Relative Bioavailability of Fixed-Dose Combinations of Tamsulosin and Dutasteride: Results From 2 Randomized Trials in Healthy Male Volunteers

The relative bioavailabilities of dutasteride/tamsulosin hydrochloride 0.5 mg/0.2 mg fixed-dose combination (FDC) capsules compared with coadministered reference products (1 dutasteride 0.5-mg capsule [Avodart (R)] + 1 tamsulosin hydrochloride 0.2-mg orally disintegrating tablet [Harnal D (R)]) were investigated in 2 clinical trials under fasted and fed conditions (ClinicalTrials.gov NCT02184585 and NCT02509104). Both trials were open-label, randomized, single-dose, crossover studies in healthy male adults aged 18-65 years. Trial 1 evaluated 2 formulations (FDC1 and FDC2), and trial 2 evaluated a third formulation (FDC3). The primary end points were dutasteride area under the concentration-time curve from time 0 to t (AUC((0-t))) and peak plasma concentration (C-max) and tamsulosin AUC((0-infinity)), AUC((0-t)), and C-max. The formulations were considered to be bioequivalent if the 90%CIs for the geometric mean ratios for each end point were within the range of 0.80-1.25. For FDC1 in trial 1, bioequivalence criteria were not met for dutasteride C-max or AUC in the fasted state or for tamsulosin C-max in the fasted or fed states. For FDC2 in trial 1, all bioequivalence criteria were met except for tamsulosin C-max in the fasted state. For FDC3 in trial 2, bioequivalence criteria were met for all dutasteride and tamsulosin end points in both the fed and fasted states. Safety profiles were similar for all FDC formulations and combination treatments.