GB2148894A - Aluminium salts of oxazole derivatives - Google Patents

Abstract

New aluminium hydroxide salts of oxaprozin which have formula I <IMAGE> where x is </= 2. are described, together with pharmaceutical formulations containing them. The new salts are anti-inflammatory agents. They are prepared by reacting a water-soluble stable aluminium salt with a water-soluble salt of oxaprozin in an aqueous medium.

Description

SPECIFICATION Oxazole derivatives This invention relates to oxazole derivatives and in particularto novel salts and pharmaceutical compositions containing them.

Oxaprozin, namely ss-(4,5-diphenyloxazol-2-yl) propionic acid has shown interesting anti-inflammatory activity and is currently undergoing clinical trials in humans as an anti-inflammatory agent.

Unfortunately oxaprozin has a very bitter taste. This can be masked in use by making the dosage forms as capsules or film coated tablets. However, where large single doses of oxaprozin are required this solution to the problem is not satisfactory. Research has been carried out to devise pharmaceutical preparations which allow for once a day dosing. Such preparations include chewable tablets containing a relatively large amount of oxaprozin and suspensions. The bitter taste of oxaprozin has proved to be a disadvantage of such preparations.

In our previous researches we have prepared various salts and have found that the calcium salt does not possess the bitterness of the parent acid (see UK Patent Specification 2097389A). We have now prepared novel aluminium derivatives of oxaprozin and found that they also disguise the taste of oxaprozin.

The present invention therefore provides aluminium hydroxide salts of p-(4,5-diphenyloxazol-2-yl) propionic acid and pharmaceutical formulations containing them.

The novel compounds preferably have the general formula I

wherein x 62. x need not be a whole integer.

A preferred compound of the invention has the formula

The compounds of the invention may be prepared in the form of hydrates.

The invention includes a method of preparing compounds of formula I which method comprises treating a water-soluble salt of oxaprozin with a water-soluble stable aluminium salt. The stable aluminium salt is preferably aluminium sulphate but may be aluminium nitrate.

The water-soluble salt of oxaprozin may be an alkali-metal salt e.g. the sodium or potassium salt, an ammonium salt or an amine salt.

Preferably the reaction is carried out in an aqueous medium.

The invention also comprises a method for preparing a palatable oral pharmaceutical preparation characterised in that a compound of formula I is mixed with a pharmaceutical carrier and formulated into preparations for oral administration.

The pharmaceutical formulations include solids and liquids. Any suitable carrier known in the art can be used to prepared the pharmaceutical composition. In such a composition, the carrier is generally a solid or liquid, or a mixture of a solid and a liquid.

Solid form compositions include powders, granules, tablets, capsules (e.g. hard and soft gelatin capsules), suppositories and pessaries. A solid carrier can be, for example, one or more substances which may also act as flavouring agents, lubricants, solubilisers, suspending agents, fillers, glidants, compression aids, binders, effervescent excipients ortablet-disintegrating agents; it can also be an encapsulating material. In powders the carrier is a finely divided solid which is in admixture with the finely divided active ingredient. In tablets the active ingredient is mixed with a carrier having the necessary compression properties in suitable proportions and compacted in the shape and size desired. The powders and tablets preferably contain up to 99%, e.g. from 10 to 80%, preferably 25 to 75% of the active ingredient.Suitable solid carriers include, for example, calcium phosphate, magnesium stearate, talc, sugars, lactose, dextrin, starch, gelatin, cellulose, methyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidone, low melting waxes and ion exchange resins.

The term "composition" is intended to include the formulation of an active ingredient with encapsulating material as carrierto give a capsule in which the active ingredient (with or without other carriers) is surrounded by the carrier, which is thus in association with it. Similarly cachets are included.

Liquid form compositions include, for example, suspensions, emulsions, syrups and elixirs. The active ingredient, for example, can be suspended in a pharmaceutically acceptable liquid carrier such as water, an organic solvent, a mixture of both or pharmaceutically acceptable oils or fats. The liquid carrier can contain other suitable pharmaceutical additives such as solubilisers, emulsifiers, buffers, preservatives, sweeteners, flavouring agents, suspending agents, thickening agents, colours, viscosity regulators, stabilisers or osmoregulators.Suitable examples of liquid carriers for oral administration include water (particularly containing additives as above e.g. cellulose derivatives, preferably sodium carboxymethyl cellulose solution), alcohols (including monohydric alcohols and polyhydric alcohols e.g. glycerol and glycols) and their derivatives, and oils (e.g. fractionated coconut oil and arachis oil).

