The U.S. Food and Drug Administration (FDA) is facing a lawsuit filed by two health advocacy groups that requested the clinical trial data of Gilead's breakthrough hepatitis C drugs Sovaldi and Harvoni. The complainants said that the federal agency failed to disclose the data on a timely basis.

Last year, the FDA approved Gilead's hepatitis C drugs through a regulatory process known as a breakthrough therapy designation. This process was introduced in 2012 where the agency can expedite the review and approval of a drug if it could treat serious, life-threatening conditions and its preliminary clinical trial results can significantly benefit the consumers. A drug can be approved or denied within 60 days.

The FDA approved Sovaldi in September last year, then Harvoni the following month. The drugs became controversial because of their hefty price tags. Solvaldi was estimated to cost at least $84,000 for a 12-week treatment while its follow-up medication Harvoni costs $94,500 for the same treatment period. Many were disappointed, including the lawmakers, that the FDA approved these pricing saying that the prices are fair enough as they can extend survival.

Because the drugs were so hyped and their prices are soaring high, it isn't surprising that some health advocacy groups will question the efficacy and pricing of the treatments. Treatment Action Group and the Global Health Justice Partnership asked Gilead for the clinical data last year but they didn't receive a response. They turned to the FDA and was informed that they would need to wait for 18 to 24 months, despite the groups' request for expedited processing.

“This delay will leave doctors and patients in the dark for too long,” Amy Kapczynski, a Yale Law School professor who heads GHJP, told the Wall Street Journal. “Doctors write thousands of prescriptions for these drugs every week, straining budgets of state health care programs."

The health groups argued that the clinical data would allow doctors and policymakers revisit the costs of the drugs and determine possible health consequences related to the drugs.

Both Gilead and the FDA refused to comment on the lawsuit.