DERIVATIVES OF(6R,7R)-7-((Z)-2-(2-AMINOTHIAZOL-4-YL)-2-(CARBOXY-(LOWER ALKYL OR CYCLOALKYL)OXYIMINO)ACETAMIDO)-3-(1-PYRIDINIUM-METHYL)CEPH-3-EM-4-CARBOXYLATE,PROCESS FOR THEIR PREPARATION AND PHARMACEUTICAL COMPOSITIONS COMPRISING THEM

摘要

Cephalosporin antibiotics of the general formula IMAGE (I) (wherein Ra and Rb, which may be the same or different, each represent a C1-4 alkyl group or Ra and Rb together with the carbon atom to which they are attached form a C3-7 cycloalkylidene group; and R4 represents hydrogen or a 3- or 4-carbamoyl group) exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms. A particular antibiotic compound of formula (I) possessing excellent antibacterial activity against strains of Pseudomonas organisms, as well as other valuable therapeutic properties, is (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimono) acetamido]-3-(1-pyridiniummethyl)-ceph-3-em-4 carboxylate. The invention also includes the non-toxic salts and non-toxic metabolically labile esters of compounds of formula (I). Also described are compositions containing the antibiotics of the invention and processes for the preparation of such antibiotics.