Each subject will participate in two sessions in which they will be randomized to receive either 200 mg of avanafil or matching placebo for 9 days. On Day 3 of each period, subjects will receive a single dose of warfarin (25 mg). Following the warfarin dose, pharmacokinetic and pharmacodynamic sampling will be taken over a period of 7 days. Subjects will be discharged on Day 10 following the end-of-period evaluation. There will be a washout of at least 21 days between the warfarin doses. The study medications will be administered with 240 mL of water following an overnight fast of at least 10 hours.