Rapid high‐performance liquid chromatography–tandem mass spectrometry method for simultaneous measurement of venlafaxine and O‐desmethylvenlafaxine in human plasma and its application in comparative bioavailability study

Abstract

A rapid high-performance liquid chromatography-tandem mass spectrometry method has been developed and validated for simultaneous measurement of venlafaxine and O-desmethylvenlafaxine in human plasma using fluoxetine as an internal standard. In the liquid-liquid extraction method, compounds and internal standard were extracted from plasma using methyl tertiary butyl ether as an extraction solvent. The HPLC separation of the analytes was performed on a Zorbax SB-C(18), 50 x 4.6 mm, 5 microm column, using a isocratic elution program using a mobile phase consisting of HPLC-grade methanol: 5 mm ammonium acetate (80:20 v/v) at a flow-rate of 1.0 mL/min with a total runtime of 3.0 min. The proposed method has been validated with a linear range of 4-400 ng/mL for venlafaxine and 5-500 ng/mL for O-desmethyl venlafaxine. The method was applied for a bio-equivalence study of 75 mg tablets formulation in 32 Indian male healthy subjects under fasting conditions.