Pharmacokinetics of three-dose cefoxitin prophylaxis in caesarean section.

A pharmacokinetic analysis of cefoxitin in women undergoing caesarean section under general anaesthesia, was performed. In order to prevent infections postoperatively three doses of cefoxitin--2, 1 and 1 g, respectively--were given as a 3-min intravenous infusion at 6-h intervals. In vitro growth of most pathogens is inhibited at a cefoxitin concentration of 16 micrograms/ml. In the sera of the patients, this antibiotic level was maintained for a period of 90-100 min after the first administration (2 g) and 45-50 min after the second and the third administration of cefoxitin (1 g). The period of subinhibitory antibiotic concentrations lasted 270 and 315 min, respectively. How can one reach prolonged antibiotic coverage? In order to minimize antibiotic pressure on hospital flora it is advisable not to increase the total amount of antibiotic (4 g) administered. By starting a 310 mg/h infusion after the initial 2 g bolus injection, the serum concentration of cefoxitin can be maintained at a minimum level of 16 micrograms/ml during a period of 6.5 h. The improvement of antibiotic administration suggested requires further clinical testing.