GB2129685A - Anti-haemophilic compositions - Google Patents

Abstract

An intravenous anti-haemophilic pharmaceutical composition contains a mixture of phospholipid and Factor VIII in a ratio of at least 2.5 mu g of phospholipid per international unit of Factor VIII. The phospholipid in the mixture must contain at least 15% of phosphatidyl serine (PS). The composition may be prepared by dispersing PS-rich phoshpolipid in an aqueous solution to afford an emulsion and then incubating the phospholipid emulsion with Factor VIII. Freeze-drying the phospholipid/Factor VIII mixture obtained gives a composition in a form convenient for medical use.

Description

SPECIFICATION Anti-haemophilic pharmaceutical composition The present invention relates to an anti-haemophilic pharamceutical composition and to a process for the preparation thereof.

Although the treatment of haemophilia patients with Factor VIII concentrates is nowfairly uncomplicated, a small number of patients (estimated at about 10% of all haemophiliacs) develop antibodies to Factor VIII. These patients become unresponsive to normal doses of FactorVIII and theirtreatment is a major clinical problem. Although very high doses of FactorVlli are sometimes effective, the effect is only short-lived and the treatment is very expensive.

Thereisthereforea need for an improved method ofhaemophiliatreatmentwhich is applicable to at least some of these patients.

It is one object ofthe present invention to provide anti-haemophilic pharmaceutical composition in which FactorVIII is protected against attack by antibodies and which may therefore form the basis of such an improved method oftreatment.

It is a further object ofthe present invention to provide a process for the preparation of an antihaemophilic pharmaceutical composition in which Factor VIII is protected against attack by anti-bodies.

Other objects and advantages ofthe present invention will become apparentfrom thefollowing description thereof.

According to the present invention there is provided an anti-haemophilic pharmaceutical composition for intravenous administration comprising a mixture of phospholipid and Factor VIII in a ratio of at least 2.5 pg of phospholipid per international unit of FactorVIII wherein the phospholipid in the mixture contains at least 15% (byweight) of phosphatidyl serine.

In the present specification an international unit (iu) of FactorVIII is as defined bythe International StandardforFactorVlllasestablishedbyWHO (WHO Technical Report Series 626, 1978, page 17).

Generallywhen the present pharmaceutical composition is to be administered to a patient the phospholipid/FactorVIll mixture will be in conjunction with a pharmaceutically acceptable diluent or carrier.

Preferablythe ratio of phospholipid to FactorVIII in the mixture is between 2.5 and 250 pg per iu, especially20 and 250 pg per iu,whilstthe level of phosphatidyl serine (PS) in the phospholipid is between 15% and 50%, especially 20% and 50% (by weight).

In general the non-PS part ofthe phospholipid will consist predominantly of phosphatidyl choline (PC), phosphatidyl ethanolamine (PE) and/or phosphatidyl inositol (PI). In a particularly preferred embodiment of the present invention the phospholipid in the mixture will contain at least 10%, especially between 15% and 50%, (by weight) of PC.

The FactorVIII may be obtained from any suitable source. In a preferred embodimentofthepresent invention the composition contains porcine Factor VIII. In order to inactivate viruses that may be present, the Factor VIII preparation may be heattreated prior to the addition ofFactorVlllto phospholipid.Alternativelythe inactivation may be performed by the heat treatment ofthe phospholipid/Factor VIII mixture.

The present composition may also contain (in addition to the Factor VIII and phospholipid)further non-toxic materials, especially naturally occuring materials. Thesefurther materials are generally derived from plasma or phospholipid rich tissues sources and are extracted from these substances together with, respectively, Factor VIII or phosphilipid. Typical of these materials is fibrinogen and albumin.

Preferably the pharmaceutically acceptable diluent or carrier is water. However this may be replaced by other suitable diluents or carriers, eg. physiological salt solution, if medical circumstances so dictate.

