Penegra 100 mg is a medication containing sildenafil citrate, which is primarily used to treat erectile dysfunction (ED) in men. Sildenafil citrate belongs to a class of medications called phosphodiesterase type 5 (PDE5) inhibitors, which work by increasing blood flow to the penis during sexual stimulation, thereby helping to achieve and maintain an erection. Penegra 100 mg tablets typically contain a standard dose of sildenafil citrate. It is taken orally with water, usually about 30 minutes to 1 hour before anticipated sexual activity. Sildenafil citrate works by inhibiting the enzyme phosphodiesterase type 5 (PDE5), which regulates blood flow in the penis. By blocking PDE5, sildenafil citrate allows for increased blood flow, leading to improved erectile function.