Pharmacokinetic Study of Cefmenoxime (SCE 1365-CMX) in Healthy Adults

Cefmenoxime pharmacokinetics were investigated in six healthy volunteers after intravenous and intramuscular administration of 0.5, 1, and 2 g. Blood and urine samples were analyzed by reversedphase high-pressure liquid chromatography using ultraviolet detection at 275 nm. The assay is precise and linear up to 200 µg/ml−1, with µg/ml−1 as the limit of detection. Linearity of cefmenoxime kinetics was demonstrated because the area under the plasma concentrations is proportional to studied doses. Eight hours after 1 g of cefmenoxime intramuscularly, mean plasma concentrations are, respectively, 0.6 ± 0.1 and 0.3 ± 0.1 µg/ml−1. Intramuscular Cefmenoxime is rapidly absorbed (Ka = 7.28 hours−1) with complete bioavailability (F = 0.99); apparent volume of distribution is 0.35 liters/kg−1 and elimination half-life 1.5 hours. The fraction of Cefmenoxime excreted unchanged in the urine after intramuscular administration is 0.72, indicating a major contribution of renal clearance in total clearance. Experimental data after intramuscular administration were well fitted with a two-compartment model.