111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US008268299B2
`
`c12) United States Patent
`Kabra et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,268,299 B2
`Sep.18,2012
`
`(54) SELF PRESERVED AQUEOUS
`PHARMACEUTICAL COMPOSITIONS
`
`(75)
`
`Inventors: Bhagwati P. Kabra, Euless, TX (US);
`Masood A. Chowhan, Arlington, TX
`(US); L. Wayne Schneider, Crowley,
`TX (US); Wesley Wehsin Han,
`Arlington, TX (US)
`
`(73) Assignee: Alcon Research, Ltd., Fort Worth, TX
`(US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 754 days.
`
`(21) Appl. No.: 11/858,781
`
`(22) Filed:
`
`Sep.20,2007
`
`(65)
`
`Prior Publication Data
`
`US 2008/0075790 AI
`
`Mar. 27, 2008
`
`Related U.S. Application Data
`
`(60) Provisional application No. 60/827,411, filed on Sep.
`28, 2006, provisional application No. 60/826,529,
`filed on Sep. 21, 2006.
`
`(51)
`
`Int. Cl.
`A61K 31174
`(2006.01)
`A61K 33132
`(2006.01)
`A61K 33122
`(2006.01)
`A01N 25/00
`(2006.01)
`A01N 59/16
`(2006.01)
`A01N 59/14
`(2006.01)
`(52) U.S. Cl. ..................... 424/78.04; 424/405; 424/641;
`424/657; 424/659; 424/660; 514/912
`(58) Field of Classification Search ........................ None
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`4,522,806 A
`6/1985 Muhlemann eta!.
`5,130,298 A
`7/1992 Cini eta!.
`5,221,664 A
`6/1993 Berkowitz eta!.
`5,320,843 A
`6/1994 Raheja eta!.
`5,352,708 A
`10/1994 Woodward et al.
`6/1995 Dziabo eta!.
`5,424,078 A
`5,460,834 A
`10/1995 Bhagat
`111997 Olejnik et al.
`5,597,559 A
`5,607,698 A
`3/1997 Martin eta!.
`5,683,993 A
`1111997 Tsao
`5,725,887 A
`3/1998 Martin eta!.
`5,736,165 A
`4/1998 Ripley et a!.
`5,741,817 A
`4/1998 Chowhan eta!.
`5,817,277 A
`10/1998 Mowrey-McKee eta!.
`5,820,822 A *
`10/1998 Kross .............................. 422/37
`5,843,891 A *
`12/1998 Sherman ....................... 424/456
`5,858,346 A
`111999 Vehige eta!.
`5,858,996 A
`111999 Tsao
`6,017,861 A
`112000 Fujiwara et al.
`6,024,954 A
`212000 Park eta!.
`6,034,043 A
`3/2000 Fujiwara et al.
`9/2000 Nair eta!.
`6,121,315 A
`6,143,799 A
`1112000 Chowhan eta!.
`6,319,464 B1
`1112001 Asgharian
`
`6,348,190 B1
`6,482,799 B1
`6,492,361 B1
`6,503,497 B2
`6,583,124 B2
`7,074,827 B2
`7,445,771 B2
`2002/0098160 A1
`2002/0122831 A1
`2002/0123482 A1 *
`2005/0129771 A1
`2005/0214382 A1
`2006/0205725 A1
`2006/0270735 A1 *
`2007/0212420 A1
`2007/0297990 A1
`2010/0227003 A1
`
`212002 Illes et a!.
`1112002 Tuse et a!.
`12/2002 Muller eta!.
`112003 Chowhan eta!.
`6/2003 Asgharian
`7/2006 Ueno
`1112008 Dassanayake et a!.
`7/2002 Chowhan eta!.
`9/2002 Mowrey-McKee eta!.
`9/2002 Chowhan eta!. ............... 514/59
`6/2005 Asgharian
`9/2005 Xia et al.
`9/2006 Ueno
`1112006 Deaciuc et al ................ 514/530
`9/2007 Xia et al.
`12/2007 Shah eta!.
`9/2010 Shah eta!.
`
`JP
`wo
`wo
`wo
`wo
`wo
`
`FOREIGN PATENT DOCUMENTS
`2003-104870
`9/2001
`95/13050
`5/1995
`98/10773
`3/1998
`2005/097067
`10/2005
`2007/106723
`9/2007
`2008/036847
`3/2008
`
`OTHER PUBLICATIONS
`
`Bruce eta!., Apr. 2001, "Zinc and the eye", Journal Of The American
`College of Nutrition, 106-118.
