GB834579A - Hydrohalide salts of oxytetracycline - Google Patents

Abstract

An hydrohalide salt of oxytetracycline is obtained by dissolving up to about 0.3 g./ml. amphoteric oxytetracycline in an aliphatic alcohol of up to six carbon atoms in the presence of a solubilizing agent consisting of (a) 0.01 to 0.05 g./ml. of a hydrogen halide, (b) 0.02 to 0.3 g./ml. of a soluble alkali metal halide, (c) 0.02 to 0.3 g./ml. of a soluble alkaline earth metal halide other than calcium chloride, or (d) 0.02 to 0.3 g./ml. of a soluble zinc halide, and subsequently treating said solution with 0.02 to 0.06 g./ml. of a hydrogen halide thereby precipitating said oxytetracycline hydrohalide salt. The metal halide should be soluble in the particular solvent selected to the extent of at least 0.02 g./ml. at ordinary temperatures. Useful combinations are calcium bromide in methanol or ethanol, strontium chloride in methanol, magnesium chloride in methanol, sodium bromide in methanol, zinc chloride in methanol and lithium chloride in methanol. Suitable hydrogen halides are anhydrous hydrogen chloride, concentrated hydrochloric acid and concentrated hydrobromic acid. Amphoteric oxytetracycline may be produced in situ by treating a suspension of crude oxytetracycline hydrohalide with an organic amino in the aliphatic alcohol. The suspension of oxytetracycline so produced is then treated with an alcohol solution of the metal halide, filtered and the hydrohalide salt precipitated by the addition of the appropriate acid. Suitable amines are pyridine, piperidine, triethylamine, trimethylamine and ethanolamine. Specification 684,417 is referred to.