Pharmacokinetics of a Novel Orodispersible Tablet of Sildenafil in Healthy Subjects

Background Sildenafil citrate is indicated for the treatment of erectile dysfunction. An orally disintegrating tablet (ODT) of sildenafil citrate has been developed for the benefit of patients who have difficulty swallowing solid dosage forms. Objective The main goal of this study was to evaluate the bioequivalence of sildenafil ODT with and without water versus marketed sildenafil oral film-coated tablets. A secondary objective was to evaluate the effects of a high-fat meal on the pharmacokinetics of sildenafil ODT. Methods The bioequivalence study of sildenafil ODT given with and without water versus marketed sildenafil citrate film-coated oral tablets was conducted in 36 subjects. In a food-effect study, the effect of a standard high-fat meal on the pharmacokinetics of sildenafil ODT was evaluated in 12 subjects. Both studies were randomized, open-label, crossover, single-dose (50 mg) studies in healthy men aged ≥45 years. Plasma samples were collected for 14 hours postdose, and pharmacokinetics were determined by using noncompartmental analyses. Results All subjects in both studies were Asian males between the ages of 45 and 69 years. Sildenafil ODT without water was bioequivalent to the marketed sildenafil film-coated oral tablet as the 90% CI for the ratio of geometric means of Cmax, AUC0–∞, and AUC0–last were contained within equivalence limits (80%–125%). When sildenafil ODTs were given with water, the 90% CIs for sildenafil AUC0–∞ and AUC0–last were contained within the range of 80% to 125%; however, the 90% CI for sildenafil Cmax was not (79.76–92.78). This difference in Cmax is unlikely to have any clinically meaningful impact. High-fat meals reduced the rate but not the extent of absorption of sildenafil. Mean Cmax was reduced by 59%, and median Tmax was delayed from 0.625 hour (fasting) to 4 hours (high-fat meal). However, AUC values were comparable between fed and fasted treatments. Conclusions Sildenafil ODT, given with or without water, provides equivalent systemic exposure compared with marketed sildenafil film-coated oral tablets, thus offering a convenient alternative method of administration. Considering the results of the food-effect study, sildenafil ODT should be taken on an empty stomach. ClinicalTrials.gov identifiers: NCT01254383 (bioequivalence) and NCT01254396 (food effect).