AU616502B2 - Treatment of inflammatory disorders in humans - Google Patents

Description

R.K. MADDERN ASSOCIATES R C R.S. CATT THE COMMISSIONER OF PATENTS, CANBERRA, A.C.T.

LE-uT -iuT-uy -r It ili-l 616502 Form COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-62 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Class Int. Class Related Art: TO BE COMPLETED BY APPLICANT MEDVET SCIENCE PTY. LTD. Name of Applicant: Address of Applicant: Actual Inventor: AddresS for Service: care of Institute of Medical and Veterinary Science, Frome Road, Adelaide, State of South Australia, Commonwealth of Australia DR MICHAEL WELLESLEY WHITEHOUSE Care of R.K. MADDERN ASSOCIATES, 345 King William Street, Adelaide, South Australia Complete Specification for the invention entitled: "TREATMENT OF INFLAMMATORY DISORDERS IN HUMANS" The following statement is a full description of this invention, including the best method of performing it known to me.us.

aeciarant(s). U (Note: No attestation or other signature is re- 1 quired).

To: The Commissioner of Patents, Commonwealth of Australia.

R. K. MADDERN and ASSOCIATES, Citicorp House 345 King William Street, Adelaide, South Australia 5000.

FD 419-0 IM 9/85 This invention relates to the treatment of inflammatory disorders in the field of human medicine, and in particular concerns the treatment of systemic chronic inflammatory disease such as rheumatoid arthritis and local dermal persistent irritations for example psoriasis, using zinc salts of polyunsaturated fatty acids (PUFA), or cyclic derivatives thereof, such as prostanoic acid, prostenoic acids and prostaglandins.

The Applicants are aware of certain prior art literature which relates to the use of linoleic acid, and S-linolenic acid, and derivatives thereof for the treatment of various diseases and disorders in the field of human medicine and also to pharmaceutical and dietary compositions containing S the aforesaid substances for use therein. In this regard, reference is made to U.S. Patent Specification Nos. 4273763 (Horrobin), 4309415 (Horrobin), 4393049 (Horrobin) and 4444755 (Horrobin). Whilst certain of these patents also disclose the use of zinc in combination with X-linolenic acid t (and other acids) to form pharmaceutical compositions for the 0 treatment of such diseases and disorders, the disclosures are essentially confined to compositions which are administered orally and the investigations 'of Horrobin do not appear to Shave extended to the use of zinc salts of polyunsaturated fatty acids, or cyclic derivatives thereof, for the treatmant 2 5 of certain inflammatory disorders such as rheumatoid arthritis wherein the preparations are applied topically.

The present inventor is also aware of PCT/AU86/00251 (Glyzinc Pharmaceuticals Limited) which discloses the use of a zinc glycerolate complex (Glyzinc) as a slow release formulation of zinc, applied by dermal application to the skin, for treating inflammatory disorders, in particular arthritis.

The present inventor has unexpectedly discovered that certain zinc salts of polyunsaturated fatty acids, or cyclic derivatives thereof, when applied topically possess antiinflammatory activity. The polyunsaturated fatty acids contemplated are the naturally occurring linear alkanoic acids with thre or more ethenoid linkages (available in the diet).

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I Broadly according to this invention therefore, there is provided a treatment of inflammatory disorders, especially rheumatoid arthritis, by the topical or dermal application of an effective amount of a preparation containing one or more zinc salts of polyunsaturated fatty acids, or cyclic derivatives thereof, in association with a pharmaceutically acceptable vehicle or carrier.

The anti-inflammatory activity of the zinc salts of polyunsaturated fatty acids (ZnPUFA) and cyclic derivatives thereof has been successfully tested by the present inventor in rats. Without wishing to be limited to the theory, the inventor believes that the efficacy of the aforesaid zinc salts of PUFA or cyclic derivatives thereof as antiinflammatory agents is attributable to a physical synergy t ,0t° whereby the zinc delivers the PUFA or cyclic derivative thereof via the skin and likewise the PUFA or cyclic derivative thereof delivers the zinc. It is also believed 0*00 I that such physical synergy is accompanied by a biological synergy inasmuch as both zinc alone as zinc at Vi S monoglycerolate) or other PUFA derivatives, or prostenoic t acid and their derivatives, each in themselves, may exhibit some anti-inflammatory activity. However, the antiinflammatory activity of PUFA by itself is destroyed by the S simultaneous administration of aspirin. This is obviously rCC disadvantageous, as aspirin is such a commonly-used drug in the treatment of inflammatory disorders. Surprisingly it has S been found that the Zn salts of PUFA retain their activity in the presence of aspirin.

