Simultaneous ultraperformance liquid chromatography/tandem mass spectrometry determination of four antihypertensive drugs in human plasma using hydrophilic-lipophilic balanced reversed-phase sorbents sample preparation protocol

Therapeutic drug monitoring of angiotensin-converting enzyme inhibitors has a great impact on blood pressure control in patients with heart failure and hepatic and renal impairment. To provide an efficient tool for drug assessment in plasma, a UPLC-MS/MS method was developed for simultaneous determination of benazepril hydrochloride, fosinopril sodium, captopril and hydrochlorothiazide in human plasma samples. Solid phase extraction was applied for sample preparation using OASIS (R) hydrophilic- lipophilic balanced reversed-phase sorbents cartridges. Chromatographic separation was performed using an Agilent SB-C18 column and methanol-0.1% formic acid in water (95:5, v/v) as mobile phase, at flow rate 0.3 mL/min. Detection was accomplished using a tandem mass spectrometer. The method was validated according to US Food and Drug Administration guidelines. It showed good linearity over concentration ranges 5-400 ng/mL for benazepril hydrochloride, fosinopril sodium and hydrochlorothiazide and 100-3500 ng/mL for captopril. CV% values were <13.92% whereas the mean accuracy ranged from 94.50 to 113.82% for quality control samples and their extraction recoveries ranged from 90.60 to 99.38%. In conclusion, the present study revealed method selectivity and sensitivity; it can be applied for estimation of angiotensin converting enzyme inhibitors and hydrochlorothiazide in human plasma for dose adjustment and therapeutic drug monitoring.