Estimation of Tolterodine using K3-EDTA in Human Plasma by HPLC/MS/MS

Abstract

A rapid, sensitive and reliable method was developed to quantitate tolterodine in human plasma using liquid chromatography–electrospray tandem mass spectrometry. The assay was based on liquid–liquid extraction of the compounds from plasma with dichloromethane: isopropyl alcohol: n-hexane (40:5:55,v/v/v) and hydrophilic interaction chromatography performed on a symmetry 15cm, 150×4.6mm, 5μ column. The mobile phase consisted of acetonitrile-10 mM ammonium formate pH 5.0 (65:35, v/v). Quantification was through positive-ion mode and selected reaction monitoring at m/z 326.2 → 147.2 for tolterodine and 332.2 → 153.2 for the internal standard tolterodine D6, respectively. The lower limit of quantitation was 25 pg/ml using 0.5 ml of plasma for the parent drug and linearity was observed up to 10.00-0.025ng/ml. Within-day and between-day precision expressed by relative standard deviation was less than 11% and inaccuracy did not exceed 7% at all levels. The assay was applied to the analysis of samples from a pharmacokinetic study.