Molecular modeling, spectrofluorimetric, and tandem mass spectrometric analysis reveal a competitive binding of amlodipine and rosuvastatin to plasma albumin: Insight into drug-drug interaction

Abstract

Hyperlipidemia and hypertension are common co-morbidities and considerably increase the risk of cardiovascular complications. The combined treatment has been recommended for decades; the lipid-lowering agents, statins, and calcium channel blockers (CCBs) are commonly prescribed to control the situation. Hence, the development of sensitive assay is of great importance for pharmacokinetic and therapeutic drug monitoring of the combined drugs. Herein, simple and robust chromatography-electrospray ionization-tandem mass spectrometry LC-ESI/MS) method for simultaneous determination of rosuvastatin (ROS) and amlodipine (AML) in rat plasma was developed and fully validated using irbesartan (IRB) as an internal standard (IS). Specimen preparation involved acetonitrile (ACN)-induce protein precipitation followed by gradient elution using 6 mM ammonium formate plus 0.1% formic acid and ACN at a flow rate of 0.4 mL min−1on an Agilent Eclipse Plus ODS (4.6 × 100 mm, 3.5 μm) column. Multiple reaction monitoring in positive ion mode was used for quantitation of precursor ion production at m/z 409.2 → 294.1 & 238.2 for AML, 482.1 → 258.1 for ROS, and 492.1 → 206.9 for IRB. Linearity was observed in the range of 1–5000 ng mL−1 for AML and 1–10,000 ng mL−1 for ROS with detection limits (S/N of 3) of 0.09 and 0.07 ng mL−1 for AML and ROS, respectively. No interference from endogenous substances was detected. The developed method was validated in terms of accuracy, precision, selectivity, recovery, matrix effects, and stability as per US-FDA Bioanalytical guidelines and successfully applied to clinical pharmacokinetic and drug-drug interaction (DDI) studies with a single oral administration of AML and ROS in rat plasma. The peak plasma concentrations (Cmax), area under the concentration-time curve (AUC), and volume of distribution (Vd) of AML was significantly influenced by the co-administration of ROS and vice versa. The data obtained from molecular modeling and spectrofluorimetric studies indicated that AML and ROS are competitively bound to plasma albumin. AML and ROS quenched the intrinsic fluorescence of human serum albumin owing to their binding nearest to tryptophan 214 within the hydrophobic pocket. A potential DDI in cardiovascular complicated patients receiving chronic treatment with AML and ROS thus deserves further attention and study to improve drug therapy and prevent serious side effects.