The U.S. Supreme Court has thrown out a lower court's ruling against Merck & Co. Inc. that revived hundreds of lawsuits accusing the pharmaceutical giant of failing to warn patients about the risks of thigh bone fractures linked to its osteoporosis medicine Fosamax, Reuters reported.

At issue in the case is whether Merck should be held responsible for failing to warn patients about the risks associated with Fosamax under state law, when the company had appealed to the U.S. Food and Drug Administration in 2008 to add a warning to the drug's label. The U.S. drug regulator denied the request. The plaintiffs in the case argue that the request was rejected because it did not fully explain the scope of the risk, Reuters reported.

The Supreme Court justices unanimously ordered the 3rd U.S. Circuit Court of Appeals to reconsider allowing lawsuits against the Kenilworth, N.J.-based company to go ahead. The lower court had previously found that the lawsuits could proceed because the FDA had rejected Merck's request due only to the phrasing of the warning.

Drugmakers often defend against product liability by arguing that litigation in these matters is "pre-empted" by federal law when a federal agency, such as the FDA, takes certain actions, Reuters said. The Supreme Court found that judges, not juries, are responsible for determining "pre-emption."

Several hundred plaintiffs have alleged that they suffered fractures after using the osteoporosis drug for an extended period. They also claimed that the company had knowledge of the side effects for more than 10 years before a warning was added to the drug's label in 2011. The company made the change to the label after a task force appointed by the FDA linked the drug to the fractures in a report published Sept. 14, 2010.

Fosamax is used to prevent osteoporosis — a condition that weakens the bones making them prone to fracture — in postmenopausal women and as a treatment to increase bone mass in men with osteoporosis. The medicine generated sales of $209 million for the full year 2018.