Merck & Co., Inc. (NYSE:MRK ) probably thought that long-dormant legal claims about previously undisclosed risks associated with its osteoporosis drug Fosamax were dead and buried but those decades-old claims have been revived again by a major court decision on Wednesday.

Written by StockNews.com

A federal appeals court has brought back hundreds of claims against the drug giant by plaintiffs who accused the company of failing to adequately warn them about the risks of femur fractures in patients taking Fosamax. Reuters has some more color on the ruling:

In a 3-0 decision, the 3rd U.S. Circuit Court of Appeals in Philadelphia said the plaintiffs may proceed to trial on their failure-to-warn claims, and a lower court judge erred in finding the claims pre-empted by federal law.

Fosamax has been in use since 1995, but Merck didn’t add a thigh bone fracture risk warning label to it until 2011. Patients have long since claimed the company knew about the risks for years and covered the issue up until it was forced to admit femur break risks later down the road.

Back in 2014, U.S. District Judge Joel Pisano in Trenton, New Jersey dismissed all claims against Merck prior to a USDA task force report published on Sept. 14, 2010. That left only about 20 people’s claims in tact but today’s ruling brings back the pre-2011 claims, potentially opening up Merck for hundreds of millions in damages.

Fosamax was a blockbuster drug for Merck, seeing annual sales over $3 billion prior to losing patent exclusivity in 2008. Since then, it’s been available as a generic drug, although its brand name "variat" still generated $284 million in sales in 2016.

...Year-to-date, MRK has gained 8.51%, versus a 4.66% rise in the benchmark S&P 500 index during the same period.

MRK currently has a StockNews.com POWR Rating of A (Strong Buy), and is ranked #3 of 134 stocks in the Medical – Pharmaceuticals category.