Pharmacokinetics of cefotaxime in the postpartum patient

A scarcity of pharmacokinetic data are available on cefotaxime in the obstetric patient. Fifteen patients received either 1 or 2 gm of cefotaxime after cesarean section. After intravenous administration of the designated dose, serial blood samples were analyzed for cefotaxime and its active metabolite, desacetyl cefotaxime (DCTX), by high-pressure liquid chromatography. The mean (+/- SD) peak concentrations of cefotaxime were 14.1 +/- 7.9 micrograms/ml and 40.0 +/- 32.5 micrograms/ml for the 1- and 2-gm dosage regimens, respectively. Detectable trough concentrations were 0.87 +/- 0.24 and 1.0 +/- 0.26, respectively, with many values falling below the sensitivity limits of the assay (0.5 micrograms/ml). The mean peak concentrations of DCTX for the two doses were 5.5 +/- 1.9 micrograms/ml and 10.9 +/- 6.2 micrograms/ml, respectively. Measurable trough levels for DCTX were more frequently identified, than for cefotaxime, at the end of the dosing interval due to an extended half-life as compared to its parent compound. Pharmacokinetic parameters of cefotaxime demonstrated large volumes of distribution and high clearance rates. Our data suggest altered pharmacokinetics of this agent in the obstetric patient when compared to previous studies in nonpregnant patients. This may be important in the seriously ill gravida where dosage adjustments in cefotaxime administration may be needed.