Bioequivalence Study of Two Risedronate Sodium Film-Coated Tablet Formulations in Healthy Volunteers

The present study was performed to compare the bioavailability of 2 risedronate sodium 35 mg film-coated tablet formulations (test formulation and reference formulation). Prior to the present study, in vitro comparative dissolution test has been conducted for test and reference formulations. Dissolution profiles shown that more than 85% of the drug is dissolved within 15 min at pH 1.2, pH 4.5, and pH 6.8. This study was a randomized, single-blind, 2-period, 2-sequence cross-over study which included 48 evaluable healthy adult male and female subjects under fasting condition. In each of the 2 study periods (separated by a washout of 3 weeks) a single dose of test or reference drug was administered. The pharmacokinetic parameters assessed in this study were cumulative urinary excretion from drug administration to 72 h (Ae72h) and maximum urine excretion rate (dAe/dtmax). These parameters were determined from urine concentrations of risedronate and urine volume. Urinary concentrations of the drug were determined by high performance liquid chromatographic method with UV detector. The geometric mean ratios (90% CI) of the test drug/reference drug for risedronate were 106.60% (92.34–123.07%) for Ae72h and 104.75% (88.86–123.47%) for dA/dtmax. The geometric mean ratios calculated for Ae72h and dA/dtmax of risedronate were within the bioequivalence range (80.00–125.00% for Ae72h and dA/dtmax). It was concluded that the 2 risedronate sodium film-coated tablets (test and reference drugs) were bioequivalent.