Plasma pharmacokinetics and urinary excretion of thalidomide after oral dosing in healthy male volunteers.

The plasma pharmacokinetics and urinary excretion of thalidomide have been evaluated in eight healthy male volunteers receiving a single oral dose of 200 mg. Concentrations of thalidomide were determined by a new HPLC assay. Plasma concentration vs. time data were well fit by a one-compartment model. The mean (+/- SD) peak concentration, 1.15 +/- 0.2 microgram/ml, was achieved at 4.39 +/- 1.27 hr. Absorption and elimination half-lives were 1.70 +/- 1.05 hr and 8.70 +/- 4.11 hr, respectively, with a lag time of 0.41 +/- 0.17 hr observed in six subjects. The apparent volume of distribution and total body clearance rate, based on assumed complete bioavailability, were 120.69 +/- 45.36 liters and 10.41 +/- 2.04 liters/hr. The urinary excretion of thalidomide accounted for only 0.6 +/- 0.22% of the total dose administered over 24 hr, and the renal clearance rate was 0.08 +/- 0.03 liter/hr. This suggests that the major route of elimination of thalidomide is nonrenal.