Simultaneous determination of hydrochlorothiazide and valsartan in human plasma by liquid chromatography/tandem mass spectrometry

A rapid and specific liquid chromatography/tandem mass spectrometry method was described for the simultaneous determination of hydrochlorothiazide and valsartan in human plasma. After extracted from plasma using methanol, hydrochlorothiazide, valsartan and hydroflumethiazide, irbesartan, used as the internal standard, respectively, were chromatographically analyzed on a Phenomenex Kromasil C-8 column with water and methanol ( 27: 73, v/v) as the mobile phase. Selected reaction monitoring was specific for mass detection employing negative electrospray ionization. The calibration standards were linear over the concentration range (3.13-800 ng/ml for hydrochlorothiazide and 11.72-3000 ng/ml for valsartan). The method was found to be suitable for application to a pharmacokinetic study after oral administration of dispersible tablet containing 12.5mg hydrochlorothiazide and 80 mg valsartan to 20 healthy volunteers.