Syn-lsomers of 7-substituted-3-cephem-4-carboxylic acid esters of the formula:
wherein R is lower alkanoyloxy (C2-C6 alkyl, isobutyryloxymethyl, 2-ethylbutyryloxymethyl or 3,3-dimethylbutyryloxymethyl, or salts thereof, and processes for their preparation and pharmaceutical composition containing them.
式中R为低级烷酰氧基(C2-C6烷基、异丁酰氧基甲基、2-乙基丁酰氧基甲基或3,3-二甲基丁酰氧基甲基)的7-取代-3-头孢-4-
羧酸酯的异构体或其盐及其制备方法和含有它们的药物组合物。