`Kabara eta!., 1997, Preservative-Free and Self-Preserving Cosmetics
`and Drugs-Principles and Practice, Chapter 1, pp. 1-14, Marcel
`Dekker, Inc.
`McCarthy eta!., 1989, "The Effect of Zinc Ions on the Antimicrobial
`Activity of Selected Preservatives", Journal of Pharmacy and Phar(cid:173)
`macology, vol. 41, 114P.
`McCarthy, 1985, "Metal Ions as Microbial Inhibitors", Cosmetic &
`Toiletries, 100:69-72.
`PCT International Search Report for corresponding International
`Application No. PCT/US2007/079082 with mailing date Apr. 7,
`2008.
`
`(Continued)
`
`Primary Examiner- Ernst V Arnold
`(74) Attorney, Agent, or Firm- Scott A. Chapple
`
`ABSTRACT
`(57)
`The present invention is directed to the provision of multi(cid:173)
`dose, self-preserved ophthalmic compositions. The composi(cid:173)
`tions possess sufficient antimicrobial activity to satisfY USP
`preservative efficacy requirements, as well as similar preser(cid:173)
`vative standards (e.g., EP and JP), without requiring the pres(cid:173)
`ence of conventional anti -microbial preservative agents, such
`as benzalkonium chloride. The compositions are effectively
`preserved by a balanced ionic buffer system containing zinc
`ions at a concentration of0.04 to 0.9 mM, preferably 0.04 to
`0.4 mM. One aspect of the balanced buffer system is limita(cid:173)
`tion of the amount of buffering anions present to a concen(cid:173)
`tration of 15 mM or less, preferably 5 mM or less. In a
`preferred embodiment, the compositions also contain borat
`or, most preferably, one or more borate/polyol complexes.
`The use of propylene glycol as the polyol in such complexes
`is strongly preferred. Limiting the amount of divalent metals
`other than zinc and the amount of ionized salts present has
`also been determined to be important to maximize the anti(cid:173)
`microbial activity of the balanced buffer systems.
`
`28 Claims, 3 Drawing Sheets
`
`Exhibit 1001
`ARGENTUM
`
`000001
`
`

`

`US 8,268,299 B2
`Page 2
`
`OTHER PUBLICATIONS
`
`PCT Written Opinion for corresponding International Application
`No. PCT/US2007 /079082 with mailing date Apr. 7, 2008,
`Zeelie et a!., 1992, "The Effects of Selected Metal Salts on the
`Microbial Activities of Agents used in the Pharmaceutical and
`Related Industries", Metal Compounds in Environment and Life,
`4:193-200.
`Zeelie et al., 1998, "Effects of copper and zinc ions on the germicidal
`properties of two popular pharmaceutical antiseptic agents
`cetylpyridinium chloride and povidone-iodine", Analyst, 123:503-
`507.
`U.S. Appl. No. 12/441,995 Office Action dated Sep. 16, 20ll.
`
`U.S. Appl. No. 12/441,742 Office Action dated Jul. 28, 2011.
`Guttman, "Liquid gel therapy broadens role of dry eye product line",
`Ophthalmologytimes.com, 2006, pp. 33-34 and copyright notice.
`HoffmanH.M. et al., "Pre-clinical in vitro Testing of an Artificial Tear
`Formulation with a Novel Preservation System", poster presentation
`at the annual meeting of the Association for Research In Vision And
`Opthalmology (ARVO), Ft. Lauderdale, FL, Apr. 30, 2006.
`Illustration of packaging for Systane® Free, Mar. 7, 2006.
`Systane® Free promotional document (minimal-blur) published on
`or about Jan. 1, 2006.
`* cited by examiner
`
`000002
`
`

`

`U.S. Patent
`
`Sep.18,2012
`
`Sheet 1 of 3
`
`US 8,268,299 B2
`
`FIG. 1
`
`25.0 - - - - - - - - - - - - - - - - - - - - - - - - - . ,
`
`~ 0.25% Boric Acid
`
`:
`i
`_..... 0.25% Propylene Glycol and 0.2.5% Boric Acid •
`'·
`
`..... ···: X 0.25% Mannitol and 0.25% Boric Acid
`i -e.- 0.25% Sorbitol and 0.25% Boric Acid
`
`>. ............... ·--------····································· ............................................
`
`t,
`/
`l
`I
`f.
