GR 20263, a new broad-spectrum cephalosporin with anti-pseudomonal activity

Abstract

GR 20263 is a new broad-spectrum injectable cephalosporin which is stable to most β-lactamases. Its in vitro activities were of the same order as those of cefotaxine against most gram-negative bacteria, were clearly inferior to cefotaxime against Staphylococcus aureus, but were significantly more active against Pseudomonas aeruginosa. Against the 25 strains used, GR 20263 was significantly more active than any of the other agents tested: piperacillin, azlocillin, gentamicin, amikacin, and carbenicillin. GR 20263 protected mice against experimental infections with P. aeruginosa more effectively than other β-lactam antibiotics; its general effectiveness in this test was comparable with gentamicin. Studies on human volunteers showed that it produced high, long-lasting blood levels, with much of the antibiotic being recovered in the urine. Intramuscular and intravenous injections were well tolerated by the volunteers, and there were no untoward side effects.