This invention relates to novel pharmaceutical formulations, in particular to aqueous suspension formulations containing tipredane.

US Patent No 4,361,559 discloses a large number of 3-ketoandrostenes which are described as having useful anti-inflammatory activity, including useful activity in the topical treatment of allergy and asthma. This patent also specifically discloses (11)3,17α)-17-(ethylthio)-9α- fluoro-ll/9-hydroxy-17-(methylthio)-androsta-1,4-diene-3-one , which is known by the INN generic name tipredane.

We have now found that tipredane has useful anti-inflammatory activity when administered to the nose.

The most favoured vehicle for administering a drug to the nose is water as this is likely to give maximum bioavailability. However, tipredane has a water solubility below 0.002 mg/ml at room temperature. Although it may be possible to increase water solubility by the use of co-solvents or solubilising agents, such co-solvents and agents frequently cause nasal stinging and/or interact with the active ingredient. Attempts at increasing the aqueous solubility of tipredane using /8-cyclodextrin derivatives were also unsuccessful. Tipredane has a relatively poor oil solubility, which prevents the preparation of satisfactory emulsion formulations.

In general, powder formulations of non water soluble drugs for application to the nose are not favoured, in that the drug is being presented to the nose in a form that is unlikely to be readily bioavailable.

Propellant driven powder formulations are not favoured for tipredane, in that CFC driven formulations are unsatisfactory environmentally and HFC propellants are difficult to formulate.

Surprisingly, we have now found that it is possible to formulate tipredane as an aqueous suspension and control nasal inflammatory conditions.

According to the invention there is provided an aqueous suspension formulation containing, as active ingredient, tipredane.

The formulation according to the invention is advantageous in that it is more efficacious, has a longer effect, produces fewer or less severe side-effects, or has other advantageous properties when compared with comparable formulations of other compounds or with other, known formulations of the active ingredient. In addition, the stability of the active ingredient may be enhanced in the ₅ formulation of the invention, which is surprising in view of the known tendency of the active ingredient to oxidise.

The active ingredient is preferably present in the formulation at a concentration of from 0.005% to 1.5% w/w, more preferably from 0.01 to 0.1% and especially from 0.2% ₀ to 0.4% w/w.

The formulation will generally contain a surfactant. Although ionic surfactants such as sodium lauryl sulphate may be used, we prefer the surfactant to be a non-ionic surfactant. Non-ionic surfactants that may be mentioned sinclude glycol and glycerol esters, acetoglycerides, macrogol esters, macrogol ethers and sorbiton esters. We have found that the block copolymers of poloxyethylene- polyoxypropylene, known as poloxamers with the general formula HO(C ₂ H ₄ 0) _a (C ₃ H ₆ 0) _b (C ₂ H ₄ 0) _a H, in dwhich a is 2 to 130 and b is 15 to 67 give particularly stable formulations.

We prefer poloxamers with an average molecular weight of between 4000 and 20,000, more particularly between 6000 and 15,000. A particularly preferred poloxamer that may be snentioned is that known as poloxamer 188 (poloxalkol) in

which a in the general formula averages 75 and b averages 30. This has a molecular weight of about 8350.

The concentration of the surfactant in the formulation will depend inter alia on the particular surfactant used, but will in general be from 0.05% to 10% w/w, more preferably from 0.05% to 5% w/w, especially from 0.05% to 0.5% w/w. We have found that the use of such low concentrations of surfactant, eg about 0.1 %w/w, leads to particularly stable formulations which show improved resistance to oxidation.

The formulation may, if desired, contain an effective proportion of a pharmaceutically acceptable preservative or sterilising agent. Suitable preservatives include pharmaceutically acceptable quarternary ammonium compounds. The preferred preservatives amongst the quarternary ammonium compounds are the alkyl benzyl dimethyl ammonium chlorides and mixtures thereof, eg that known generically as ^* benzalkonium chloride' . The preservative may be used at a concentration of from about 0.005% to 0.10%, preferably 0.005% to 0.05%, eg about 0.01% w/w.