`/
`~
`/x
`l·
`/
`r·
`~>
`lx
`l
`/t
`ll
`tl
`"' X
`l>t
`. ··········································;/l:···· ··········lt······
`
`"' .... /"'{·
`/X
`
`20.0
`
`m
`:i
`~ 15.0
`z
`z
`.....
`....
`0 ,...
`§ 10.0
`0
`~
`
`5.0
`
`/
`.ft
`. ·····························;,;.:0···
`A/ X
`.~·"'"'~
`. .a""/
`... ., •• , ... ~.~
`__ ,'>:'_.,/
`0.0 .__""""'_~;o;;;;;.;.>~_,~~-.,.,.,....~;;.,_------~----!
`7
`8
`4
`5
`9
`10
`pH
`
`····--·············-----··~~/'•••••
`
`d
`
`·.rc_,.
`
`ll
`~~
`t1-'
`i?
`~ff;
`
`000003
`
`

`

`U.S. Patent
`
`Sep.18,2012
`
`Sheet 2 of 3
`
`US 8,268,299 B2
`
`FIG. 2-
`
`30.0 - - - - - - - - - - - - - - - - - - - - - - - -....
`
`:!5.0
`
`-<111--0.25% Propylene Glycol and 0.25% Boric Acid
`
`--1.5% Propylene Giycol and 0.25% Boric Acid
`
`::K 0.25% M:a11nllol and 0.25% Boric Aci(j
`
`4
`
`5
`
`6
`
`7
`pH
`
`8
`
`g
`
`10
`
`000004
`
`

`

`U.S. Patent
`
`Sep.18,2012
`
`Sheet 3 of 3
`
`US 8,268,299 B2
`
`l"lG. J
`
`180.0
`
`i .. ~.1%s;;iic'A"CKii~·~ s0;:sii0i ..... ·····1
`160.0 · ...... ! --<&-1% 13ntic.l\cid and 0.25% Sorbitol
`
`; ··
`
`.............. ~
`
`40.0
`
`4
`
`5
`
`6
`
`pH
`
`7
`
`8
`
`9
`
`10
`
`000005
`
`

`

`US 8,268,299 B2
`
`1
`SELF PRESERVED AQUEOUS
`PHARMACEUTICAL COMPOSITIONS
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`The present application claims priority based on U.S. Pro(cid:173)
`visional Patent Application Ser. Nos. 60/827,411 filed Sep.
`28, 2006, and 60/826,529, filed Sep. 21, 2006.
`
`BACKGROUND OF THE INVENTION
`
`The present invention is directed to self-preserved pharma(cid:173)
`ceutical compositions. More specifically, the invention is
`directed to the provision of aqueous, multi-dose pharmaceu(cid:173)
`tical compositions that have been formulated so as to have
`sufficient antimicrobial activity to satisfY the preservation
`efficacy requirements of the United States Pharmacopeia
`("USP") and analogous guidelines in other countries, without 20
`requiring a conventional antimicrobial preservative, such as
`benzalkonium chloride, polyquaternium-1, hydrogen perox(cid:173)
`ide (e.g., sodium perborate), or chorine-containing agents.
`The ability to achieve self-preservation is based on a unique
`combination of formulation components and criteria.
`Many pharmaceutical compositions are required to be ster(cid:173)
`ile (i.e., free of bacteria, fungi and other pathogenic microor(cid:173)
`ganisms). Examples of such compositions include: solutions
`and suspensions that are injected into the bodies ofhumans or
`other mammals; creams, lotions, solutions or other prepara(cid:173)
`tions that are topically applied to wounds, abrasions, burns,
`rashes, surgical incisions, or other conditions where the skin
`is not intact; and various types of compositions that are
`applied either directly to the eye (e.g., artificial tears, irrigat(cid:173)
`ing solutions, and drug products), or are applied to devices
`that will come into contact with the eye (e.g., contact lenses).
`The foregoing types of compositions can be manufactured
`under sterile conditions via procedures that are well known to
`those skilled in the art. However, once the packaging for a
`product is opened, such that the composition contained 40
`therein is exposed to the atmosphere and other sources of
`potential microbial contamination (e.g., the hands of a human
`patient), the sterility of the product may be compromised.
`Such products are typically utilized multiple times by the
`patient, and are therefore frequently referred to as being of a 45
`"multi-dose" nature.
