Wetting
`characteristics. The viscosity of the ?uid phase of the
`injectable suspension is increased prior to injecting the
`suspension in order to improve injectability, and to reduce in
`vivo injectability failures.
`To ensure clarity of the description that folloWs, the
`folloWing de?nitions are provided. By “microparticles” or
`“microspheres” is meant particles that contain an active
`agent or other substance dispersed or dissolved Within a
`polymer that serves as a matrix or binder of the particle. The
`polymer is preferably biodegradable and biocompatible. By
`“biodegradable” is meant a material that should degrade by
`bodily processes to products readily disposable by the body
`and should not accumulate in the body. The products of the
`biodegradation should also be biocompatible With the body.
`By “biocompatible” is meant not toxic to the body, is
`pharmaceutically acceptable, is not carcinogenic, and does
`not signi?cantly induce in?ammation in body tissues. As
`used herein, “body” preferably refers to the human body, but
`it should be understood that body can also refer to a
`non-human animal body. By “Weight %” or “% by Weight”
`is meant parts by Weight per hundred parts total Weight of
`microparticle. For example, 10 Wt. % active agent Would
`mean 10 parts active agent by Weight and 90 parts polymer
`by Weight. Unless otherWise indicated to the contrary, per
`centages (%) reported herein are by volume. By “controlled
`release microparticle” or “sustained release microparticle” is
`meant a microparticle from Which an active agent or other
`type of substance is released as a function of time. By “mass
`median diameter” is meant the diameter at Which half of the
`distribution (volume percent) has a larger diameter and half
`has a smaller diameter.
`
`METHOD AND EXAMPLES
`
`The folloWing examples are provided to explain the
`invention, and to describe the materials and methods used in
`carrying out the invention. The examples are not intended to
`limit the invention in any manner.
`
`Example 1—In vitro Sieve Test Study
`
`To evaluate in vivo injectability failures, an in vitro sieve
`test study Was conducted to assess and predict in vivo
`injectability, and to determine the key factors affecting
`injectability. The folloWing factors Were investigated during
`the in vitro sieve test study: injection vehicle formulation;
`microparticle morphology; needle diameter; suspension
`concentration; and particle siZe as exhibited by sieve screen
`siZe used to screen the microparticles during the manufac
`turing process.
`Three batches of risperidone microparticles Were manu
`factured at a 125 gm scale using a process substantially the
`same as that disclosed in US. Pat. No. 5,792,477, the
`entirety of Which is incorporated herein by reference (see,
`for example, Example 1 in US. Pat. No. 5,792,477). Three
`batches of risperidone microparticles Were manufactured at
`a 1 Kg scale using the process described beloW in Example
`7. All batches had similar particle siZes (ranging from a
`Mass Median Diameter of 91 pm to 121 pm) based on
`
`6
`Hyac-Royco analysis of representative bulk material sieved
`through a 180 pm sieve screen. A 160 mg or 320 mg quantity
`of the microparticles (equivalent to a 50 or 100 mg dose of
`the risperidone active agent) Was transferred, using a manual
`Perry poWder ?ller With a 5/16 inch ID barrel, into a 5 cc glass
`vial, and capped With a Te?on lined septum.
`TWo injection vehicles Were used in the in vitro sieve test
`study. The ?rst injection vehicle (“Formula 1”) Was an
`aqueous vehicle consisting of 1.5% by volume carboxym
`ethyl cellulose (CMC), 30% by volume sorbitol, and 0.2%
`by volume TWeen 20 (polysorbate 20). The viscosity of the
`?rst injection vehicle Was approximately 27 cp at 20° C. The
`second injection vehicle (“Formula 2”) Was an aqueous
`vehicle consisting of 0.75% by volume CMC, 15% by
`volume sorbitol, and 0.2% by volume TWeen 20
`(polysorbate 20). The viscosity of the second injection
`vehicle Was approximately 7 cp at 20° C.
`The microparticle suspension Was prepared as folloWs.
