Pharmacokinetics of d(+)-usnic acid in rabbits after intravenous administration.

The pharmacokinetics of usnic acid, a lichen antitubercular, antitumor and enzyme inhibiting agent, was studied in normal male rabbits after administration of 5 mg/kg dose by intravenous route. Plasma samples were collected up to 48 h. The plasma usnic acid levels showed a triexponential decay with a terminal half life of 10.69 h. The mean volume of distribution of the central compartment was 43.93 ml/kg. The pharmacokinetic parameters obtained from a three-compartment body model and a noncompartment body model gave close values. The mean steady-state volume of distribution was 167.17 and 163.29 ml/kg, systemic clearance was 12.17 and 12.25 ml/h/kg and AUC was 428.51 and 426.69 micrograms.ml/h following three-compartmental and noncompartmental analyses respectively.