`Due to the frequent, repeated exposure of multi-dose prod(cid:173)
`ucts to the risk of microbial contamination, it is necessary to
`employ a means for preventing such contamination from
`occurring. The means employed may be: (i) a chemical agent 50
`that prevents the proliferation of microbes in a composition,
`which is referred to herein as an "antimicrobial preservative";
`or (ii) a packaging system that prevents or reduces the risk of
`microbes reaching a pharmaceutical composition within a
`container.
`Prior multi-dose ophthalmic compositions have generally
`contained one or more antimicrobial preservatives in order to
`prevent the proliferation of bacteria, fungi and other
`microbes. Such compositions may come into contact with the
`cornea either directly or indirectly. The cornea is particularly 60
`sensitive to exogenous chemical agents. Consequently, in
`order to minimize the potential for harmful effects on the
`cornea, it is preferable to use anti-microbial preservatives that
`are relatively non-toxic to the cornea, and to use such preser(cid:173)
`vatives at the lowest possible concentrations (i.e., the mini(cid:173)
`mum amounts required in order to perform their anti-micro(cid:173)
`bial functions).
`
`2
`Balancing the anti-microbial efficacy and potential toxico(cid:173)
`logical effects of anti-microbial preservatives is sometimes
`difficult to achieve. More specifically, the concentration of an
`antimicrobial agent necessary for the preservation of oph(cid:173)
`thalmic formulations from microbial contamination may cre(cid:173)
`ate the potential for toxicological effects on the cornea and/or
`other ophthalmic tissues. Using lower concentrations of the
`anti-microbial agents generally helps to reduce the potential
`for such toxicological effects, but the lower concentrations
`10 may be insufficient to achieve the required level of biocidal
`efficacy (i.e., antimicrobial preservation).
`The use of an inadequate level of antimicrobial preserva(cid:173)
`tion may create the potential for microbial contamination of
`15 the compositions and ophthalmic infections resulting from
`such contaminations. This is also a serious problem, since
`ophthalmic infections involving Pseudomonas aeruginosa or
`other virulent microorganisms can lead to loss of visual func-
`tion or even loss of the eye.
`Thus, there is a need for a means of enhancing the activity
`of anti-microbial agents so that very low concentrations of the
`agents can be utilized without increasing the potential for
`toxicological effects or subjecting patients to unacceptable
`risks of microbial contamination and resulting ophthalmic
`25 infections.
`Ophthalmic compositions are generally formulated as iso(cid:173)
`tonic, buffered solutions. One approach to enhancing the
`anti-microbial activity of such compositions is to include
`multi-functional components in the compositions. In addition
`30 to performing their primary functions, these multi-functional
`components also serve to enhance the overall anti-microbial
`activity of the compositions.
`The following publications may be referred to for further
`35 background regarding the use of multi-functional compo(cid:173)
`nents to enhance the antimicrobial activity of ophthalmic
`compositions:
`1. U.S. Pat. No. 5,817,277 (Mowrey-McKee, et a!;
`tromethamine);
`2. U.S. Pat. No. 6,503,497 (Chowhan, et a!.; borate/polyol
`complexes);
`3. U.S. Pat. No. 5,741,817 (Chowhan, eta!.; low molecular
`weight amino acids such as glycine);
`4. U.S. Pat. No. 6,319,464 (Asgharian; low molecular weight
`amino alcohols);
`5. U.S. Patent Application Publication No. US 2002/0122831
`A1 (Mowrey-McKee, eta!.; bis-aminopolyols);
`6. U.S. Pat. No. 6,348,190 (Illes, eta!.; zinc); and
`7. JP 2003-104870 (zinc).
