METHOD OF AZITHROMYCIN DIHYDROCHLORIDE PREPARING Russian patent published in 1999 - IPC

FIELD: organic chemistry, antibiotics. SUBSTANCE: invention relates to a new method of preparing azithromycin dihydrochloride that is a pharmaceutically acceptable salt of an antibiotic azithromycin that is used as an antibacterial agent showing broad spectrum of effect. Invention describes a method of preparing azithromycin dihydrochloride that involves an interaction of azithromycin monohydrate or azithromycin dihydrate dissolved in lower (C₁-C₄)-alcohol or lower (C₃-C₆)-ketone with 1.6-2 equivalents of hydrogen chloride gas dissolved in dry lower (C₁-C₄)-alcohol at concentration 12-20% (mass/volume) and at temperature from 10 C to 15 C. Obtained substance is precipitated with a precipitating agent at temperature from 10 C to 25 C at ratio solvent to precipitating agent from 1:1.8 to 1:8 (vol./vol.) followed by its isolation by filtration. EFFECT: development of the improved method of preparing based on economical and technical points of view. 2 cl, 4 ex