A high-priced drug approved last week to treat a rare disease that affects young boys is not hitting the market after criticism over its $89,000-a-year price tag.

Marathon Pharmaceuticals said Monday that it is delaying the launch of Emflaza, a drug to treat the rare muscular disorder Duchenne muscular dystrophy. The Illinois drugmaker didn't say how long the drug would be delayed or when it initially planned to hit the market.

The company's CEO, Jeff Aronin, said in a letter that it is pausing the launch to meet with drug advocates and "explain our commercialization plans, review their concerns, discuss all options, and move forward with commercialization."

The delay announced Monday comes the same day that Sen. Bernie Sanders, I-Vt., and Rep. Elijah Cummings, D-Md., demanded answers about the $89,000 annual price for Emflaza.

The drug is a steroid that has been marketed overseas for $1,000. The Food and Drug Administration approved the drug to treat Duchenne's muscular dystrophy last week.