Antibacterial and pharmacokinetic properties of M14659, a new injectable semisynthetic cephalosporin

In vitro and in vivo antibacterial activities and pharmacokinetics of M14659 were investigated. In vitro activity of M14659 was superior to that of ceftazidime against Staphylococcus aureus. Against Gram-negative bacteria except Pseudomonas aeruginosa, its activity was almost equal to that of ceftazidime. M14659 was more active against P. aeruginosa including multi-drug resistant strains than cefsulodin, cefoperazone or ceftazidime. Affinities of M14659 for penicillin-binding proteins (PBPs) of Escherichia coli and P. aeruginosa were 2 to 14 times higher for PBP-1A and PBP-1B than found for ceftazidime, and almost the same for PBP-3. In vivo activity of M14659 against S. aureus was superior to that of cefamandole, cefotaxime or ceftazidime. Against Gram-negative bacteria including P. aeruginosa, M14659 was 2 to 220 times more active than cefotaxime or ceftazidime. Plasma half-life of M14659 in mice was about 3 times longer than that of ceftazidime. M14659 administered intravenously to mice was mainly excreted in urine without metabolism, and its recovery rate was almost equal to that of ceftazidime.