The present composition may be provided for medical use (ie inthetreatmentof haemophilia) in reagentkitform. In one embodiment of such a reagent kit, the Factor VIII, generally in theform of a plasma fraction which also contains materials such asfibrinogen and albumin, is freeze dried,whilstthe phospholipid is dispersed in an aqueous solution (preferably water or saline to form a dispersion in which 15% (byweight) ofthe phospholipid dispersed is phosphotidyl serine.In orderto preparethe composition from these ingredients the freeze dried FactorVIII is addedtothe phospholipid emuision. In an alternative and preferred embodiment of the present reagent kit, a Factor VIll/phospholipid mixture, according to the present invention, together with any associated materials, such asfibrinogen and albumin, is freeze dried. In this case the present composition is prepared by adding the freeze dried mixture to an aqueous solution (generally water or saline). In each of these cases the kit may also comprise a sample of pharmaceutically acceptable waterorsaline, as well as a set of instructions designed to facilitate the formulation of the composition from the kit's ingredients.

The advantage ofthe present composition over previous Factor VIII compositions is that, in the presentcase,the Factor VIII is protected against attack by antibodies. This protection against inactivation, although not a long-term effect, lasts long enough to allowthe successful treatment of those haemophilia patients that develop anti-bodies to FactorVIII. In other words, an in vivo injection ofthe present Factor VIll/phospholipid compositiongener- ates sufficientthrombin in the firstfew minutes after injection to provide a haemostatic effect.

This protection is a direct resultofthe relatively high levels of PS that are required in the present FactorVIll/phospholipid mixture. Factor VIII composi tionsthat do not contain such levels of PS do not appearto offer a similar protection against antibody attack. The present inventors believe, although the invention is not in anyway limited by this explanation, that PS binding is an important part of the procoagulantactivity of FactorVIII and that human antibodies are directed against an antigenic site which is either identical or closely related to the PS binding site. It follows that PS effectively blocks the attack by antibody against Factor VIII.The effect of PS on VIII C: Ag assays (vide infra) provides strong evidenceforthis explanation.

The present composition may be prepared by any method that affords a Factor Vlll/phospholipid mix ture in which the ratio of phospholipid to Factor VIII in the mixture is at least 2.5 ug of phospholipid per iu of FactorVIII and inwhichthephospholipid in the mixture contains at least 15% (byweight) of PS.

However in a further aspect ofthe present invention there is provided a preferred process for the preparation of an anti-haemophilic pharmaceutical composition for intravenous administration which comprises dispersing phospholipid containing at least 15% (by weight) of phosphatidyl serine in an aqueous solution to afford a phospholipid emulsion and incubating the emulsion with Factor VIII to form a Factor VIlli phospholipid mixture with the proviso that the ratio of phospholipid to FactorVIII in the mixture is at least 2.5 ug of phospholipid per international unit of Factor VIII.

Preferablythe ratio of phospholipid in the emulsion to Factor VIII is between 2.5 and 250 jig per iu, especially 20 and 250 jig per iu, whilstthe level of PS in the phospholipid is between 15% and 50%, especiaily 20% and 50% (by weight).

The phospholipid that is dispersed in the aqueous solution may consist of purified or synthetic PS either alone or in admixture with other materials, such as phosphatidyl choline, phosphatidyl ethanol and phosphatidyl inositol, that are suitable ingredientsfor an anti-haemophilicpharmaceutical composition.

Although a phospholipid prepared in this manner is perfectly adequate for present purposes, in a preferred embodiment ofthe present invention the phospholipid is extracted, using a non-polar solvent, from a human, animal or planttissuethat is rich in PS.

Suitabletissuesources include bovine, human, porcine or rabbit brain, placenta, spinal cord, plasma or platelets, with bovine or human brain being a particularly good source of phospholipid that is rich in PS. An example of a suitable plant tissue source is the soya bean.

Any non-polar solvent that yields, on extraction of thetissue, phospholipid with the required level of PS may be employed in the above preferred process.

Suitable solvents includethe chlorinated alkanes, such as chloroform and dichloromethane, and petroleum ether (fractions 40 - 60, 60 - 80 and 80 - 100), with petroleum ether 40 - 60 being particularly preferred. This particularly preferred solvent (petroleum ether40 - 60) was used to good effect by J Floch (J Biol Chem, 1942, 146,35) to extract phospho- lipid, rich in PS, from brain cephalin, and the present inventors have now found that this method of extraction (with minor modifications) is particularly appropriate for the extraction of high levels of PS from tissue sources.