Preferably the pharmaceutical composition is in unit dosage form, e.g. as tablets or capsules. In such form, the composition is sub-divided in unit dose containing appropriate quantities of the active ingredient; the unit dosage forms can be packaged compositions, for example packeted powders. The unit dosage form can be, for example, a capsule or tablet itself, or it can be the appropriate number of any such compositions in package form. The quantity of the active ingredient in a unit dose of composition may be varied or adjusted from 100 mg or less to 800 mg or more, according to the particular need. Preferably the compound of formula I is present in an amount from 200 to 700 mg, preferably from 350 to 700 mg.

The invention also provides a chewable tablet comprising a compound of formula I, a chewable base, a binding agent and a lubricant. The tablet may include finely divided silica, sweetening agents and flavouring agents. The chewable base is preferably mannitol. Other chewable bases which may be used are sorbitol, directly compressible sucrose, Sugartab - a directly compressible blend of sucrose and invert sugar, or Sweetrex - a directly compressible special blend of sugars which is said to be sweeter than sucrose.

A chewable tablet according to the invention comprises: Compound of formula 1 550-750 mg Chewable base 300-600 mg a binding agent, a sweetening agent and a lubricant.

A preferred chewable tablet comprises: Compoundofformula 1 550-750 mg Mannitol or sucrose 300-600 mg binding agent up to 300 mg lubricant sweetening agent flavouring agent The binding agent preferably comprises one or more of the following polyvinyl pyrrolidone, starch, or cellulose binding agents eg. methylcellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose and microcrystalline cellulose.

One particular chewable tablet according to the invention may comprise: Compound of formula 1 550-750 mg Mannitol or sucrose 300-600 mg Polyvinyl pyrrolidone 30-70 mg Starch 100-300 mg finely divided silica up to 40 mg magnesium stearate up to 50 mg sweetening agent and flavouring agent.

In the above formulation the polyvinyl pyrrolidone may be replaced by methyl cellulose.

A suspension according to the invention comprises compound of formula 1, wetting agents, preserving agents, suspending agents, sweeteners and water. Flavouring agents may be added. The amount of compound of formula I may be in the range from 0.70-1.99 per 5ml of suspension.

The preferred wetting agent is glycerol as it also imparts sweetness and viscosity to the suspension. When glycerol is used it may not be necessary to use an additional sweetening agent.

A preferred suspension comprises compound offormula 10.70-1.909 per semi, and glycerol.

The dosage forms of the present invention may be made into effervescent tablets comprising aluminium oxaprozin, an effervescing agent, binding agent, and a lubricant. The effervescing agent may comprise sodium glycine carbonate andlor sodium bicarbonate.

Another specific dosage form according to the invention is an effervescent tablet comprising: Compound of formula 1 550-750 mg Mannitol or sucrose 300-600 mg Sodium glycine carbonate 100-200 mg Sodium bicarbonate 100-200 mg Citric acid 300-400 mg Binding agent 50-150 mg finely divided silica up to 40 mg lubricant eg dl leucine up to 100 mg or magnesium stearate sweeteners and flavouring agents.

The invention is illustrated by the following examples Example 1 Aluminium hydroxide di(4, 5-diph en yl-2-oxazolepropiona te) dihydrate 4,5-Diphenyl-2-oxazolepropionic acid (29.39, 0.1 mole) was suspended in 200 ml of water and 10N sodium hydroxide solution (10 ml) was added to give a clear solution, to which was added a solution of aluminium sulphate hexadecahydrate (21.03 g, 0.003 mole) in water (150 ml), giving a thick precipitate. This was collected, washed with water, re-slurried and collected, but the solid (30.6 g) was found to contain some free oxaprozin.Fifteen grams of this material was washed with acetone and collected to give aluminium hydroxide di(4,5-diphenyl-2-oxazolepropionate) (formula II), dihydrate (10.6 g, equivalent to 21.6 g, 65%) m.p. 225-227"C Found: C,65.1; H, 4.79; N, 3.95%. Al 4.48 C36H29AIN207.2H2O requires C, 65.1; H, 5.00; N, 4.21%. Al 4.06.

Example 2 Preparation of aluminium hydroxide di(4, 5-diphenyl-2-oxazole propionate)dihydrate

4,5-Diphenyl-2-oxazole propionic acid (29.3 g, 0.1 mole) was suspended in 400 ml of water and iON sodium hydroxide solution (10.3 ml) was added to give a clear solution to which was added concurrently a solution of aluminium sulphate hexadecahydrate (15.75 g, 0.025 mole) in water (150 ml) and a solution of sodium bicarbonate (4.2 g, 0.05 mole) in water (150 ml). The resulting suspension was collected, washed with water and dried to give aluminium hydroxide di(4,5-diphenyl-2-oxazole propionate) dihydrate (31.8 g,96%).

Example 3 Preparation of aluminium dihydroxide (4,5-diphenyl-2-oxazole propionate).

