Bioequivalence of the pharmacokinetics between two formulations of 0.2 mg tamsulosin hydrochloride in healthy subjects

Tamsulosin is an effective therapeutic option for lower urinary tract symptoms, as it selectively blocks α1A- and α1D-adrenoceptors in the bladder and prostate. The purpose of this study was to evaluate the bioequivalence in the pharmacokinetics (PK) of two 0.2 mg tamsulosin formulations when administered as the reference formulation (Yuropa® sustained-release tablet) vs. the test formulation (Yutanal® capsule) in healthy male subjects. A randomized, open-label, single-dose, twoway, two-period, crossover study was conducted in 37 healthy volunteers. The 0.2 mg of tamsulosin as the test or the reference formulation were administered during each period, and serial blood samples were collected up to 36 hours after dosing for PK analyses. A non-compartmental analysis was used to estimate the PK parameters. Geometric mean ratios (GMR) and 90% confidence intervals (CIs) were calculated for the two formulations to compare the maximum concentration (C_max) and the area under the concentration-time curve from time zero to the time of the last quantifiable concentration (AUClast). The mean C_max and AUC_last for the test formulation were 6.19 μg/L and 71.30 μg.h/L, respectively, and 5.76 μg/L and 70.38 μg.h /L for the reference formulation, respectively. The GMRs (90% CIs) of the C_max and AUC_last between the two formulations were 1.09 (1.01–1.17) and 1.03 (0.96–1.10), respectively. Tamsulosin 0.2 mg as the test formulation exhibited bioequivalent PK profiles to those of the reference formulation. Therefore, the test formulation is expected to be an alternative to the reference formulation without concerns about differences in drug exposure.