A process for the preparation of pure, crystalline, sparingly soluble salts of phenoxymethylpenicillin.

摘要

Substantially pure, crystalline, salts of phenoxymethylpenicillin with a benzimidazole compound are produced by reacting phenoxymethylpenicillanic acid, or a metal salt thereof, with a benzimidazole compound of formula FORM:1023385/C2/1 wherein R1 is an aliphatic hydrocarbon residue containing at least one secondary or tertiary amino group and R2 is an aralkyl or substituted aralkyl residue, or a salt thereof, in a suspending liquid wherein the phenoxymethyl penicillin is difficultly soluble and the benzimidazole is readily soluble at a temperature not substantially exceeding 60 DEG C., adding to the resulting mixture seed crystals of the final product in an amount between 5 and 10% of said desired salt, said seed crystals having a particle size between 5 and 20 microns, and slowly cooling the seeded reaction mixture. An initial temperature of 40 to 50 DEG C., with cooling not in excess of 50 DEG C. every 30 minutes, together with stirring, is preferable. Dispersing agents such as lecithin may be present. The above penicillin V salts of benzimidazole may be administered parenterally in aqueous suspension with or without a dispersing aid.