`The use of zinc to enhance the antimicrobial activity of
`pharmaceutical compositions, including ophthalmic solu(cid:173)
`tions, is well known. See, for example, the following articles
`and patent publications, as well as U.S. Pat. No. 6,348,190
`and JP 2003-104870, cited above:
`55 McCarthy, "Metal Ions and Microbial Inhibitors", Cosmetic
`& Toiletries, 100:69-72 (February 1985);
`Zeelie, et a!., "The Effects of Selected Metal Salts on the
`Microbial Activities of Agents used in the Pharmaceutical
`and Related Industries", Metal Compounds in Environ(cid:173)
`ment and Life, 4:193-200 (1992);
`Zeelie, et a!., "Effects of Copper and Zinc Ions on the Ger(cid:173)
`micidal Properties of Two Popular Pharmaceutical Anti(cid:173)
`septic Agents, Cetylpyridinium Chloride and Povidone(cid:173)
`iodine", Analyst, 123:503-507 (March 1998);
`65 McCarthy, eta!., "The Effect of Zinc Ions on the Antimicro(cid:173)
`bial Activity of Selected Preservatives", Journal of Phar(cid:173)
`macy and Pharmacology, Vol. 41 (1989);
`
`000006
`
`

`

`US 8,268,299 B2
`
`3
`U.S. Pat. No. 6,482,799 (Tuse, eta!.);
`U.S. Pat. No. 5,320,843 (Raheja, eta!.);
`U.S. Pat. No. 5,221,664 (Berkowitz, eta!.);
`U.S. Pat. No. 6,034,043 (Fujiwara, eta!.);
`U.S. Pat. No. 4,522,806 (Muhlemann, eta!.);
`U.S. Pat. No. 6,017,861 (Fujiwara, eta!.); and
`U.S. Pat. No. 6,121,315 (Nair, eta!.).
`The present invention is directed to the provision of improved
`preservative systems containing zinc ions.
`The compositions of the present invention are multi-dose 10
`products that do not require a conventional antimicrobial
`preservative (e.g., benzalkonium chloride), and yet are pre(cid:173)
`served from microbial contamination. Such compositions
`have been referred to in the art as being "preservative free"
`(see, e.g., U.S. Pat. No. 5,597,559 issued to Olejnik, eta!.).
`Compositions that are preserved from microbial contamina(cid:173)
`tion as a result of the inherent antimicrobial activity of one or
`more components of the compositions are also referred to in
`the art as being "self-preserved" (see, e.g., U.S. Pat. No.
`6,492,361 issued to Muller, eta!.).
`The following publication may be referred to for further
`background regarding pharmaceutical compositions that are
`"preservative-free" or "self-preserving": Kabara, eta!., Pre(cid:173)
`servative-Free and Self-Preserving Cosmetics and Drugs(cid:173)
`Principles and Practice, Chapter 1, pages 1-14, Marcel Dek(cid:173)
`ker, Inc. (1997).
`The multi-dose compositions of the present invention,
`which do not contain a conventional antimicrobial preserva(cid:173)
`tive, are referred to herein as being "self-preserved".
`
`4
`Eye Drops, which is marketed by Alcon Laboratories, Inc.),
`or (ii) preserved by means of a so-called "disappearing" pre(cid:173)
`servatives, such as the chlorite-based system described in
`U.S. Pat. Nos. 5,424,078; 5,736,165; 6,024,954; and 5,858,
`346 (e.g., the artificial tears product "REFRESH™ Tears",
`which is marketed by Allergan), or the peroxide-containing
`system described in U.S. Pat. Nos. 5,607,698; 5,683,993;
`5,725,887; and 5,858,996 (e.g., the artificial tear product
`"GenTeal™ Tears", which is marketed by CIBA Vision).
`Unlike these existing products, the multi-dose ophthalmic
`compositions of the present invention are able to satisfY the
`USP preservative efficacy requirements, as well as analogous
`requirements in other countries, including the Japanese Phar(cid:173)
`macopoeia ("JP") and European Pharmacopoeia ("EP") pre-
`15 servative efficacy standards, without employing any conven(cid:173)
`tional antimicrobial preservatives, such as chlorite or
`hydrogen peroxide.
`The above-discussed findings regarding the zinc may be
`applied to enhance the antimicrobial activity of various types
`20 of pharmaceutical compositions. However, the present inven(cid:173)
`tion is particularly directed to the provision of aqueous oph(cid:173)
`thalmic solutions that are effective in preventing microbial
`contamination in the absence of conventional antimicrobial
`preservatives, such as benzalkonium chloride ("BAC"),
`25 polyquatemium-1, chlorite or hydrogen peroxide.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`SUMMARY OF THE INVENTION
`
`The present invention is directed to the self-preservation of
`aqueous ophthalmic compositions via the use of very low
`concentration of zinc ions. The present invention is based in 35
`part on the finding that in order to utilize low concentrations
`of zinc ions to self-preserve multi-dose ophthalmic compo(cid:173)
`sitions having ophthalmically acceptable pH and osmolality
`values, certain formulation parameters must be maintained.
`Specifically, the concentration of buffering anions utilized to 40
`maintain the pH within an ophthalmically acceptable range
`must be limited to an amount of 15 millimolar ("mM") or less
`in order to avoid interfering with the anti-microbial activity of
`the zinc ions.