`The injection vehicle Was aspirated into a 5 cc syringe
`through a needle. The vehicle Was then injected into the
`glass vial containing the microparticles, and the needle Was
`removed. The glass vial Was then rolled betWeen the palms
`until the microparticles Were completely suspended,
`approximately one minute. The needle Was reinserted into
`the vial so that the bevel of the needle Was just through the
`septum With the opening facing toWard the vial bottom. The
`vial Was inverted and the suspension Was WithdraWn. The
`syringe Was rotated 180° around its axis, and the remaining
`suspension Was aspirated into the syringe.
`Sieve screens With mesh opening siZes of 180, 212, 250,
`300, 355, and 425 pm Were used. The bevel of the syringe
`needle Was placed on the mesh of the sieve screen so that the
`bevel Was in full contact With the mesh. The needle Was
`oriented so the opening of the needle Was ?ush against the
`mesh of the screen. This prevented the mesh from entering
`the bevel, While maintaining the required restrictive area.
`The suspension Was tried on the smallest sieve mesh ?rst
`(highest screen resistance). If the suspension fouled the
`needle on this sieve mesh, the needle Was unclogged by
`retracting the plunger of the syringe, depressing the plunger
`While the syringe Was in the upWard position, and passing an
`aliquot of suspension through the needle. The injection
`process Was tried again using the next greater mesh siZe, and
`repeated until the suspension Was successfully injected. All
`preparations Were done in triplicate.
`A three-factor Box-Behnken statistical designed experi
`ment Was constructed to evaluate the folloWing independent
`variables: manufacturing bulk sieve siZe (125, 150, and 180
`pm); needle ID (19 TW, 20 RW, and 22 RW gauge—ID of
`19 TW (thin Wall) equivalent to 18 RW (regular Wall)); and
`suspension concentration (0.074, 0.096, and 0.138 W/W—
`responds to approximately 300 mg microparticle dose
`diluted With 4, 3, and 2 cc, respectively, of injection vehicle).
`The folloWing scoring system Was used:
`
`Score
`
`Result
`
`Needle Block
`Passes through a 425 ,um screen
`Passes through a 355 ,um screen
`Passes through a 300 ,um screen
`Passes through a 250 ,um screen
`Passes through a 212 ,um screen
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Table 1 beloW shoWs the score obtained for screen resis
`tance tests using this scoring system for the 1 Kg and the 125
`gm batches for each of the injection vehicles tested.
`
`LUYE1015
`IPR of Patent No. 6,667,061
`
`

`
`US 6,495,164 B1
`
`TABLE 1
`
`Mean Score
`
`Mfg Bulk Sieve Size
`
`n
`
`Formula 2 ~ 7 cp
`
`Formula 1 ~ 27 cp
`
`1 Kg Batches
`
`<180
`<125
`125 Gm Batches
`
`<180
`<150
`<125
`
`9
`9
`
`6
`6
`6
`
`2.3
`3.4
`
`1.5
`3.0
`3.0
`
`2.3
`3.7
`
`2.0
`2.8
`2.5
`
`As shown in Table 1, the screen resistance tests showed no
`signi?cant difference between the two injection vehicles
`tested. Variations in suspension concentration and injection
`vehicle viscosity showed little to no effect. For the 1 Kg
`Batches, the mean scores were identical for the <180 manu
`facturing bulk sieve size, even though the viscosity of the
`Formula 1 injection vehicle was approximately 27 cp, and
`the viscosity of the Formula 2 injection vehicle was signi?
`cantly less, approximately 7 op. The scores for the other 1
`Kg Batch and for the 125 Gm Batches varied modestly (0.2
`to 0.5) between to the two injection vehicles, thereby
`indicating that the injection vehicle viscosity had little effect.
