A novel, simple, specific, sensitive and reproducible high-performance liquid 
chromatography assay method has been developed and validated for the estimation 
of Orteronel in rat plasma. The bioanalytical procedure involves extraction of 
Orteronel and phenacetin (internal standard) from rat plasma with a simple 
liquid-liquid extraction process. The chromatographic analysis was performed on 
a Waters Alliance system using a gradient mobile phase conditions at a flow rate 
of 1 mL/min and a C18 column maintained at ambient room temperature. The eluate 
was monitored using a photodiode array detector set at 242. Orteronel and 
internal standard eluted at 4.8 and 6.2 min, respectively and the total run time 
was 9 min. Method validation was performed as per US Food and Drug 
Administration guidelines and the results met the acceptance criteria. The 
calibration curve was linear over a concentration range of 100-3149 ng/mL (r(2) 
= 0.995). The intra- and inter-day precisions were in the ranges of 0.31-7.87 
and 3.97-6.35, respectively, in rat plasma. The validated HPLC method was 
successfully applied to a pharmacokinetic study of Orteronel in rats.