Simultaneous quantitation of IC87114, roflumilast and its active metabolite roflumilast N-oxide in plasma by LC-MS/MS: application for a pharmacokinetic study

A sensitive and reliable high-performance liquid chromatographymass spectrometry (LCMS/MS) was developed and validated for simultaneous quantification IC87114, roflumilast (RFM), and its active metabolite roflumilast N-oxide (RFN) using tolbutamide as an internal standard. The analytes were extracted by using liquidliquid extraction and separated on a reverse phase C18 column (50?mm?x?3?mm i.d., 4.6?mu) using methanol: 2?mM ammonium acetate buffer, pH 4.0 as mobile phase at a flow rate 1?mL/min in gradient mode. Selective reaction monitoring was performed using the transitions m/z 398.3?>?145.9, 403.1 >186.9, 419.1?>?187.0 and 271.1?>?155.0 to quantify quantification IC87114, RFM, RFN and tolbutamide, respectively. The method was validated over the concentration range of 0.160?ng.mL-1 for RFM and RFN and 6 to 2980?ng.mL-1 for IC87114. Intra- and inter-day accuracy and precision of validated method were within the acceptable limits of?<15% at all concentrations. Coefficients of correlation (r2) for the calibration curves were >0.99 for all analytes. The quantitation method was successfully applied for simultaneous estimation of IC87114, RFM and RFN in a pharmacokinetic drugdrug interaction study in Wistar rats. Copyright (c) 2012 John Wiley & Sons, Ltd.