Rapid and sensitive assay for trantinterol, a novel beta(2)-adrenoceptor agonist, in human plasma using liquid chromatography-tandem mass spectrometry

A rapid and sensitive assay for trantinterol, a novel beta(2)-adrenoceptor agonist, in human plasma has been developed. Samples containing the analyte and internal standard, clenbuterol, were analyzed by liquid chromatography-tandem mass spectrometry after liquid-liquid extraction with diethyl ether:dichloromethane (60:40, v/v). Separation was performed on a Venusil MP C(18) column (50 mm x 4.6 mm, 5 microm) using methanol:1% formic acid (50:50, v/v) as mobile phase and monitored by multiple reaction monitoring of the precursor-to-product ion transitions of trantinterol at m/z 311.2-->238.1 and clenbuterol at m/z 277.2 --> 203.1. The total run time was only 1.5 min and the method was linear over the concentration range 1-1000 pg/mL with a lower limit of quantitation of 1 pg/mL. Intra- and inter-day precisions (relative standard deviation) were below 7% and 12%, respectively, with accuracy (relative error) below 8%. The method was successfully applied to a pharmacokinetic study involving oral administration of a 50 microg trantinterol tablet to healthy volunteers.