The Korea Food and Drug Administration on Tuesday granted approval to the country's first drug to treat impotence.

The watchdog said it confirmed Dong-a Pharmaceutical's Zydena as safe and effective through clinical tests on 650 patients at 13 medical institutes, and that the United States is also testing the product.

Dong-a said it spent eight years and 20 billion won to develop the drug, the fourth of its kind in the world after Viagra, Levitra and Cialis.