Whatever the choice of extraction solvent and method of extraction it is preferred ifthe phospholipid obtained is a stable product and contains a minimum of oxidation products. This can best be achieved by incorporating a suitable anti-oxidant, in particular butylated hydroxyanisole, into the solvent or solvents employed.

Once the phospholipid has been obtained by, for example, mixing purified or synthetic phospholipid or extracting these materials from natural sources, it (the phospholipid) is then dispersed in an aqueous solution by any ofthe emulsification methods that are weil known in this art. For example the phospholipid may be dissolved in methanol or ethanol, and then evaporation of most or all ofthe solvent followed by addition ofthe solid to water or physiological saline with vigorous mixing affords a phospholipid emulsion. Alternatively and preferably the phospholipid in powdered form may be dispersed in water or saline by ultrasonication.

The FactorVlllto be used in the present process will generally be in theform of a plasma fraction which also contains other protein materials such asfibrinogen and albumin. Such a Factor VIII preparation can readily be prepared by any ofthe isolation techniques that are well known intheart, seefor example "Human Blood Coagulation, Haemostasis and Thrombosis", Ed R Biggs,2nd Edn, 1976, Blackwell Scientific Publications, Chapter 11. In one particularly preferred imbodiment of the present process howeverafreeze dried intermediate purity preparation of FactorVIll is employed, said preparation being prepared bythe method described byJ Newman et al in The British Journal of Haematology, 1971,21,1.

As mentioned above, the Factor VIII preparation may be subjected to heattreatment, prior to its addition to phopholipid, in orderto inactivate viruses.

Alternatively,thephospholipid mayfirstbeaddedto the Factor VIII preparation, and the mixture maythen be subjected to said heattreatment.

In a preferred embodiment ofthe present invention, porcine Factor VIII is mixed with phospholipid.

The incubation time and temperature must, in each case, be sufficientto allowthe formation of a Factor Vlll/phospholipid mixture in which the FactorVIII is protected against inactivation by anti-bodies. Whilst very short or very long reaction times may be employed it is preferred to incubate the phospholipid emulsion with the Factor VIII for between 5 and 60 mins. Similarly a moderate incubation temperature, generally between 10 and 40 C, is preferred since below that range the complexing of Factor VEIL, with phospholipid (in particular PS) will be rather slow whilst above that rangethe materials present in the phospholipid emulsion and/or FactorVIII preparation will tend to denature.

The present anti-haemophilic pharmaceutical composition and processes for its preparation will now be described byway of example only.

Materials and Methods (A) Factor VIII preparation An intermediate purity Factor VIII was prepared by the method of J Newman etal, British Journal of Haematology, 1971,21,1.

(B) i. Preparation ofphospholipidbyextraction of human brain Human brain was obtained at postmortem within two days of death. The meninges and blood clots were removed from the brain, which wasthen washed in ice-cold 0.1 so NaCI, sliced into small pieces and weighed. The brain was homogenised for 2 minx with 1 vol of cold acetone, transferred to a Buchnerfunnel and filtered. The residue was extractedthreetimeswith 1 vol of cold acetone.The filtration was continued until the residue was just moist The phospholipid wasthen extracted from the acetone dried powder according to the method of J Folch etal, J Biol Chem, 1942, 146, 35, modified by shortening the drying time ofthe residue from acetone extractions, omitting overnight storage of the ethereal extract, and incorporating an antioxidant (butylated hydroxyanisol (BHA) concentration 1 gm litre~') in all solvents.

The fresh acetone-dried powder ways extracted with 1 vol (1 ml gm brain tissue) of petroleum ether (40 60 C) for 10 min, using vigorous shaking, and filtered through a Whatman (Trade Mark) No 1 filter paper.

The filtrate was dried in vacuo at30 C, using a rotary evaporator. The extractwasthen re-dissolved in 50 ml diethyl ether,filtered, and 250 ml cold acetone added. The mixture was filtered and the precipitate washed with cold acetone, then immediately dried in vacuo in the dark. The dried material was stored in sealed ampoules containing dry nitrogen, at -200C in the dark.

For use as a reagent. 5g ofthe extractwas emulsified by ultrasonication in 500 ml distilled water containing 0.1 mmol litre BHA. The emulsion was then distributed into amber glass ampoules containing 1 ml per ampoule (ie 10 mg phospholipid) and freeze dried underconditions described by PJ Campbell in JBioI Stand, 1974,2,249. The ampoules (coded 76/521) were sealed under dry nitrogen and stored at -200C.

