Pharmacokinetic studies of azlocillin, mezlocillin, cephalothin and sisomicin in rabbits.

Pharmacokinetic parameters of two new acylureido penicillins (azlocillin and mezlocillin) and of cephalothin and sisomicin were compared in rabbits after the subcutaneous administration of 50 mg or 100 mg. It was found that the highest serum level of the antibiotics was reached 15 to 30 min after administration. Only sisomicin, applied in a higher dosage, reached its peak value after 60 min. The half-lives for azlocillin and mezlocillin were 1.35 h and 1.38 h, respectively. The half-lives for cephalothin and sisomicin were 0.65 h and 5.7 h, respectively.