Pfizer Inc. on Monday said U.S. regulators approved the active ingredient in its impotence drug Viagra to treat pulmonary hypertension.

Sold under the name Revatio, the drug contains sildenafil citrate, the same active ingredient in Viagra.

Pulmonary hypertension is a rare condition in which the blood vessels that supply the lungs develop high blood pressure, Pfizer said.

The drug will compete with Swiss biotech company Actelion’s Tracleer.

How To Take Viagra
Viagra is taken by mouth as needed between four hours and one-half hour before sexual activity (about one hour before is most effective). Take viagra only as directed, usually once daily as needed. Sildenafil works along with sexual stimulation to help achieve an erection.

U.S. regulators said last week they had received reports of Blindness among patients taking Viagra and some rival impotence drugs. Pfizer said there is no proof the two are linked.

Viagra was originally designed to treat chest pain caused by clogged arteries but did not prove successful. Researchers then stumbled on its effectiveness for impotence.