Bioequivalence study of a newly developed oral solution of amlodipine and commercial tablets after single-dose administration in healthy volunteers

Objective: Amlodipine, a long-acting dihydropyridine calcium channel blocker, is frequently prescribed to pediatric patients. To date, no suitable pediatric formulation has been available. In this study, an amlodipine oral solution was developed and tested for bioequivalence to tablets in healthy adult volunteers.
Methods: This study was designed as an open-label, single-dose, twosequence, two-period, crossover trial to assess the bioequivalence of a newly developed amlodipine besylate oral solution 0.5 mg/mL compared to Norvasc® 5 mg tablets. 13 adult subjects were included and blood samples were collected for 72 hours. Amlodipine plasma levels were determined using a validated UPLC-MS/MS assay. Non-compartmental pharmacokinetic parameters were compared between the formulations according to European Medicines Agency (EMA) bioequivalence guidelines.
Results: The 90% confidence intervals of the test/reference ratios of the geometric means for the primary pharmacokinetic parameters AUC'0-72' and Cmax were within the acceptance range of 80.00-125.00% for bioequivalence. Mean (SD) AUC'0-72' was 102.7 (26.8) μg×h/L for the solution and 108.2 (30.6) μg×h/L for the tablet. Mean (SD) Cmax of the solution was 3.11(1.06) μg/L with a median (IQR) t-max of 4.0 hours. Mean (SD) Cmax of the tablet was 2.91 (0.84) μg/L with a median (IQR) tmax of 6.0 hours. Intrasubject coefficients of variation were 10.2% (AUC'0-72') and 12.4% (Cmax).
Conclusions: The formulations are bioequivalent according to EMA guidelines. This warrants further study of our novel amlodipine oral solution in pediatric patients.