Pharmacokinetics and drug-drug interaction between enalapril, enalaprilat and felodipine extended release (ER) in healthy subjects

// Dai Li 1, * , Sumei Xu 2, * , Yulu Wang 2 , Dan Li 1 , Xiaomin Li 1 , Jing Pan 1 and Pingsheng Xu 1 1 National Institution of Drug Clinical Trial, Xiangya Hospital, Central South University, Changsha 410008, China 2 Department of Pharmacy, Xiangya Hospital, Central South University, Changsha 410008, China * These authors have contributed equally to this work Correspondence to: Pingsheng Xu, email: xups2016@126.com Keywords: enalapril, enalaprilat, felodipine, interaction, pharmacokinetics Received: March 06, 2017     Accepted: July 18, 2017     Published: August 07, 2017 ABSTRACT Since angiotensin-converting enzyme (ACE) inhibitors and calcium antagonists have complimentary mechanisms of action, enalapril, an ACE inhibitor, is used in combination with felodipine, a vascular selective dihydropyridine calcium antagonist, for the treatment of hypertension. The present study was designed to investigate the possible drug-drug interaction between these two agents in Chinese healthy subjects. A randomized, open-label, multiple-dose, 3-treatment, 3-period, 6-sequence cross-over study enrolling 12 healthy subjects (six male and six female subjects) was performed. Plasma pharmacokinetic studies were performed after 5 mg of enalapril and 5 mg of felodipine were administered alone or concomitantly twice per day for six days, and once in the morning of day seven. All 12 healthy subjects (mean [SD] age, 24.3 [2.8] years; body weight, 57.3 [5.7] kg; height, 163.2 [5.2] cm) completed all scheduled pharmacokinetic studies. Geometric mean ratios (with 90% CIs) of AUC τ,ss and C max,ss for enalapril administered concomitantly with felodipine vs. enalapril administered alone were 1.025 (0.80-1.25) and 1.065 (0.70-1.43), respectively. Geometric mean ratios (with 90% CIs) of AUC τ,ss and C max,ss for felodipine administered concomitantly with enalapril vs. felodipine administered alone were 1.14 (0.97-1.31) and 0.80 (0.65-0.95), respectively. There were no severe or serious drug-related adverse events observed during the study. Our results revealed that the co-administration of enalapril and felodipine affected the pharmacokinetics of felodipine, but not that of enalapril. Although the difference in PK parameters was statistically significant, its clinical significance may be limited, considering safety profile observed in the present study.