Quantification of Etravirine in Rat Plasma by LC-MS/MS and Application to a Pharmacokinetic Study

A rapid, rugged and reproducible, higher in sensitivity bio-analytical method was developed for quantification of Etravirine (EV) in rat plasma by LC-MS/MS. Etravirine15N2, 13C1 (EVIS) used as an internal standard (IS). Chromatography was performed with ZORBAX Eclipse Plus Phenyl-Hexyl (50 mm × 2.1 mm × 3.5 mm) analytical column. Mobile phase was composed with 0.1% formic acid: acetonitrile (45:55 v/v), at a flow rate of 0.3 ml/min. Product ions of EV (163.1) and EVIS (166.1) were formed from the parent ion of EV (436.1) and EVIS (440.1). The drug and the IS were extracted from Liquid-liquid extraction (LLE) method. The calibration range is 5.0–750.0 ng/ml with a coefficient of determination (R2) is greater than 0.9950. This method demonstrated intra and inter day precision within 1.38 – 2.26% and 1.32–2.75%, and an accuracy within 99.77 – 100.80%, and 99.50 – 102.15%. Stability of EV in rat plasma was proved for freeze-thaw cycles, benchtop, and long term and Autosampler conditions. Pharmacokinetics study was studied in 6 healthy rats.