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Therefore, in a further aspect of this invention, a method of treatment comprises the conjoint

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C ct administration of an effective amount of aspirin and a topical composition comprising an effective amount of one or more of the zinc salts pf the invention.

The zinc salts of PUFA or cyclic derivatives thereof are prepared by neutralising purified free fatty acids with zinc oxide or alternatively with zinc carbonate or zinc hydroxide.

The more saturated zinc salts of PUFA are generally crystalline solids whereas the less saturated ZnPUFA are i;.

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f: t Ii i- 1 '4 generally greasy pastes. The materials should be stored at in a CO or N2 atmosphere for optimum stability.

Preferably, the Ey e L-ee.ake\ fatty acids are selected from eicosapentaenoic (EPA), K-linolenic, o-linolenic, docosahexaenoic (DHA), crepenynic, linoleic and eleostearic acids.

Suitable vehicles/carriers include ethanol, dimethylsulphoxide (DMSO), isopropanol, glycerol, propylene glycol, dimethylacetamide or mixtures thereof. Of course any other solvent compatible with human skin would also be a suitable vehicle/carrier.

In one preferred formulation, the %ZUFA, ZnPUFA or cyclic derivative thereof is in a dry solidified form and dissolved or dispersed in dimethylsulphoxide and subsequently partly diluted with glycerol to reduce skin dessication (in the proportions four parts DMSO to one part glycerol).

In another formulation, the tTZFWE ZnPUFA or cyclic derivative thereof is dispersed in alcohol and subsequently diluted with 0.5 volumes of propylene glycol.

These formulations may be used in the form of a cream or lotion for application to the human skin.

DETAILED DESCRIPTION t t I I c20 C t I C c,c C C C I 1C The following exemplifies one procedure for preparing the c zinc salts of long chain poly-unsaturated fatty acids.

The highly purified (HPLC, purity 96%) methyl esters S were de-esterified by dissolving in 90% aqueous ethanol containing IM potassium hydroxide and allowing to stand at room temperature for 12-16 hours. After acidification to pH3, the Coc free fatty acids were extracted into n-hexane and recovered by S evaporation of the solvent. The completeness of the hydrolysis was confirmed by thin layer chromatography. The fatty acid was dissolved in a 3-fold volume of 85% methanol/water and reacted, with gentle stirring, with a one-half molar equivalent of pure zinc oxide over one hour. The zinc salt, which separated as an oil, was collected, rinsed with cold acetone and dried under a stream of oxygen-free nitrogen.

Synthesis of the zinc salts were confirmed by analysis of the product for zinc content by atomic absorption and NMR spectrophotometry. Solutions of the salts (2 mg/ml in ethanol) (V F

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were diluted 1/100 with water to give solutions of the order of 30 umol/L, depending on the calculated molecular weights of the product being analysed. The atomic absorption was performed in a routine analysis for zinc in biological specimens. A typical analysis for Zn(DHA) 2 yielded the following results: Calculated Molecular Weight Zn(DHA) 2 719 Calculated zinc conc. in analysis solution 27.8 umol/L (2 mg/100 ml) Analysis 23 umol/L.

The ZnPUFA formulations were tested for anti-inflammatory activity using rats and the details of the tests which have been carried out by the inventor are given herebelow.

PHARMACOLOGICAL ASSAY FOR SYSTEMIC (VIS A VIS LOCAL) ANTI-INFLAMMATORY ACTIVITY OF ZnPUFA OR CYCLIC DERIVATIVES THEREOF.

Hooded rats and Dark Agouti (DA) rats were injected with 500 ug of an arthritogenic adjuvant, containing heat-killed Mycobacterium tuberculosis dispersed in 50 ul squalane into their tail base on day 0.

On day 10 (DA rats) or 12 (Hooded rats), the upper back of 2 each of the rats is shaved below the neck (approximately 6cm).

l The zinc salt of a ZnPUFA or cyclic derivative thereof, at a concentration 14 mg/ml in a DMSO-glycerol (4:1 v/v) or ethanolpropylene glycol (2:1 v/v) formulation, was applied once daily for four days to the shaved backs of the rats. On the fifth day the increase in signs of artAiST t s from days 10 (DA rats) or 12 (Hooded rats) are assessed a, compared with those in rats receiving DMSO-glycerol or Ghanol-propylene glycol (i.e.

liquid vehicle only in a dosage of 2.5 ml/kg).

Signs of arthritis are weight loss, increase in rear paw thickness and maximal tail width (measured with a micrometer screw gauge), increase in forepaw inflammation (measured on a scale and general loss of ,condition evidenced by pilorection, loss of hair sheen and ability to climb up a wire frame. These signs of arthritis are measured again three days NT C later (day 17 for DA rats, day 19 for Hooded rats) to assess the rebound in arthritic symptoms of the treated rats on withdrawing treatment.

