Simultaneous quantification of ramipril, glimepiride and metformin in human plasma by ultra-performance liquid chromatography - tandem mass spectrometry

Ramipril (RAM), glimepiride (GLM) and metformin (MET) are recently formulated together for the treatment of diabetes and cardiovascular disorders. This work introduces a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the simultaneous determination of the three drugs in human plasma after liquid-liquid extraction. This method made use of atorvastatin as internal standard (IS). Analytes were recovered from plasma by n-hexane: butanol (50:50%, v/v) and subsequently separated on Waters Acquity^TM UPLC BEH shield RP-C₁₈ column using methanol: water containing 0.1% formic acid (90: 10%, v/v) as a developing system. The calibration curves were linear (r² > 0.99) over a range of 0.1 - 1000 ng/mL for RAM & GLM and 250 - 2000 ng/mL for MET. The intra-day and inter-day precisions were below 14.32% and the accuracy was all within ±15%. Moreover, other validation parameters for the proposed method like matrix effect, selectivity, recovery and stability were adopted. The proposed method can be applied for the sensitive and selective quantification of the analytes in bioavailability and pharmacokinetics studies.