Pharmacokinetic interpretation of blood levels and urinary excretion data for cefazolin and cephalothin after intravenous and intramuscular administration in humans.

Blood levels of cefazolin and cephalothin were determined in two separate crossover studies in 20 healthy male adults, each after intravenous and intramuscular administration. Pharmacokinetic parameters were calculated from the intravenous data based upon a two-compartment open model. The rate constants controlling the distribution between the central and peripheral compartments, the overall elimination rate constants, the apparent volumes of distribution, and the fraction of the dose in the central and peripheral compartments were determined. The bioavailability was calculated to be 100% for cefazolin and cephalothin.