By this assay, the preparations of zinc PUFA or cyclic derivatives thereof (the PUFA having two or more ethenoid linkages) were shown to have effective anti-inflammatory/ arthritis-suppressant activity when applied to rats with preestablished arthritic disease.

i Effective doses of the reference or ZnPUFA preparations 10 were of the order: -400 umols/kg for zinc monoglycerolate (ZMG) used as a reference lipophilic/hydrophobic zinc complex; -140 umols/kg for zinc o< or -linolenates (18.3); S: -20 umols/kg for zinc EPA or DHA (these being the principal PUFA of marine/fish coils).

Unlike conventional non-steroid anti-inflammatory drugs o l o o(NSAID), which are usually given orally, the present r ,formulations of ZnPUFA or cyclic derivatives thereof did not cause any gastric bleeding. Some NSAID preparations which are also effective applied dermally in DMSO-glycerol vehicles, e.g.

piroxicam or phenylbutazone, still cause gastric irritation S(manifest by gastric haemorrhage in chill-stressed polyarthritic rats).

In addition, applied at three to ten times the dosages used to treat arthritic rats, the preparations of ZnPUFA or cyclic derivatives thereof did not affect weight gain of normal young male rats indicating their lack of systemic toxicity.

Less crystalline Zn salts of branched (iso) or cyclic 1, prostanoic) fatty acids, prepared and applied as described herein, were also anti-inflammatory.

Tests carried out using zinc salts of the fatty acids stearic, undecylenic, propionic and acetic were much less potent and exhibited less anti-inflammatory activity. Likewise other derivatives of UFA, PUFA, prostanoic acid etc., e.g.

methyl esters and triglycerides, were less potent than the 6 NTS mNT corresponding ZnPUFA or Zn prostanoate preparations.

The test data obtained to date has also indicated that the ZnPUFA's and cyclic derivatives thereof are approximately eight times, some as much as 50 times, as potent as ZMG as antiinflammatory agents when applied topically once again indicating that zinc may be acting synergistically with the PUFA or cyclic derivative thereof.

The data from the established rat arthritis assay clearly demonstrate the pharmaco-activity of Zn salts of PUFA and cyclic derivatives thereof as transdermally active, as effective anti-inflammatory agents, and as effective means of delivering zinc, etc. for nutritional supplementation.

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Claims (7)

1. A topical anti-inflammatory or anti-irritant composition comprising an effective amount of a zinc salt of one or more compounds selected from polyunsaturated fatty acids and cyclic derivatives thereof, in a pharmaceutically acceptable vehicle.

2. A topical anti-inflammatory or anti-irritant composition comprising an effective amount of a zinc salt of one or more compounds selected from polyunsaturated fatty acids and cyclic derivatives thereof and aspirin, in a pharmaceutically acceptable vehicle.

3. A composition according to claim 1 or 2, wherein the polyunsaturated fatty acid is eicosapentaenoic acid, g-linolenic acid, C-]inolenic acid, docosahexaenoic acid, crepenynic acid, linoleic acid or eleostearic acid. S4. A composition according to claim 1 or 2, wherein the polyunsaturated fatty acid or cyclic derivative thereof is a branched chain (iso) fatty acid, prostanoic acid, a prostenoic acid or a prostaglandin.

5. A method for treating an inflammatory disorder or dermal irritation which comprises the topical administration to a patient suffering therefrom of an effective amount of a zinc salt of one or more compounds selected from polyunsaturated fatty acids and cyclic derivatives thereof.

6. A method for treating an inflammatory disorder or dermal irritation which comprises the conjoint administration to a patient suffering therefrom of an effective amount of aspirin and a topical composition comprising an effective amount of a zinc salt of one or more compounds selected from V polyunsaturated fatty acids and cyclic derivatives .thereof. 1I -8 vi -II

7. A method according to claim 5 or 6, wherein the polyunsaturated fatty acid is eicosapentaenoic acid,

9-linolenic acid, 0<-linolenic acid, docosahexaenoic acid, crepenynic acid, linoleic acid or eleostearic acid. 8. A method according to claim 5 or 6, wherein the polyunsaturated fatty acid or cyclic derivative thereof is a branched chain (iso) fatty acid, prostanoic acid, a prostenoic acid or a prostaglandin. 9. A composition according to claim 1 or 2, substantially as herein described. 1 10. A method according to claim 5 or 6, substantially as herein described. C t Tr o DATED this 21st day of January 1991. Sr c"t MEDVET SCIENCE PTY LTD S By its Patent Attorneys R K MADDERN ASSOCIATES 4p: C C jc I'( r c '1 c 4 i I