Carbenicillin: A New Semisynthetic Penicillin Active against Pseudomonas pyocyanea

Abstract

Carbenicillin is a new semisynthetic penicillin active against Pseudomonas pyocyanea. The compound shows a broad spectrum of activity against Gram-positive and Gram-negative bacteria and is active against strains of Proteus vndgaris, Pr. rettgeri, and Pr. morganii, which are typically resistant to ampicillin. With a very heavy inoculum of Ps. pyocyanea marked inhibition of growth occurs with carbenicillin at 25 to 50 Ag./ml., but some very scanty growth may persist even at concentrations of 125 to 250 ug./ml. With a slightly smaller inoculum complete inhibition of growth occurs at 25 to 50 ttg./ml. Carbenicillin is bactericidal and is not highly bound to serum protein. Carbenicillin is not absorbed when given by mouth, but high concentrations of the drug are obtained in serum after intramuscular or intravenous administration, and these levels are increased and are more prolonged with concomitant use of probenecid. Carbenicillin is excreted in high concentration in the urine. © 1967, British Medical Journal Publishing Group. All rights reserved.