Usage: Viagra (Sildenafil citrate) is a drug used to treat erectile dysfunction (impotence) in males and pulmonary arterial hypertension (PAH). Sildenafil citrate, sold as Viagra, Sildenafil is an oral drug for the treatment of ED, used in the treatment of erectile dysfunction and premature ejaculation, erectile function impairment and premature ejaculation has very significant improvements. There are over 1500 documents …