Zudena 100 mg is a medication used in the treatment of erectile dysfunction (ED) in adult men. Its active ingredient is udenafil, which belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors. Udenafil works by inhibiting the enzyme phosphodiesterase type 5, which regulates blood flow to the penis. By inhibiting this enzyme, udenafil helps to increase blood flow to the penis during sexual stimulation, which leads to the achievement and maintenance of an erection. Zudena 100 mg is typically taken orally, with or without food, about 30 minutes to an hour before anticipated sexual activity. The onset of action may vary among individuals, but it is generally recommended to take the medication within this time frame for optimal effectiveness.