Tadalafil works by increasing blood flow to the penis during sexual stimulation, helping men achieve and maintain an erection. It belongs to the same class of medications as sildenafil (Viagra), vardenafil (Levitra), and avanafil (Stendra), but tadalafil is known for its longer duration of action. Tadagra Prof 20 mg can provide effective relief from ED for up to 36 hours, allowing for more spontaneity in sexual activity compared to some other ED medications.