`In addition, it has been determined that the antimicrobial 45
`activity of the zinc-containing compositions of the present
`invention can be further enhanced by the use of zinc ions in
`combination with borate or a borate/polyol complex, and that
`if such a combination is utilized, the use of propylene glycol
`is strongly preferred, so as to avoid ionic interactions between 50
`anionic species generated by otherpolyols (e.g., sorbitol) and
`the zinc cations.
`It has also been determined that the performance of the
`zinc-based preservative systems of the present invention is
`further enhanced by: (i) limiting the amount of multivalent 55
`metal cations other than zinc (e.g., calcium and magnesium)
`in the compositions of the present invention; and (ii) limiting
`the amount of ionized salts (e.g., sodium chloride and potas(cid:173)
`sium chloride) in said compositions. As described in greater
`detail below, the compositions of the present invention are 60
`preferably free of or substantially free of both ionized salts
`and multivalent metal cations other than zinc.
`The self-preserved, multi -dose compositions of the present
`invention have several advantages over existing ophthalmic
`formulations that are either: (i) packaged as a "single dose" or
`"unit of use" product, so as to avoid the inclusion of any
`antimicrobial preservative (e.g., BION®TEARS Lubricant
`
`FIG. 1 is a graph showing the amount of 1 N Sodium
`30 Hydroxide needed to adjust pH of 1 Kg solution ofBoricAcid
`(0.25%) in presence of mannitol, sorbitol or propylene glycol.
`FIG. 2 is a graph showing the amount of 1 N Sodium
`Hydroxide needed to adjust pH of 1 Kg solution ofBoricAcid
`(0.25%) in presence of propylene glycol.
`FIG. 3 is a graph showing the amount of 1 N Sodium
`Hydroxide needed to adjust pH of 1 Kg solution Boric Acid
`(1%) in presence of different concentrations of sorbitol.
`
`DETAILED DESCRIPTION OF THE INVENTION
`
`The pharmaceutical compositions of the present invention
`contain zinc ions at a concentration of0.04 to 0.9 millimoles/
`liter ("mM"), preferably 0.04 to 0.4 mM and most preferably
`0.1 to 0.4 mM. The use of this very low concentration is
`particularly desirable in ophthalmic pharmaceutical compo(cid:173)
`sitions containing therapeutically active agents, such as pros-
`taglandin analogues used to control intraocular pressure (e.g.,
`travoprost), because at higher concentrations the zinc ions
`may produce an astringent effect when applied to the eye. The
`zinc ions are preferably provided in the form of zinc chloride,
`at a concentration of 0.0005 to 0.012 percent by weight/
`volume ("w/v %"), preferably 0.0005 to 0.005 w/v % and
`most preferably 0.001 to 0.005 w/v %.
`The zinc may be provided in various forms, such as zinc
`chloride, zinc sulfate, zinc acetate or zinc carbonate. The use
`of zinc chloride is preferred.
`As indicated above, the present invention is based on part
`on a finding that anionic agents utilized to buffer the compo(cid:173)
`sitions of the present invention may interfere with the ability
`of zinc to exert antimicrobial activity. Such interference can
`be very detrimental to the ability of the compositions to
`maintain sufficient antimicrobial activity to meet preservative
`efficacy standards, particularly in view of the very low con(cid:173)
`centrations of zinc utilized in the present invention. Accord-
`65 ingly, it has been determined that the total concentration of
`anionic species in the compositions of the present invention
`should be limited. Specifically, it is preferred that the total
`
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`US 8,268,299 B2
`
`5
`concentration of anionic species, particularly buffering
`anions, should be limited to an amount of less than 15 mM,
`more preferably less than 10 mM, and most preferably less
`than 5 mM. For simplicity and clarity, the concentration of
`buffering anionic species in this patent application will be
`represented by the concentration of monovalent cations (such
`as sodium) that are present or needed to bring the pH to the
`specified value.
`As utilized herein, the phrase "less than" relative to a
`specified concentration (e.g., 15 mM) means that the speci(cid:173)
`fied component (e. g., buffering anions) is either not present in
`the composition at all or is present at a concentration less than
`the specified limit (e.g., 15 mM).
