Tilmicosin is a semi-synthetic antibiotic derived from desmycosin (tylosin B), a minor co-metabolite of tylosin. Tilmicosin is produced by reductive amination of desmycosin. Desmycosin itself is prepared by the partial hydrolysis of tylosin with the loss of the mycarosyl sugar. The piperidinyl group at C20 of tilmicosin provides a wider spectrum of antibiotic action, in particular good protection against Pasteurella in livestock.