PT  - JOURNAL ARTICLE
AU  - Deepak Dalvie
AU  - Weichao Chen
AU  - Chenghong Zhang
AU  - Alfin D. Vaz
AU  - Teresa A. Smolarek
AU  - Loretta M. Cox
AU  - Jian Lin
AU  - R. Scott Obach
TI  - Pharmacokinetics, Metabolism, and Excretion of Torcetrapib, a Cholesteryl Ester Transfer Protein Inhibitor, in Humans
AID  - 10.1124/dmd.108.023176
DP  - 2008 Nov 01
TA  - Drug Metabolism and Disposition
PG  - 2185--2198
VI  - 36
IP  - 11
4099  - http://dmd.aspetjournals.org/content/36/11/2185.short
4100  - http://dmd.aspetjournals.org/content/36/11/2185.full
SO  - Drug Metab Dispos2008 Nov 01; 36
AB  - The pharmacokinetics, metabolism, and excretion of torcetrapib, a selective inhibitor of human cholesteryl ester transfer protein, were investigated in healthy human male volunteers after oral administration of [14C]torcetrapib (120-mg dose). The total mean recovery of radiolabeled dose after 21 days was 75.7%, and most of the dose (63%) was excreted in the urine. The total circulating radioactivity and unchanged torcetrapib plasma concentrations increased over the first 6 h and then declined slowly with mean terminal elimination half-lives of 373 and 211 h. Metabolism of torcetrapib was extensive in humans. Only 5.2% of the total dose constituted unchanged torcetrapib in the feces, whereas no parent was excreted unchanged in the urine. Similarly, pharmacokinetic analysis of total radioactivity and unchanged torcetrapib revealed that the area under the concentration versus time curve from zero to infinity of torcetrapib accounted for ∼7.0% of the circulating radioactivity. Torcetrapib was metabolized to numerous metabolites via oxidation. The primary metabolic pathway involved initial oxidative decarbamoylation followed by extensive further oxidation, resulting in the formation of bistrifluoromethylbenzoic acid (M1) and quinaldic acid (M4) metabolites. A mean 40% of the total dose was excreted in the urine as M4 (and its glucuronide and urea conjugates), whereas 7.0% of the total dose was excreted as M1. In vitro studies using human subcellular fractions suggested that the initial metabolism of torcetrapib proceeds via CYP3A-mediated decarbamoylation. Subsequent oxidations lead to the major circulating and excretory metabolites M1 and M4. The American Society for Pharmacology and Experimental Therapeutics