Abstract
Cefazolin, 7- [1- (1H) -tetrazolylacetamido] -3- [2- (5-methy1-1, 3, 4-thiadiazolyl) -thiomethyl] -Δ3-cephem -4-carboxylic acid, is a new antibiotic derived from 7-aminocephalosporanic acid. Cefazolin is a broad-spectrum antibiotic active against penicillinase-producing Staphylococcus aureus also. Cefazolin was apparently bactericidal in vitro at or above the minimal inhibitory concentration. In mice, Cefazolin provided an excellent effect against experimental infections caused by various strains of Staph. aureus (penicillin-susceptible and penicillin-resistant), Diplococcus pneumoniae, Escherichia coli, and Proteus mirabilis. In volunteers, satisfactory concentrations of Cefazolin in serum and urine were obtained after single intramuscular doses. The maximal concentration in serum at dosing of 500 mg was 44. 6 mcg/ml, which was about twice as high as that of Cephaloridine (17. 2 mcg/ml). The recovery rate of Cefazolin in the 24 hour urine was at 95.9% dosing of 250 mg and 82.4% at 500 mg which w ere also higher than that of Cephaloridine (70.2% at 500 mg). Therapeutically effective concentrat ions of Cefazolin in serum and urine were maintained as long as 10 hours after administration. Biliary excretion of Cefazolin in dogs revealed that 3.3% of the intramuscularly administered dose (20 mg/kg) was recovered in the 24 hour bile. This rate was similar to that of ampicillin, and was markedly higher than that of Cephaloridine or Cephalothin. In rats, Cefazolin was well distributed in the kidneys, liver, heart, spleen, and lungs when given in a dose of 20 mg/kg intramuscularly.
