Viagra may face some tough competition as US Food and Drug Administration (FDA) approved Vivus’ Stendra (generic name Avanafil) to treat erectile dysfunction, in a statement released on April 27th.

"Patients and treating physicians continue to report significant dissatisfaction with current treatments of ED. We believe that the PDE5 selectivity and absorption profile of STENDRA make it an important new treatment option for many men with erectile dysfunction”, Peter Tam, the president of Vivus, said in a press release.

Unlike Viagra that takes about an hour to start working, Stendra takes about half that time and according to some reports as little as 15 minutes. This gives Stendra an edge over other competitors like Viagra, Cialis and Levitra.

“This approval expands the available treatment options to men experiencing erectile dysfunction, and enables patients, in consultation with their doctor, to choose the most appropriate treatment for their needs,” Victoria Kuslak deputy director of the Office of Drug Evaluation in the FDA’s Center for Drug Evaluation and Research said in a news release.

It is estimated that 30 million men in U.S suffer from erectile dysfunction.

Stendra belongs to a class of PDE5 inhibitors that are used to increase blood flow to penis. PDE5 inhibitors might cause blindness or hearing loss. Also, FDA advises men who take nitrates to avoid taking Stendra as it can cause sudden drop in blood pressure.

In clinical trials to test the efficacy, Stendra and a placebo were randomly assigned to 1,267 patients. The doses of Stendra given were 50 mg, 100 mg and 200 mg. the participants were asked to take the tablets 30 minutes before sexual activity. The test period was about 12 weeks after which patients were asked to fill in a questionnaire before the start of the test and every four weeks to evaluate the effects.

Results showed that there was improvement in erection, vaginal penetration and successful intercourse in patients who took Stendra compared to those on placebo.

The side effects of using Stendra included headache, redness of face, back-pain etc. The tests showed that the side-effects did not worsen further. Vivus recommends that Stendra should be taken only once in a day.