The composition of phospholipid 76/521 was determined bytlcon pre-coated Kiesel gel 60 F254 plates (solvent system; CHCl3, MeOH, N H3: 75, 25, 3) and is given in Table I.

ii. Preparation ofphospholipid by extraction of animal brain The process (B)i above was repeated except that bovine brain replaced human brain. The ampoules of extracted phospholipid were coded 79/508.

The composition of phospholipid 79/508 was determined by tic as described in (B)i above and is given in Table I.

(C) Preparation of phospholipid from pure starting materials A number of phospholipids were prepared from pure smaples (synthetic or derived from tissue sources) of one or more of phosphatidyl serine (PS), phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE). The compositions of these phospholipids are given in Table I. They were each emulsified by untrasonication in the manner described in (B)i above.

(D) Commercialphospholipids A number of commercial phospholipids were employed for purposes of comparison. The phospholipids were Intralipid (Trade Mark, Kabi-Vitrum), Fibraccel (Trade Mark, Behring) and Tachostyptan (Trade Mark, Consolidated Chemicals).

The composition of each of these materials was determined by tic (as described in (B)i above) and is given in Table I.

(E) Haemophilic inhibitorplasmas These were obtained from the Royal Free Hospital, London and from the University Hospital of Wales, Cardiff. The inhibitortitre of each plasma is given in Bethesda Units.

TS33IE I Oom;sftions of Phospholipias method of Phospholipid code Pseparation or Trade Name PS m PC IS Sphingomeyelin Others Bi 76/521 41(a) 2(a) 17(a) 32(a) 8(a) 3 li 79/508 25(b) 1(b) 22(b) 30(b) 22(b) c i 100(b) c ii 100(e) e iii 100(d) c iv 100(e) Ov tOO(f) cvi 100(c) cvii 100(d) cviu 5(c) 95(c) e inc 10(c) 90(c) C x 20(c) 80(c) 0 xi 50(c) 50(c) Di Intralipid 100(e) Dii Fibraccel 9(g) 9(g) 38(g) 18(g) 14(g) 12(g) Diii Tacbostyptan 7(b) 30(b) 63(b) Notes: Tissue Sources - a, Buman Brain b, Bovine Brain c, Bovine Spinal Cord d, Synthetic e, Egg yolk f, Soya bean g, Placenta Example 1. Preparation ofan anti-haemophilic phar maceutical composition from Factor VIII and human brain phospholipid (76/521) A FactorVIII preparation (1 ml, 1.0 iu ml1), prepared according to Process A above, was incu bated at37 Cfor20 minutes with a phospholipid emulsion (1 ml, 0.2 mg ml-1), prepared according to process B i above. The incubate was then freeze dried and stored in a sealed ampoule under a nitrogen atmosphere at -20"C.

Example 2. Preparation of an anti-haemophilic phar- maceutical composition from Factor VIII and bovine brain phospholipid (79/508) The process of Example 1 was repeated except that bovine brain phospholipid prepared according to process B ii above replaced human brain phospholipid.

Example 3. Preparation of anti-haemophilicphar- maceutical composition from Factor VIII and bovine brain phosphatidyl serine The process of Example 1 was repeated except that (i) bovine brain phosphatidyl serine, obtained in purified form from natural sources, replaced human brain phospholipid, and (ii)the phospholipid emulsion was prepared by the process Ci,to afford a concentration of 0.2 mg ml ' of phospholipid.

Example 4 - 21. Preparation of an anti-haemophilic pharmaceutical composition from Factor VIII and pure samples of one or more phosphatides The process of Example 1 was repeated except that (i) human brain phospholipid was replaced by a series of phospholipid compositions, each compositions being preparedfrom pure samples of one or more phosphatides, (ii) the phospholipid was prepared by one of processes Cii - Cxi, and (iii) the ratio of phospholipid to FactorVIII in the pharmaceutical composition was set at 2.5, 20, 200 or 250 jig per iu.

Examples 22 - 24. Preparation of an anti-haemophilic pharmaceutical composition from Factor VIII and commerciallyavailable phospholipids The process of Example 1 was repeated exceptthat various commercilly available phospholipids replaced human brain phospholipid.

