A trio of House Republicans is demanding to know what the Food and Drug Administration is doing to approve new versions of the life-saving allergy drug EpiPen to compete with a high-priced version.

Leaders of the House Energy and Commerce Committee wrote to the FDA on Monday for answers on the lack of generic competition for EpiPen, for which drugmaker Mylan now charges $600 for a two-pack.

"Improving the generic drug review process will promote competition and ultimately lower the cost of prescription drugs for America's patients," according to the letter signed by Committee Chairman Rep. Fred Upton, R-Mich., and Pennsylvania Republicans Tim Murphy and Joseph Pitts.

The lawmakers ask how many new applications that compete with Mylan's EpiPen have been submitted and are pending. They also asked when the applications were submitted.

In addition, the letter asks if the FDA prioritized the review of an EpiPen alternative. The agency does not prioritize applications due to economic issues such as fostering more competition.

The letter also referred to a steep backlog of thousands of generic drug applications that the FDA is tasked with addressing. The agency agreed to tackle the backlog as a goal of a user fee program in which generic drugmakers pay the agency whenever they submit a new application.

The user fee agreement, with others for brand-name drugs and devices, is up for re-authorization by Congress next year. Lawmakers have divided along partisan lines in some cases when responding to high drug prices, with Republicans quick to criticize the FDA for not approving enough new products and Democrats lashing out at the companies for setting such high prices.

Mylan has tried to quell the outcry by releasing a cheaper version of the EpiPen in the next few weeks.

However, an earlier effort to provide a $300 discount through a discount card fell on deaf ears. Lawmakers criticized the discount as a crass PR move that doesn't actually lower the price of the EpiPen.

Mylan is still not lowering the price of the EpiPen, just creating a new version that is $300 cheaper.