Abstract
A rapid, simple, sensitive and specific LCโMS/MS method has been developed and validated for the simultaneous estimation of atorvastatin (ATO), amlodipine (AML), ramipril (RAM) and benazepril (BEN) using nevirapine as an internal standard (IS). The APIโ4000 LCโMS/MS was operated under the multipleโreaction monitoring mode using electrospray ionization. Analytes and IS were extracted from plasma by simple liquidโliquid extraction technique using ethyl acetate. The reconstituted samples were chromatographed on C~18~ column by pumping 0.1% formic acidโacetonitrile (15:85, v/v) at a flow rate of 1โmL/min. A detailed validation of the method was performed as per the FDA guidelines and the standard curves were found to be linear in the range of 0.26โ210โng/mL for ATO; 0.05โ20.5โng/mL for AML; 0.25โ208โng/mL for RAM and 0.74โ607โng/mL for BEN with mean correlation coefficient of โฅ0.99 for each analyte. The intraโday and interโday precision and accuracy results were well with in the acceptable limits. A run time of 2.5โmin for each sample made it possible to analyze more than 400 human plasma samples per day. The developed assay method was successfully applied to a pharmacokinetic study in human male volunteers. Copyright ยฉ 2010 John Wiley & Sons, Ltd.