[Pharmacokinetics of moxalactam in adults]

Specific characteristics of Moxalactam, a new beta-lactam antibiotic, are high serum concentrations, prolonged half-life and good tissular diffusion. After IM injection of a single dose of 0.25, 0.5 and 1 g, the maximum serum concentration, achieved at one hour, averages 13, 16-21 and 30-50 micrograms/ml. After rapid IV injection of 0.5 and 1 g, the average maximum serum concentrations are 90 and 150 micrograms/ml; after an IV infusion of 2 g over 20 minutes, maximum concentrations are 150 to 180 micrograms/ml. Moxalactam elimination kinetics are linear, independent from the dose and route of administration, with a distribution half-life (T 1/2 alpha) between 0.20 and 0.60 hours and an elimination half-life (T 1/2 beta) between 2 and 2.5 hours (range: 1.9 and 3.1 hours). The apparent distribution volume is between 15 and 18 liters, i.e. 20 to 25% of the body weight. Serum or total clearances and renal clearances are respectively 80 to 100 and 50 to 90 ml/mn, with wide variations from one author to another. Approximately 70 to 90% of the administered dose are eliminated in the urine over 24 hours, without any tubular secretion. Renal failure results in a progressive increase of the elimination half-life, which can reach 20 hours in patients with anuria; approximately 50% of the injected dose are recovered by hemodialysis. Many pharmacokinetic studies have demonstrated the excellent diffusion of the agent in the various tissues and body fluids, particularly in the CSF. From the collation of bacteriologic and pharmacokinetic data, dosage regimens adjusted to the renal function can be proposed.