4,5-Diphenyl-2-oxazolepropionic acid (29.3 g, 0.1 mole) was suspended in water (400 ml) and 10N sodium hydroxide solution (10.3 ml) was added to give a clear solution to which was added concurrently a solution of aluminium nitrate nonahydrate (37.5 g, 0.1 mole) in water (200 ml) and a solution of sodium bicarbonate (16.8 g, 0.2 mole) in water (200 ml). The resulting suspension was collected, washed with water and dried to give aluminium dihyroxide (4,5-diphenyl-2-oxazole propionate) (359).

Example 4 Chewable tablet The aluminium salt of Example 1 is formulated into chewable tablets of the following composition per tablet mg per tablet Aluminium oxaprozin(formula 11) 680* Mannitol 500 Polyvinyl pyrrolidone 46.6 Water q.s.

Starch 1500 212.0 Saccharin sodium 1.5 Liquorice 2.20 Aniseed 2.20 Aerosil 200 (finely divided 8.00 silica) Magnesium stearate 38.0 1490.5 * Equivalent to 600 mg oxaprozin The tables are prepared by the following procedure. The polyvinyl pyrrolidone is dissolved in sufficient water and the compound II granulated with it. Mannitol previously passed through a 30 mesh screen is added. The wet granules are dried and graded to 12 mesh screen at 50"C. The dried granules are passed through 16 mesh screen. The liquorice and aniseed are dispersed on to some Starch 1500. The rest of the ingredients are weighed out and blended with the dried granules and the flavoured Starch 1500.

The tablets are compressed on a standard tabletting machine to form chewable tablets. The tablets are quite palatable in contrast to similar tablets of oxaprozin which were so bitter as to be unpalatable.

Example 5 A suspension of the aluminium salt (from Example 1) is prepared to have the following composition.

% wlv Aluminium oxaprozin (formula 11) 13.60 *Glycerin 40.00 Avicel CL611 (microcrystalline 1.20 cellulose) Grapefruit or other flavour 0.10 Sodium methyl parahydroxybenzoate 0.04 Sodium ethyl parahydroxybenzoate 0.06 Sodium propyl parahydroxybenzoate 0.10 Purified water to 100 ml * Level may vary from 1 0-50%w/v, water being adjusted accordingly.

The parahydroxybenzoates are preservatives, the amounts may be varied. A suitable colour may be added. Glycerin functions as wetting agent and sweetener.

Method of Manufacture The Avicel is dispersed in approximately 90% of the water. The glycerin is added and mixed thoroughly.

The aluminium oxaprozin is added to the glycerin/Avicel mixture and dispersed. The preservatives are then added to the suspension as a 40% concentrate in water. The flavour is added and the suspension adjusted to volume with water.

Example 6 Effervescent tablet An effervescent tablet is made up according to the following formulation: mgitablet Aluminium oxaprozin of formula 11 680.00 Polyvinyl pyrrolidone (PVP) 100.00 Sodium glycine carbonate 150.00 Sodium bicarbonate 150.00 Mannitol 429.50 *IMS OP 74 qs Citric acid an hydros 350.00 Sodium saccharin 4.00 Lemon 842601/B 4.00 dl Leucine 100.00 1967.50 Process ofpreparation Weigh out and sieve through a No. 30 screen the aluminium salt 11, sodium glycerin carbonate, sodium bicarbonate and mannitol. Granulate with an IMS solution of PVP. Pass the wet mass through a No. 12 screen, and after drying through a No. 16 screen. Blend the dried granule with citric acid anhydrous, sodium saccharin, flavour and leucine in a humidity controlled area. Compress into tablets using 19mm tooling and assemble into a pack which excludes moisture.

* Industrial Methylated Spirits (99.5% Ethyl Alcohol) Example 7 Chewable tablet Chewable tablets are made up according to the following formulation: mg per tablet Aluminium oxaprozin of formula 11 680.0* Mannitol 500.0 **Methocel A15 45.0 Water qs Starch 1500 212.1 Saccharin sodium 1.5 Liquorice 2.2 Aniseed 2.2 Aerosil 200 22.5 (finely divided silica) Magnesium Stearate 15.0 1480.5 * Equivalent to 600 mg Oxaprozin ** Methyl Cellulose Process ofpreparation Dissolve Methocel A15 in deionized water and leave overnight at 4"C. Mix the aluminium salt Il in a planetary mixer with mannitol and granulate with Methocel aqueous solution. Blend the remaining excipients in a suitable planetary mixer.Compress a suitable compression machine fitted with 19 mm punches.

Example 8 Chewable tablets are made up according to the following formulation using the procedure described in Example 7 mg per tablet Aluminium oxaprozin of formula ll 680.0 Mannitol 500.0 Methocel A15 premium 45.0 Water q.s.

