A sensitive, rapid determination of moxonidine in plasma by LC-MS/MS, application to bioequivalence study

The objective of this work is to determine the plasma concentrations of Moxinidine by liquid chromatography coupled with triple quad mass spectrometer (LC-MS/MS) using internal method. Method development was conducted in such way that sufficient sensitivity achieved and no short term and long term matrix effects effect the method performance. Sensitivity found superior in positive ionization than negative ionization. Sum of multiple daughter ions were used as mass transactions for Moxonidine are 242.05/206.1 and 242.05/199.05 where as single mass transaction was used for Clonidine are 230.1/213.1. Chromatography was optimized using Acetonitrile: Buffer (10mmol Ammonium Acetate) (85:15) on Hypurity C8, 100 x 4.6 mm analytical column. Calibration curve found linear over the range 5.004 to 10345.023 pg/ml using 1/x2 as weighting factor. Method validation was conducted as per international method validation guidelines. The method is successfully applied to analyze 360 clinical study samples collected after administration of 25mg of Moxonidine in a IEC approved two phase clinical study. Incurred sample reanalysis was conducted and found method is reproducible.