`The tests conducted during the in vitro sieve test study show
`that in vitro injectability is strongly controlled by micropar
`ticle morphology and size. Needle gauge had a more modest
`effect. As will be discussed in more detail below, in vivo data
`supported the responses of microparticle morphology, size,
`and suspension concentration, but contradicted the effect of
`injection vehicle viscosity. Particularly, the in vivo studies
`showed a dramatic improvement in injectability with
`increased injection vehicle viscosity.
`In vivo Injectability
`Example 2—Pig Study
`The injectability of risperidone microparticles was evalu
`ated in Yorkshire weanling pigs. The study revealed that the
`IM injectability of risperidone microparticles is dependent
`upon injection vehicle viscosity and microparticle size.
`Reducing the injection vehicle viscosity led to a higher rate
`of injection failures due to needle clogging.
`Risperidone microparticles were manufactured at the 125
`gm scale in the same manner noted above for the in vitro
`sieve test study. The microparticles were sized to <125 pm
`and <150 pm using USA Standard Testing Sieves Nos. 120
`and 100, respectively. The same two injection vehicles
`(Formula 1 and Formula 2) described above for the in vitro
`sieve test study were used in the pig study. 19 gauge TW><1.5
`inch hypodermic needles (Becton-Dickinson Precision
`glide® catalog number 305187) and 3 cc hypodermic
`syringes (Becton-Dickinson catalog number 309585) were
`used.
`The injection experiments were conducted in male and
`female Yorkshire weanling pigs approximately 6 weeks in
`age (10—15 kg). The animals were anesthetized with low
`doses of Telazole and Xylazine and with halothane if
`needed. Injection sites were shaved and cleansed with beta
`dine swabs prior to microparticle administration.
`Injections to the hind quarters were administered to the
`biceps femoris in the upper hind limb. Injection sites in the
`legs were to the super?cial digital ?exor muscles in the
`forelimb, and to the cranial tibial muscle in the hindlimb.
`Microparticles and injection vehicles were equilibrated to
`ambient temperature for at least 30 minutes. Using a 3 ml
`syringe equipped with a 1.5 inch 19 gauge thin wall needle,
`the prescribed volume of injection vehicle was withdrawn
`
`8
`into the syringe, and injected into the vial containing the
`microparticles. The microparticles were suspended in the
`injection vehicle by orienting the vial horizontally and
`rolling it between the palms of the operator’s hands. This
`was done without removing the needle/syringe from the
`septum. The time required to fully suspend the micropar
`ticles was approximately one minute.
`The suspended microparticles were then withdrawn into
`the same needle/syringe and injected. Following insertion of
`the needle and prior to injection of the suspension, the
`syringe plunger was withdrawn slightly to con?rm that the
`needle was located in the extravascular space. The time
`interval between aspiration of the suspension and injection
`was usually less than one minute. Injection regions were
`evaluated to pinpoint the site of microparticle deposition and
`to assess the distribution of microparticles in the tissue.
`Table 2 below shows the effect on injectability as a
`function of injection vehicle viscosity, injection site, and
`microparticle concentration. A vehicle viscosity of “high”
`refers to the injection vehicle of Formula 1 described above,
`having a viscosity of approximately 27 cp at 20° C.
`Similarly, a vehicle viscosity of “low” refers to the injection
`vehicle of Formula 2 described above, having a viscosity of
`approximately 7 cp at 20° C. The size of the microparticles
`for the results shown in Table 2 is 180 pm.
`
`10
`
`15
`
`20
`
`25
`
`TABLE 2
`
`Vehicle
`Viscosity
`
`Microparticle
`Dose
`
`Volume Site
`
`Failure rate
`
`30
`
`High
`High
`Low
`High
`
`160 mg
`160 mg
`160 mg
`320 mg
`
`1 mL Hind quarter
`1 mL Leg
`1 mL Hind quarter
`1 mL Hind quarter
`
`0/10
`1/8
`4/7
`0/4
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`As can be seen from Table 2, increased failure rates were
`observed with the lower viscosity injection vehicle (4 fail
`ures with 7 injections), and when the injection site was in the
`leg (1 failure per 8 injections). The increased failure rate due
`