Pharmacokinetics of the acyclureidopenicillins piperacillin and mezlocillin in the postpartum patient.

The postpartum patient experiences numerous physiologic alterations, which may affect the pharmacokinetics of certain drugs. Six patients received either piperacillin or mezlocillin intravenously immediately after delivery. Serum half-life and clearance were, respectively, 82.4 min and 202 +/- 105 ml/min for mezlocillin and 32.9 min and 456 +/- 88 ml/min for piperacillin. The data revealed that mezlocillin and piperacillin have significantly different pharmacokinetic reactions in the postpartum patient at the doses used.