Study to Compare the Effects of Viagra® Vs Hezkue® in Healthy Fasted Male Participants.

This is a Phase 1, open-label, single-center, two-way crossover study to evaluate the pharmacokinetics (PK), bioequivalence (BE), safety, and tolerability of ASP-001 (oral liquid suspension of sildenafil) compared to Viagra (sildenafil film-coated tablet) under fasted conditions in 56 healthy adult male participants. The study aims to demonstrate bioequivalence between the ASP-001 and Viagra formulations and to evaluate whether the absorption rate of ASP-001 is superior to that of Viagra. Additionally, the study assesses the tolerability of ASP-001, including potential for oral irritation, dizziness, or headache. Participants are randomized to one of these two sequences: * Sequence 1: ASP-001 in Period I, Viagra in Period II. * Sequence 2: Viagra in Period I, ASP-001 in Period II There is a washout period of 6 days between treatment periods. Enrollment may be increased at any point in this trial to ensure a minimum of 56 evaluable participants.