Determination of two HMG-CoA reductase inhibitors, pravastatin and pitavastatin, in plasma samples using liquid chromatography-tandem mass spectrometry for pharmaceutical study

We developed a method for determining pravastatin or pitavastatin, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, in plasma using liquid chromatography and tandem mass spectrometry (LC-MS/MS). Pravastatin, pitavastatin and the internal standard fluvastatin were extracted from plasma with solid-phase extraction columns and eluted with methanol. After drying the organic layer, the residue was reconstituted in mobile phase (acetonitrile:water, 90:10, v/v) and injected onto a reversed-phase C(18) column. The isocratic mobile phase was eluted at 0.2 mL/min. The ion transitions recorded in multiple reaction monitoring mode were m/z 423 --> 101, 420 --> 290 and 410 --> 348 for pravastatin, pitavastatin and fluvastatin, respectively. The coefficient of variation of the assay precision was less than 12.4%, the accuracy exceeded 89%. The limit of detection was 1 ng/mL for all analytes. This method was used to measure the plasma concentration of pitavastatin or pravastatin from healthy subjects after a single 4 mg oral dose of pitavastatin or 40 mg oral dose of pravastatin. This is a very simple, sensitive and accurate analytic method to determine the pharmacokinetic profiles of pitavastatin or pravastatiny.