Clinical Pharmacokinetics of Lorazepam. III. Intravenous Injection. Preliminary Results

Abstract

Four healthy male volunteers received 5 mg lorazepam as a single i.v. injection. Concentrations of lorazepam and its glucuronide metabolite were determined in multiple venous blood samples drawn during 48 h after dosing and in all urine collected during 96 h after the dose. Mean pharmacokinetic parameters for lorazepam were: apparent elimination half-life, 13.2 h, volume of distribution, 0.84 l/kg and total clearance, 55.3 ml/min. Lorazepam glucuronide, the major metabolic product of lorazepam, promptly appeared in blood, reached peak levels within 6 h of the dose, then declined in parallel with the parent compound. A mean of 69% of the dose was recovered in urine as lorazepam glucuronide.