HPLC-MS-MS for the Simultaneous Determination of Atorvastatin and Amlodipine in Plasma of Hypertensive Patients

Combination drug products containing amlodipine and atorvastatin are widely marketed and used in the treatment of concomitant hypertension and dyslipidemia. A rapid, simple and sensitive high performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method for determination of atorvastatin and amlodipine in plasma of hypertensive patients has been developed and validated to be used for therapeutic drug monitoring. The plasma samples were subjected to methanol protein precipitation. Chromatographic separation was performed on a C18 column using a gradient elution. The mobile phase consisted of 0.1% of formic acid in water and 0.1% of formic acid in acetonitrile and was pumped at a flow rate of 0.4 mL min(-1). Detection of analytes was achieved by tandem mass spectrometry with electrospray ionization (ESI) interface in positive ion mode. The calibration curves were linear over the range of 0.46-1,000 ng mL(-1). The intra- and inter-day precisions were within 12.2%, while the accuracy ranged from 92.7 to 108.1%. The validated LC-MS-MS method was successfully applied for the determination of atorvastatin and amlodipine in plasma of hypertensive patients.