Example 25. Preparation of an anti-haemophilic pharmaceutical composition from heat treated Factor VIII and human brain phospholipid (76/521) The process of example 1 was repeated, except that the freeze dried FactorVIII preparation was heated at 60OCfor2-5 days priorto the addition of phospholipid.

Example 26. Preparation ofa heat treated antihaemophilic pharmaceutical composition from Factor VIII and human brain phospholipid (76/521) The process of Example 1 was repeated, except that priorto storage in a sealed ampoule the freeze dried mixture was heated at 60 C for 2 - 5 days.

The ratio of phospholipidto FactorVIII in the pharmaceutical compositions of Examples 1 to 26 is given in Table II.

Example Nethod of Phospholipid % PS Ratio of Phospolipid Preparation Table I) (2t) wt) to Factor VIII in Pharmaceutical Composition (y/iu) 1 3 i (76/521) 41 200 2 Bii. (79/508) 25 200 3 C i 100 200 4 cFi 100 2.5 5 C ii 100 200 6 C ii 100 250 7 (Comparative) C iii 0 200 8 (Comparative) C iv 0 200 g (Comparative) C v 0 20 10 (Comparative) C vi 0 2.5 11 (Comparative) C vi 0 20 12 (Comparative) C vi 0 250 13 (Comparative) C vii 0 200 14 (Comparative) C viii 5 2.5 15 (Comparative) C viii 5 250 16 (Comparative) C ix 10 2.5 17 (Comparative) C ix 10 250 18 e x 20 2.5 19 C x 20 250 20 a xi 50 2.5 21 C xi 50 250 22 (Comparative) Di 0 200 23 (Comparative) Dii 9 200 24 (Comparative) Diii 7 200 25 Bi 41 200 26 Bi 41 200 (F) Effect ofphospholipid on the level of Factor VIII clotting antigen Assaysfor FactorVIII clotting antigen were performed using a fluid phase immunoradiometric assay modified from the method of J Lazarchick etal, J Clin Invest, 1978,62,1048. Samples were incubated with labelled antibodyfor 4 hr at375C before precipitation of complexes with ammonium sulphate. Two antibodies were used, both isolated from haemophiliacs who had spontaneously developed inhibitors to FactorVIII C. CC 8000 (8000 BU/ml) was a gift from Dr E G DTuddenham (The Royal Free Hospital, London), while the other anitbody (1000 BU/ml) was kindly supplied by Dr I R Peake (University Hospital of Wales, Cardiff).

Prior to its addition to the test system, Factor VIII and the phospholipid (1:1, v/v) were incubated at 370for20 min. In control experiments, Factor VIII alone was incubated for 20 min at37 C, and the phospholipid was added afterthe addition of antibody.

The results ofthese assays are given in Table lil.

The reduction of Factor VIII clotting antigen detected in the presence ofvarious phosphilipids indicates the extent of protection of Factor VIII from antibody attack.

TA: E III Residual VIII C: Ag (%) after ileubation of Factor VIII with various phospholipids Equivalent Pharmaceutical % (by wt) Ratio of Phospholipid to Residual Composition (Table II) PS PC PE Factor VIII (ly Per iu) VIII C:Ag (%) 7 0 100 0 200 100 8 0 100 0 200 90 9 0 100 0 20 85 10 0 100 0 2.5 98 11 0 100 0 20 91 12 0 100 0 250 102 22 0 100 0 200 100 13 0 0 100 200 100 14 5 95 0 2.5 110 15 5 95 0 250 94 24 7 30 0 200 60 23 9 38 18 200 100 16 10 90 0 2.5 95 17 10 90 0 250 100 18 20 80 0 2.5 76 19 20 80 0 250 45 2 25 22 30 200 39 1 41 17 32 200 50 20 50 50 2.5 69 21 50 50 0 250 37 TABLE III (Oontd) Equivalent pharmaceutical % (by wt) Ratio of Phospholipid to Residual Composition (Table II) PS PC PE Factor VIII (11g per iu) VIII C: Ag (%) 3 100 0 0 200 30 4 100 0 0 2.5 49 5 100 0 0 200 37 6 100 0 0 250 35

Claims (24)

1. An anti-hairmophilic pharmaceutical composition for intravenous administration comprising a mixture of phospholipid and Factor VIII in a ratio of at least 2.5 jig of phospholipid per international unit of Factor VIII wherein the phospholipid in the mixture contains at least 15% (by weight) of phosphatidy Iserine.