`It has been determined that multivalent buffering anions,
`particularly citrate and phosphate, have a significant adverse 15
`effect on the antimicrobial activity of the zinc-based preser(cid:173)
`vative systems described herein. The compositions of the
`present invention therefore preferably do not contain any
`multivalent buffering anions, other than borate-polyol com(cid:173)
`plexes, which may be multivalent under certain conditions
`(e.g., pH and/or borate:polyol ratio), or are substantially free
`of such buffering anions. As utilized herein, the phrase "sub(cid:173)
`stantially free of multivalent buffering anions" means that the
`composition either does not contain any multivalent buffering
`anions or contains an amount of said anions that does not
`inhibit the ability of the composition to satisfY specified pre(cid:173)
`servative efficacy standards (e.g., USP, EP or JP). The amount
`of multivalent buffering anions in the compositions of the
`present invention is preferably less than 5 mM, with said
`concentration being determined in the same manner as speci(cid:173)
`fied in the preceding paragraph.
`As indicated above, it has been determined that the antimi(cid:173)
`crobial activity of the zinc-based preservative systems of the
`present invention is also adversely affected by other divalent
`cations, such as calcium and magnesium. The antimicrobial
`activity of divalent zinc ions (Zn2+) is based upon the ability
`of the ions to competitively bind and inactivate macromolecu(cid:173)
`lar complexes that are critical to the central metabolic activity
`of the prokaryotic cell. In order for Zn to kill, it must first gain
`access to the cytoplasm and its charge density prevents its
`diffusion across the membrane at a physiologically signifi(cid:173)
`cant rate. Therefore, the ability of Zn2
`+ ions to enter the cell
`must be facilitated by membrane transport proteins. Access to
`these transport proteins can be competitively inhibited by
`multivalent metal cations, particularly Mg2+, Ca2+, Mn2+,
`Ni 2
`+, and Co 2
`+. Thus, increasing the extracellular concentra(cid:173)
`tion of these inhibitory cations diminishes the capacity of
`Zn2
`+ ions to gain access to the cytoplasm and subsequently
`reduces its cytotoxic activity to the microorganism.
`In view of the potential interference of multivalent metal
`cations other than zinc, the compositions of the present inven(cid:173)
`tion preferably do not contain such cations or are substan(cid:173)
`tially free of said cations. As utilized herein, the phrase "sub(cid:173)
`stantially free of multivalent metal cations other than zinc"
`means that the composition either does not contain such cat(cid:173)
`ions or contains an amount of said cations that does not inhibit
`the ability of the composition to satisfy specified preservative
`efficacy standards (e.g., USP, EP or JP). The amount of mul(cid:173)
`tivalent metal cations other than zinc in the compositions of
`the present invention is preferably less than 5 mM.
`It has also been determined that ionized salts (e.g., sodium
`chloride and potassium chloride) adversely affect the antimi(cid:173)
`crobial activity of the preservative systems described herein.
`Accordingly, the compositions of the present invention pref(cid:173)
`erably do not contain ionized salts, or are substantially free of
`ionized salts. As utilized herein, the phrase "substantially free
`of ionized salts" means that the composition either does not
`
`6
`contain any ionized salt or contains an amount of ionized salt
`that does not inhibit the ability of the composition to satisfy
`specified efficacy standards (e.g., USP, JP or EP). The amount
`of ionized salt contained in the compositions of the present
`invention is preferably less than 50 mM.
`As used herein, the term "borate" includes boric acid,
`sodium borate and potassium borate. The use ofborates con(cid:173)
`taining divalent cations (e.g., calcium borate) may adversely
`affect the antimicrobial action of zinc ions, by competing
`10 with zinc for binding sites on the cell walls of bacterial and
`other microbes, and is therefore should be avoided. For the
`same reason, the self-preserved compositions of the present
`invention are preferably free of or substantially free of other
`sources of divalent cations, such as calcium chloride.
`The self-preserved compositions of the present invention
`preferably contain one or more borates in an amount of from
`about0.1 toabout2.0%w/v, morepreferably0.3 to 1.5%w/v,
`and most preferably 0.5 to 1.2% w/v.
`As used herein, the term "polyol" includes any compound
`20 having at least one hydroxyl group on each of two adjacent
`carbon atoms that are not in trans configuration relative to
`each other. The polyols can be linear or cyclic, substituted or
`unsubstituted, or mixtures thereof, so long as the resultant
`complex is water soluble and pharmaceutically acceptable.
`25 Examples of such compounds include: sugars, sugar alco(cid:173)
`hols, sugar acids and uronic acids. Preferred polyols are sug(cid:173)
`ars, sugar alcohols and sugar acids, including, but not limited
`to: marmitol, glycerin, xylitol, sorbitol and propylene glycol.
