The objective of this research was to develop and validate a simple, sensitive and specific Liquid Chromatography –Tandem Mass Spectrometry (LC–MS/MS) quantification of Betahistine in human plasma using Betahistine-d4 as Internal Standard (IS). The analytical method consists of liquid-liquid extraction of plasma sample followed by the determination of Betahistine by a LC–MS/MS. The analyte was separated on a Zorbax Eclipse XDB -C18 (150 x 4.6 mm, 5 µ) column with an isocratic mobile phase of Acetontrile: 0.1% formic acid (80: 20 v/v) at a flow rate of 0.8 mL/min. The protonated ions were formed by a turbo ionspray in a positive mode was used to detect analyte and internal standard (IS). The MS/MS detection was made by monitoring the fragmentation of m/z 137.1→94.0 for Betahistine and m/z140.2→94.10 for internal standard on a mass spectrometer. The method was validated with the correlation coefficients of (r2)≥0.9997 over a linear concentration range of 10.00-501.20 pg/mL. This method demonstrated intra and inter-day precision within 1.1–1.6% and 0.2–0.54% and accuracy within 98.04-101.85% and 98.04–101.14% for BET.