2. Acomposition according to claim 1 wherein the ratio of phospholipid to Factor VIII in the mixture is between 20 and 250 jig per iu.

3. Acomposition according to either claim 1 or claim 2 wherein the phospholipid in the mixture contains between 20% and 50% (by weight) of phosphatidyl serine.

4. A composition according to any one of claims 1 to3whereinthephospholipid in the mixture also contains at least 10% (byweight) of phosphatidyl choline.

5. A composition according to claim 4 wherein the phospholipid in the mixture contains between 15% and 50% (by weight) of phosphatidyl choline.

6. A composition according to any one of claims 1 to Swherein the phospholipid in the mixture also contains phosphatidyl ethanolamine.

7. A composition according to any one of claims 1 to 6 wherein the phospholipid in the mixture also contains phosphatidyl inositol.

8. Acomposition according to any one of claims 1 to 7 wherein the Factor VIII is porcine FactorVIII.

9. A composition according to any one of claims 1 to 8 further comprising fibrinogen and albumin.

10. A composition according to any one of claims 1 to 9wherein the Factor VIII preparation has, priorto mixing with the phospholipid, been heat treated to inactivate viruses.

11. A composition according to any one of claims 1 to 9 wherein the mixture of phospholipid and Factor VIII is heat treated to inactivate viruses.

12. An anti-haemophilic pharmaceutical composition for intrav5enous administration according to claim 1 substantially as hereinbefore described with particular reference to anyoneof Examples 1 to 6,18 to 21 and 25 to 26.

13. Areagentkittofacilitatethe intravenous administration of an anti-haemophilic pharmaceutical composition according to claim 1, comprises freeze ..

dried Factor VIII, and an aqueous dispersion of a phospholipid, wherein the phospholipid in the dispersion contains at least 15% (by weight) of phosphatidyl serine.

14. A reagent kit according to claim 13wherein the Factor VIII is in the form of a plasma fraction.

15. A reagent kitto facilitate the intravenous administration of an anti-haemophilic pharmaceutical composition according to claim 1 comprises a freeze dried mixture of phospholipid and Factor VII I, wherein the ratio of phospholipid to Factor VIII in the mixture is at least 2.5 jig of phospholipid per international unit of Factor VIII and furtherwherein the phospholipid in the mixture contains at least 15% (by weight) of phosphatidyl serine.

16. A reagent kitto facilitate the intravenous administration of an anti-haemophilic pharmaceutical composition according to claim 1 substantially as hereinbefore described.

17. Aprocessforthe preparation of an antihaemophilic pharmaceutical composition for intravenous administration according to claim 1 comprises dispersing phospholipid containing at least 15% (by weight) of phosphatidyl serine in an aqueous solution to afford a phospholipid emulsion and incubating the emulsion with Factor VIII to form a FactorVIII/phospholipid mixture with the proviso that the ratio of phospholipid to Factor VIII in the mixture is at least 2.5 jig of phospholipid per international unit of Factor VIII.

18. A process according to claim 17 further comprising, priorto the dispersion ofthe phospholipid in the aqueous solution, extracting the phospholipid with a non-polar solventfrom a human, animal or plant tissue that is rich in phosphatidyl serine.

19. A process according to claim 18 wherein the tissue comprises bovine or human brain tissue.

20. A process according to either claim 18 or claim 19 wherein the non-polar solvent comprises petroleum either 40 - 60.

21. A process according to any one of claims 17 to 20 wherein an anti-oxidant is dissolved in the non-polarsovent.

22. A process according to claim 21 whereinthe anti-oxidantcomprises butylated hydroxanisole.

23. A process according to any one of claims 17 to 22 wherein the Factor VIII is in the form of a freeze dried intermediate purity preparation of Factor VIII.

24. A processforthe preparation of an antihaemophilic pharmaceutical composition for intravenous administration according to claim 1 substantially as hereinbefore described with particular referenceto any one of Examples 1 to 6, 18to21 and 25to 26.