Bioequivalence and Bioavailability of an Orodispersible Tablet of Sildenafil Citrate in Healthy Chinese Male Subjects.

Sildenafil citrate is approved to treat erectile dysfunction. An orally disintegrating tablet (ODT) of sildenafil citrate that does not require swallowing or administration with fluids has been developed. The bioequivalence and bioavailability of sildenafil citrate ODT (50 mg) without and with water were compared with conventional sildenafil citrate tablets (50 mg) in an open-label, randomized crossover study. Healthy Chinese male subjects (n = 36) were allocated to 1 of 6 sildenafil citrate treatment sequences under fasted conditions, and plasma samples for determination of sildenafil concentrations were collected predose through 14 hours postdose. Bioequivalence was demonstrated for sildenafil citrate ODT administered without water relative to the sildenafil citrate tablet administered with water; 90%CIs for the ratios of adjusted geometric means for sildenafil AUC(last), C-max, and AUC(inf) (ratio, 101.41%; 90%CI, 95.49%-107.70%; ratio, 93.55%; 90%CI, 84.15%-104.00%; and ratio, 101.03%; 90%CI, 94.80%-107.66%; respectively) were wholly contained within the bioequivalence acceptance range of 80% to 125%, indicating bioequivalence criteria were met. Relative bioavailability of sildenafil citrate ODT administered with water to the sildenafil citrate tablet (50 mg) administered with water was 97.10%, 91.43%, and 97.09% with respect to sildenafil AUC(last), C-max, and AUC(inf), respectively (90%CI, 91.43%-03.12%, 82.25%-101.65%, and 90.90%-103.71%, respectively). Both sildenafil citrate formulations were generally well tolerated in healthy Chinese men. Sildenafil citrate ODT administered without or with water was bioequivalent to or met bioequivalence criteria compared with conventional sildenafil citrate tablets administered with water under fasted conditions in healthy Chinese men, thus offering a convenient alternative method of oral administration.