The formulation will generally also contain a pseudoplastic thixotropic viscosity modifying agent. Suitable thixotropic viscosity modifying agents which may be used include carboxy vinyl polymers, alginates, cellulose and its derivatives, for example hydroxypropyl methylcellulose and dispersible cellulose, which is a co-blend of microcrystalline cellulose and sodium carboxymethyl cellulose sold commercially as Avicel RC-591. If present, the thixotropic viscosity modifying agent will be at a concentration at which the resulting viscosity of the formulation is suitable for its intended use. The viscosity of the formulation may be varied between quite wide limits (typically between 0.5 and 5.0% w/w) but, in

general, will be relatively low at high shear rates (to enable dispensing, eg as a spray from a conventional nasal pump) and relatively high at low shear rates.

We prefer the formulation according to the invention to be isotonic with the nasal mucosa. The formulation may therefore contain a tonicity adjusting agent, eg glycerol, at a concentration of from about 0.1% to 2.0%, more preferably 0.5% to 1.0% w/w. ₀ The formulation may additionally contain conventional excipients eg electrolytes. A particularly preferred electrolyte is sodium chloride. Sodium chloride is useful as a flocculating agent and may also alter the tonicity of the formulation. ₅ In general, the overall proportion and concentration of excipients may be varied within fairly wide ranges, provided that the resulting solution is stable and non-irritant when applied to the nasal tissues.

As a particularly preferred aspect of the invention, othere is provided an aqueous formulation comprising a) from 0.1 to 1.25% w/w of tipredane as active ingredient, b) from 0.05% to 10% w/w of a non-ionic surfactant, c) from 0.5 to 5% w/w of a thixotropic viscosity ₅ modifying agent, and d) from 0.1 to 2.0% w/w of a tonicity adjusting agent. The formulation of the invention may be made up, for example, by dispersing the active ingredient, using the surfactant as wetting agent, and dispersing or dissolving othe thixotropic viscosity modifying agent (if included) and other excipients (if included) in freshly distilled water, adding to this solution an aqueous solution of the preservative (if included) , making the solution up to the desired volume with distilled water, and stirring. The 5formulation is preferably made up under aseptic conditions.

According to another aspect of the invention there is provided a method of treatment of conditions of the nose, in which conditions allergic or immune reactions play a contributory part, which method comprises administration of a formulation according to the invention to a patient suffering from, or susceptible to, such a condition.

The dosage administered will of course vary with the condition to be treated and with its severity. However, in general, a dosage of about 400μg is indicated. The dose may be administered up to four times to each nostril at any one dosing session and from 1 to 4 times a days. We prefer to administer the formulation once or twice daily.

Conditions of the nose in which may be treated the ethod of the invention include seasonal rhinitis, eg hay fever; perenial rhinitis; nasal polyps and allergic manifestations of the nasopharynx.

The invention is illustrated, but in no way limited, by the following Example. Example Ingredients

Active ingredient 0.308 w/w

(equivalent to 400μg per actuation)

Poloxamer 188 0.100 Sodium chloride Ph.Ew/USP 0.584

Glycerol 1.000

Benzalkonium chloride ¹ 0.010

Avicel RC-591 2.000

Purified water Ph.Ew/BP/USP to 100.00

¹ added as a 50% w/v solution

The formulation has been found to be chemically and physically stable when using an identical vehicle containing tipredane at the following strengths: 0.0096% w/w (equivalent to 12.5μg per actuation)

0.0192% W/W (equivalent to 25μg per actuation) 0.0385% W/W (equivalent to 50μg per actuation) 0.0770% W/W (equivalent to lOOμg per actuation) 0.1540% W/W (equivalent to 200μg per actuation) 0.692% W/W (equivalent to 800μg per actuation) 1.231% W/W (equivalent to 1600μg per actuation)

Manufacturing process

Tipredane is dispersed in an aqueous solution of poloxamer 188, glycerol, sodium chloride and benzalkonium chloride. This is added to a dispersion of microcrystalline cellulose co-blend in water and mixed until homogeneous. The suspension is made to weight with more water before filling into bottles. ₅ The tipredane is preferably micronised material, with a mean particle size of 5μg and not more than 20% by weight of the tipredane having a particle size of > lOμm.

If necessary, the pH of the aqueous suspension can be _Q adjusted by addition of acid or base as appropriate, to give a pH of between 4.5 and 7.5.

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