This study investigates safety and pharmacokinetic comparison of Seoul Pharma's orally disintegrating film (ODF) formulation of sildenafil (test formulation) and Pfizer's "Viagra® (sildenafil)" Film Coated Tablet (FCT) formulation (reference formulation) in healthy volunteers.

• Background: An orally disintegrating film (ODF) formulation of sildenafil was recently developed in Korea. This formulation is expected to enhance the dosing convenience and increase patient compliance while yielding pharmacokinetic profiles comparable to the conventional film coated tablet (FCT) formulation.
• Objective: The goal of present study is to compare the pharmacokinetic (PK) profiles of a newly developed ODF formulation with a FCT formulation of sildenafil in healthy Korean male volunteers.
• Methods: This is a randomized, open-label, 2-period cross-over, single-dose study conducted in 2 parts. Eligible subjects were healthy male volunteers between the ages of 20 and 50 years and within 20% of their ideal body weight, and are equally divided into parts 1 and 2. Each subject will be received a single -dose of ODF and FCT formulations of sildenafil orally in a fasted state (part 1, 50mg; part 2, 100mg), with a 7-day washout period between the formulations. Blood samples are collected up to 24 hours. Pharmacokinetic parameters are determined for sildenafil and its active metabolite (N-desmethyl sildenafil). Adverse events will be also evaluated based on subject interviews and physical examinations.

Inclusion Criteria:

• Eligible subjects were healthy male volunteers between the ages of 20 and 50 years and within 20% of their ideal body weight, and
• With no congenital abnormality or chronic disease.

Exclusion Criteria:

Key exclusion criteria included:

• history of cardiovascular, pulmonary, renal, endogenous, gastrointestinal, hematologic, neurologic, or hemorrhagic disease;
• anatomical abnormality of penis or factors that cause priapism (e.g., sicklemia, multiple myeloma, leukemia);
• clinically significant findings on routine laboratory (serology, hematology, serum chemistry, and urinalysis), ECG or color blindness tests [8, 16];
• history of hypersensitivity reaction to PDE5 inhibitor including sildenafil;
• use of prescription drugs within 14 days before the study that had the potential to interact with the study medication; and
• use of any substance that could induce or inhibit cytochrome P450 3A4 synthesis (eg, St. John's wort, other herbal medications).