Simultaneous Determination of a Fixed-Dose Combination of Lercanidipine and Valsartan in Human Plasma by LC–MS-MS: Application to a Pharmacokinetic Study

: A simple, sensitive and reproducible liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-MS-MS) method was developed and validated for the first time for simultaneous quantification of lercanidipine and valsartan in human plasma. The analytes were extracted by simple protein precipitation with acetonitrile and separated on a Hanbon Hedera ODS-2 C18 (150 mm× 2.1 mm, 5 μm) column. The mobile phase was composed of a mixture (53:47, v/v) of acetonitrile and 10 mmol/L ammonium acetate containing 0.5% formic acid. The analytes were ionized by positive electrospray ion and detected in the multi-reaction monitoring mode with m/z 612.1 → 280.2 for lercanidipine, m/z 436.0 → 235.1 for valsartan and m/z 285.1 → 193.1 for diazepam, the internal standard. The calibration curves obtained were linear over the concentration range of 0.01504-10.07 ng/mL for lercanidipine and 5.025-6,030 ng/mL for valsartan. The results of the intra- and inter-day precision studies were within the acceptance range. The recoveries of the analytes were in the range of 98-103%. This method was successfully applied to the pharmacokinetic study of a novel fixed-dose combination of lercanidipine and valsartan formulation after an oral administration to healthy Chinese subjects.