The absorption, distribution, metabolism and elimination of bevirimat in rats.

Panacos Pharmaceuticals, Inc., 209 Perry Parkway, Unit 7, Gaithersburg MD 20877, USA. pbullock@panacos.com

Bevirimat is the first drug in the class of maturation inhibitors, which treat HIV infection by disrupting the activity of HIV protease enzyme with a mechanism of action distinct from that of conventional protease inhibitors. The absorption, distribution, metabolism and elimination characteristics of single intravenous (25 mg/kg) and oral (25 mg/kg and 600 mg/kg) doses of 14C-bevirimat were studied in male Sprague Dawley and Long Evans rats. Pharmacokinetic and mass-balance studies revealed that bevirimat was cleared rapidly (within 12-24 h) after dosing, although plasma radioactivity was quantifiable up to 168 h. Radioactive metabolites of bevirimat were responsible for approximately 60-80% of plasma radioactivity. Systemically available bevirimat was predominantly (97%) excreted via bile in the faeces, with <or=1% of the dose excreted renally. Less than 0.1% of the dose was excreted in expired air. Quantitative whole-body autoradiography detected high quantities of radioactivity in the bile and liver soon after intravenous dose administration, and evidence of biliary excretion present during the 8 h following oral dosing. Oral bioavailability for the 25 mg/kg dose of bevirimat was estimated at 22-24% by pharmacokinetic and mass-balance methods, with bioavailability decreasing disproportionately with increasing dose for the 600 mg/kg group. Copyright (c) 2008 John Wiley & Sons, Ltd.

PMID: 18615840 [PubMed - indexed for MEDLINE]