A rapid and specific approach for direct measurement of pravastatin concentration in plasma by LC-MS/MS employing solid-phase extraction.

A rapid, specific and sensitive LC-MS/MS assay using solid-phase extraction (SPE) for the determination of pravastatin, in human plasma is described. The plasma filtrate obtained after SPE, using a polymer base, a hydrophilic-lipophilic balance (HLB) cartridge, was submitted directly to short-column liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay, with negligible matrix effect on the analysis. For validation of the method, the recovery of the free analytes was compared with that from an optimized extraction method, and the analyte stability was examined under conditions mimicking the sample storage, handling, and analysis procedures. The extraction procedure yielded extremely clean extracts with a recovery of 107.44 and 98.93% for pravastatin and IS, respectively. The intra-assay and inter-assay precisions for the samples at the LLOQ were 3.30 and 7.31% respectively. The calibration curves were linear for the dynamic range 0.5-200 ng/mL with correlation coefficient r > or = 0.9988. The intra- and inter-assay accuracy ranged from 95.87 to 112.40%. The method is simple and reliable with a total run time of 3 min. This novel validated method was applied to the pharmacokinetic (PK) study in human volunteers receiving a single oral dose of 40 mg immediate release (IR) formulation. Copyright 2006 John Wiley & Sons, Ltd.