Microcrystalline cellulose 212.1 Saccharin 1.5 Liquorice 2.2 Aniseed 2.2 Aerosil 200 22.5 Magnesium stearate 15.0 1480.5 Example 9 Effervescent tablet A) Wet Granulation mg per tablet Aluminium oxaprozin of formula Il 680.0* **Dipac 200.0 Sodium glycine carbonate 150.0 Hydroxy propyl cellulose 100.0 IMS (Industrial Methylated Spirit) q.s.

B) Powder Blending Mixture Dipac 199.1 Sodium bicarbonate coated 150.0 Citric acid coated 350.0 Liquorice 2.2 Aniseed 2.2 Aerosil 200 10.0 Sodium saccharin 4.0 Magnesium stearate 20.0 1867.5 * Eqivalent to 600 mg oxaprozin ** Directly compressible sucrose.

The aluminium oxaprozin, Dipac and sodium glycine carbonate are mixed in a planetary blender. The hydroxypropylcellulose is dissolved in IMS and mixed with the granulated powder blend. The mass is passed through 12 mesh screen and dried. The dried granules are passed through a 16 mesh screen and mixed with the remaining excipients in a planetary blender. The mixture is then compressed on a suitable compression machine fitted with 9mm FBE punches.

All mesh sizes in the above examples are British standard sizes.

12 mesh = 1400 microns; 16 mesh = 1000 microns 30 mesh = 500 microns.

Claims (24)

1. A compound of formula I

where xis < 2.

2. A compound of formula II

3. A compound of formula Ill

4. A pharmaceutical formulation comprising a compound of formula I, as defined in claim 1, as defined in claim 1, and a pharmaceutically acceptable carrier.

5. A pharmaceutical formulation as claimed in claim 4, in unit dosage form, wherein the amount of compound of formula I is in the range from 100 mg to 800 mg per unit dose.

6. A pharmaceutical formulation as claimed in claim 5, in the form of a chewable tablet, comprising a compound of formula I, a chewable base, a binding agent and a lubricant.

7. A pharmaceutical formulation as claimed in claim 6, wherein the chewable base is mannitol, directly compressible sucrose or sorbitol.

8. A pharmaceutical formulation as claimed in claim 5, in the form of an effervescent tablet comprising a compound of formula I, an effervescing agent, a binding agent and a lubricant.

9. A pharmaceutical formulation as claimed in any one of claims 5-8, including a binding agent selected from polyvinyl pyrrolidone, starch, methylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose and microcrystalline cellulose.

10. Achewable tablet comprising: compound of formula I, as defined in claim 1 550-750 mg; chewable base 300-600 mg; a binding agent, a sweetening agent and a lubricant.

11. Achewable tablet comprising: compound of formula I, as defined in claim 1 550-750 mg; mannitol or sucrose 300-600 mg; binding agent up to 300 mg; lubricant, sweetening agent and/or flavouring agent.

12. A chewable tablet comprising: compound of formula I, as defined in claim 1 550-750 mg; mannitol or sucrose 300-600 mg; polyvinylpyrrolidone or methylcellulose 30-70 mg; starch 100-300 mg; finely divided silica up to 40 mg; magnesium stearate up to 50 mg; sweetening agent and flavouring agent.

13. A pharmaceutical formulation in the form of a suspension for oral administration comprising: compound offormula I, as defined in claim 1; wetting agent, preserving agent, flavouring agent, suspending agent and water.

14. An effervescent tablet comprising: compound of formula 1550-750 mg mannitol orsucrose300-600 mg sodium glycine carbonate100-200 mg sodium bicarbonate100-200 mg citric acid300-400 mg binding agent 50-150 mg finely divided silicaup to 40 mg lubricantupto 100 mg sweetener and flavouring agent.

15. A pharmaceutical formulation as claimed in any one of claims 4 to 9 or 13wherein the compound of formula I has the formula II as claimed in claim 2.

16. A pharmaceutical formulation as claimed in any one of claims 4 to 9 or 13 wherein the compound of formula I has the formula Ill as claimed in claim 3.

17. Atablet as claimed in any one of claims 10, 11,12 or 14, wherein the compound of formula I has the formula II.

18. A tablet as claimed in any one of claims 10, 11, 12 or 14, wherein the compound of formula I has the formula Ill.

19. A pharmaceutical formulation as claimed in claim 4, substantially as hereinbefore described in any one of Examples 4 to 9.

20. A method of preparing a compound of formula I, as claimed in claim 1, which method comprises treating in an aqueous medium a water-soluble salt of oxaprozin with a water-soluble stable aluminium salt.

21. A method as claimed in claim 20, wherein the aluminium salt is aluminium sulphate or aluminium nitrate.

22. A method as claimed in claim 20, wherein the water-soluble salt of oxaprozin is an alkali-metal, ammonium, or amine salt.

23. A method as claimed in claim 20, substantially as hereinbefore described in any one of Examples 1,2 or3.

24. A compound of formula I as claimed in claim 1, whenever prepared by a method as claimed in any one of claims 20 to 23.