Cross-over study of the pharmacokinetics of cefonicid administered intravenously or intramuscularly to healthy adult humans.

The pharmacokinetics of cefonicid were investigated in eight healthy adults. A one-gram dose was administered either intramuscularly or intravenously in a cross-over design study. Mean peak cefonicid plasma concentrations of 186 to 204 mcg/ml and 88 to 123 mcg/ml were achieved after intravenous and intramuscular injection, respectively, with elimination half-lives of 4.9 h and 5.3 h. Cefonicid concentrations were measured by both microbiological (M.A.) and high-performance liquid chromatography (HPLC) assays. Results were quite similar with the two techniques, except for the urinary recovery of cefonicid in the first 24 hours (83% of the dose with MA - vs 53% with HPLC method). The apparent volume of distribution (Vd area) was 0.18 1/kg; the total body clearance (CT) and the renal clearance (CR) were 24-26 ml/min and 15-19 ml/min, respectively. The kinetic data of cefonicid were not significantly different for the two routes of administration. A one-gram i.v. or i.m. cefonicid dose produced high and prolonged plasma concentrations with a longer half-life than obtained with commonly used cephalosporins.