Sildenafil is the generic form of the brand-name medication Viagra. Sildenafil is a certain type of enzyme inhibitor used to treat erectile dysfunction (ED).

Founded in 2002, Amneal Pharmaceuticals distributes more than 225 drugs in the U.S. In 2011, it was the seventh largest generics company in the country. Amneal has 14 manufacturing sites including in the U.S., India, and Ireland