`As indicated above, the use of propylene glycol is particu-
`30 larly preferred in order to limit the presence of anionic spe(cid:173)
`cies. Boric acid interacts with polyols, such as glycerol, pro(cid:173)
`pylene glycol, sorbitol and marmitol, to form borate polyol
`complexes. The type and ratio of such complexes depends on
`the number of OH groups of a polyol on adjacent carbon
`35 atoms that are not in trans configuration relative to each other.
`For example, propylene glycol has only one OH group on
`each of two adjacent carbon atoms that are not in trans con(cid:173)
`figuration. Consequently, one molecule of boric acid will
`interact and form a complex with one or two molecules of
`40 propylene glycol, resulting in a monovalent anion. However,
`in the case of sorbitol, mannitol and other sugar-type polyols,
`this interaction is much more complex, because one molecule
`of such polyols can complex with two molecules of borate
`and then further complex with two additional molecules of
`45 the polyol, resulting in a multivalent anion.
`When borate is present in the compositions of the present
`invention, the compositions preferably also contain one or
`more polyols, at a total concentration of0.25 to 2.5% w/v. The
`polyol preferably is propylene glycol at a concentration of
`50 0.25 to 1.80% w/v, preferably 0.25 to 1.25% w/v. Although
`less preferable than propylene glycol, sorbitol and mannitol
`are also preferred polyols, and preferably are used at a con(cid:173)
`centration of0.05 to 0.75% w/v, preferably 0.05 to 0.5% w/v.
`The compositions of the present invention preferably con-
`55 tain borate or a borate/polyol complex, most preferably a
`borate/polyol complex wherein thepolyol portion of the com(cid:173)
`plex is propylene glycol or a combination of propylene glycol
`and sorbitol. The preference for propylene glycol is based on
`a discovery that sorbitol and other polyols have a greater
`60 tendency to form anionic species at pH values of7.5 or less,
`and that such anionic species may interfere with the antimi(cid:173)
`crobial activity of zinc. The graphs shown in FIGS.l-3 dem(cid:173)
`onstrate that sorbitol has a much higher tendency to form
`anionic species in the presence of boric acid, compared to
`65 propylene glycol.
`The data shown in FIGS. 1-3 were compiled as follows: A
`1 Kg solution containing the given concentrations of boric
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`US 8,268,299 B2
`
`7
`acid and propylene glycol or sorbitol or mannitol was pre(cid:173)
`pared and the initial pH of the solution was determined. 1 N
`NaOH was then added to adjust the pH. The cumulative
`amount of sodium hydroxide used to adjust pH to different
`values was then recorded.
`As explained above, boric acid interacts and forms an ionic
`complex with species containing several hydroxyl groups,
`such as mannitol and sorbitol. However, the interaction
`between boric acid and propylene glycol is more limited than
`with other polyols. This is represented by the amount of
`sodium hydroxide needed to adjust pH, as shown in FIG. 1.
`Sorbitol and mannitol significantly shift the curve relative to
`the amount ofNaOH required to lower pH, whereas propy(cid:173)
`lene glycol only slightly shifts the curve. This is further evi(cid:173)
`dent in FIG. 2.
`The present invention is particularly directed to the provi(cid:173)
`sion of multi-dose, self-preserved ophthalmic compositions
`that have sufficient antimicrobial activity to allow the com(cid:173)
`positions to satisfy the USP preservative efficacy require(cid:173)
`ments, as well as other preservative efficacy standards for
`aqueous pharmaceutical compositions, without a conven(cid:173)
`tional antimicrobial preservative.
`The preservative efficacy standards for multi-dose oph(cid:173)
`thalmic solutions in the U.S. and other countries/regions are
`set forth in the following table:
`
`Preservative Efficacy Test ("PET") Criteria (Log
`Order Reduction of Microbial Inoculum Over Time
`
`Bacteria
`
`Fungi
`
`USP 27
`
`A reduction of 1 log (90%),
`by day 7; 3 logs (99.9%) by
`day 14; and no increase after
`day 14
`
`Japan
`
`Ph. Eur.A 1
`
`Ph. Eur. B
`
`FDA/ISO
`14730
`
`3 logs by 14 days; and no
`increase from day 14
`through day 28.
`A reduction of2logs (99%)
`by 6 hours; 3 logs by 24
`hours; and no recovery afte