Bioequivalence Studies of Sildenafil Citrate Orodispersible Film Administered with and without Water vs Viagra(Ⓡ) Film-Coated Tablets in Healthy Male Volunteers

BACKGROUND: Orodispersible film (ODF) formulation offers ease of use, convenience of administration, and other advantages, especially for patients who have difficulty in swallowing or are on liquid restriction compared with conventional oral formulations for the treatment of erectile dysfunction. OBJECTIVES: These studies compared the bioequivalence of 50 mg sildenafil citrate ODF formulation (test drug) with the marketed 50 mg sildenafil citrate film-coated tablet (FCT) (Viagra(Ⓡ); Pfizer, New York, NY) (reference drug), with and without water in 2 randomized cross-over studies. METHODS: Two randomized cross-over studies were conducted. The first study explored the bioequivalence of test drug administered with and without water compared with the reference drug with water. The second study investigated the bioequivalence of test drug, without water, compared with the reference drug with water. Forty-two and 80 healthy male volunteers were recruited in the first and second study, respectively. All volunteers fasted for 10 hours pre-dose. A 1-day washout period between doses was observed. Blood samples were collected at both before (up to 120 minutes before dosing) and after dosing (at different intervals up to 14 hours) stages. Statistical analyses on pharmacokinetic parameters were performed. Safety and tolerability for both the formulations were evaluated. RESULTS: In the first study, bioequivalence was demonstrated for sildenafil citrate ODF administered with water when compared with the Viagra(Ⓡ) FCT. The ratios of adjusted geometric means (90% confidence interval (CI)) were maximum plasma concentration: 1.02 (94.91–108.78) and area under the plasma concentration-time curve: 1.09 (104.49–113.21) for sildenafil citrate ODF administered with water vs Viagra(Ⓡ) FCT. These ratios were within the bioequivalence acceptance range of 80% to 125%, indicating that the bioequivalence criteria were met. The pharmacokinetic parameters for the second study also showed bioequivalence for sildenafil citrate ODF (without water) compared with Viagra(Ⓡ) FCT. The ratios of adjusted geometric means (90% CI) were maximum plasma concentration: 1.02 (95.47–109.36) and area under the plasma concentration-time curve: 1.06 (103.42–108.40) for sildenafil citrate ODF administered without water vs Viagra(Ⓡ) FCT. Adverse events in both the studies occurred at similar rates for the 2 formulations and were mild in intensity. CONCLUSIONS: These results suggest that the new ODF formulation can be used interchangeably with the marketed FCT formulation. Sildenafil citrate ODF administered with and without water met bioequivalence criteria compared with Viagra(Ⓡ) FCT administered with water under fasted conditions in healthy adult male volunteers. The new ODF formulation can be used as a suitable alternative to the conventional oral solid dosage form.