Udenafil, a PDE5 inhibitor that boosts blood flow to the penis to help attain and sustain an erection during sexual stimulation, is an ingredient in zudena pills, which are intended to treat erectile dysfunction (ED) in males. Zudena tablets, which are known for their rapid start and prolonged (up to 12 hours) effects, are usually taken 30 to 60 minutes prior to intercourse. To prevent possible adverse effects like headache, flushing, or dizziness, they should only be taken under medical supervision and only when sexually aroused.