US FDA adds 'boxed warning' for Amgen's bone loss drug Prolia

Jan 19 (Reuters) - The U.S. Food and Drug Administration added a serious warning on the prescribing information for Amgen's (AMGN.O), drug Prolia to treat bone loss as it increases the risk of severely low calcium levels in certain patients.

The so-called boxed warning, issued on Friday, comes after the health regulator in 2022 started a review into the risk of very low blood calcium in patients with advanced chronic kidney disease, particularly ones on dialysis, and Prolia.

The FDA reviewed 25 cases between July 2010 through May 2021 during the investigation.

Boxed warnings are the strictest warnings issued by the FDA regarding the potential serious side effect from the use of a drug.

Prolia, approved in 2010 to treat bone loss in postmenopausal women and later approved to treat men and women at high risk of fracture, brought in total third-quarter sales of $986 million.

The drug is set to lose its U.S. patent in February next year.

Several other drugs, which treat bone loss or osteoporosis, including Merck's (MRK.N), Fosamax, Amgen's Xgeva and Evenity, already come with safety information that warn against prescribing the drug to patients with kidney disease.

Kidney disease causes low levels of calcium, and the drugs could lead to death or severe injury in those patients.

Amgen's shares were marginally lower on Friday.