Simple and Rapid Method by Ultra High-Performance Liquid Chromatography (UHPLC) with Ultraviolet Detection for Determination of Efavirenz in Plasma: Application in a Preclinical Pharmacokinetic Study.

Abstract

A simple and rapid ultra-high-performance liquid chromatography (UHPLC) method for determination of efavirenz (EFV) in plasma was developed and applied in a preclinical pharmacokinetic study. The method involves only addition of acetonitrile to precipitation of plasma proteins followed by solvent evaporation. The mobile phase consisted of methanol, acetonitrile and 0.1M formic acid (20:50:30) at a flow rate of 0.3mL/min with run time of 5min. A CSH C18 column and a UHPLC-UV system operating at 245nm were used. There was a linear response in the range of 0.078 to 10μg/mL, and the equation was obtained by weighting (1/x2) with r2=0.9965. The pharmacokinetic disposition of EFV was investigated in rabbits (two groups, n=7) following a single intravenous administration (IV group) at a dose of 2.7mg/kg and a single oral administration (oral group) of EFV co-administered with lamivudine (3TC) and tenofovir (TNF) at a dose of 50, 25 and 25mg, respectively. The study demonstrated the applicability of the method for determination of EFV in plasma without interference from other co-administered drugs, and the pharmacokinetic parameters were calculated. The method showed advantages over other methods in the literature, such as simplicity of sample processing and fast results.