Drugmaker Mylan has started selling a generic version of its emergency allergy treatment EpiPen at half the price of the branded option, the cost of which drew national scorn and attracted Congressional inquiries.

The launch of Mylan's long-promised generic alternative is expected to still generate millions of dollars in revenue for the drugmaker while also protecting its market share against current and future competition.

Mylan NV said Friday that it will charge $300 for the generic version of its life-saving injections, which come in a two pack. The generic version will reach retail pharmacies starting next week.

The list price of an EpiPen two-pack, which is stocked by schools and parents of children with severe allergies, has grown to $608, an increase of more than 500 percent since 2007.

Earlier this year, a Congressional panel grilled Mylan CEO Healthier Bresch about the soaring cost, which she has blamed in part on an outdated and complex system for pricing drugs.