Bioequivalence Study of Two Formulations of Flunarizine Hydrochloride Capsules in Healthy Chinese Subjects Under Fasting and Fed Conditions.

BACKGROUND AND OBJECTIVES

Flunarizine, a selective calcium channel blocker with vasodilatory and neuroprotective effects, is a mainstay for migraine prophylaxis and vertigo management. This study aimed to compare the bioequivalence, pharmacokinetics, and safety of test and reference flunarizine hydrochloride capsules after a single oral dose under fasting/fed conditions.

METHODS

A randomized, open-label, two-formulation, single-dose, two-period crossover bioequivalence study was conducted under fasting and fed conditions. Eligible healthy Chinese subjects received a single 5-mg dose of the test or reference flunarizine hydrochloride capsules, followed by a 21-day washout interval between periods. Blood samples were collected up to 36 h post-dose. Pharmacokinetic parameters were calculated using noncompartmental methods, and bioequivalence was assessed via geometric mean ratios of the test/reference for primary pharmacokinetic parameters, along with 90% confidence intervals. Tolerability was evaluated during the entire study period.

RESULTS

Twenty-four volunteers completed the fasting study, while 42 volunteers completed the fed study. The test formulation demonstrated bioequivalence to the marketed formulation, with 90% confidence intervals for geometric mean ratios of peak plasma concentration (fasting: 97.38-106.57%; fed: 92.71-109.58%), area under the curve from time 0 to 36 h (fasting: 98.20-108.09%; fed: 93.79-100.81%), and AUC from time 0 to infinity (fasting: 97.88-107.30%; fed: 93.63-100.53%), all within equivalence limits of 80.00-125.00%. High-fat meals delayed the time to maximum concentration by 2.5 h and increased exposure by 20%. Both the test and reference formulations were well tolerated, and no serious adverse events related to the study drug were reported during the study.

CONCLUSIONS

This study confirmed that test and reference flunarizine hydrochloride capsules were bioequivalent under fasting and fed conditions.

CLINICAL TRIAL REGISTRATION

ChiCTR1900026713.