The present invention relates to a process for the preparation of erythromysin derivatives, in particular telithromycin of formula (I) and its pharmaceutically acceptable salts, providing the isolated intermediates in crystalline form of superior stability and purity.

The present invention relates to stable amorphous 3-De[(2,6-dideoxy-3-C-methyl-3-O-methyl-alpha-L-ribohexopyranosyl)oxy]-11,12-dideoxy-6-O-methyl-3-oxo-12,11-[oxycarbonyl[[4-[4-(3-pyridinyl)-1H-imidazol-1-yl]butyl]imino]]erythromycin (telithromycin), methods for the preparation thereof, the use of stable amorphous telithromycin in the treatment of bacterial infections and to pharmaceutical compositions comprising stable amorphous telithromycin.

The present invention relates to stable amorphous 3-De[(2,6-dideoxy-3-C-methyl-3-O-methyl-a-L- ribohexopyranosy l)oxy]- 1 1 , 12-dideoxy-6-O-methy 1-3-oxo- 12,11 -[oxycarbonyl[[4-[4-(3-pyridinyl)- 1 H- imidazol-l-yl]butyl]imino]]erythromycin (telithromycin), methods for the preparation thereof, the use of stable amorphous telithromycin in the treatment of bacterial infections and to pharmaceutical compositions comprising stable amorphous telithromycin.