Prolia Femur Fracture Warning Issued to Doctors in Canada

A warning has been provided by Canadian health officials about the potential risk of sudden femur fractures associated with side effects of Prolia, an osteoporosis drug sold by Amgen. However, it does not appear that similar warnings have been provided to doctors in the United States.

Health Canada and Amgen Canada, Inc. issued a warning letter (PDF) last month, informing health care providers in Canada that some users of Prolia have suffered atypical femur fractures, which can occur with little or no trauma to the thigh bone.

The sudden fractures appear to be similar to those associated with the side effects of Fosamax and other bone-strengthening drugs that are part of a class of medications known as bisphosphonates. However, Prolia does not belong to that family of drugs.

Health Canada and Amgen warn that if a patient using Prolia experiences any new pain in the thigh, hip, or pelvic area, they should contact their health care provider immediately. The label for Prolia has been updated to include the new warning information.

According to Amgen, Prolia femoral fractures have been confirmed among patients who are part of an ongoing study to extend the use of of the drug for postmenopausal osteoporosis.

The fractures appear to occur in one out of every 10,000 patients that use the drug. In most cases the fractures produce a dull, unusual aching pain in the thigh, hip, or pelvis area.

While Prolia is sold in both the United States and Europe, there have been no similar warnings by the FDA or the European Medicines Agency (EMA). However, there have been warnings for other bone drugs.

Merck & Co. currently faces hundreds of Fosamax femur fracture lawsuits that have been filed by individuals who claim the drug maker failed to adequately warn about the potential risk of problems.  Complaints allege that side effects of Fosamax may weaken the ability of the femur bone to repair itself from microdamage, increasing the risk of a sudden femur fracture.

In October 2010, the FDA required the Merck and the manufacturers of other bisphosphonate medications approved for treatment of osteoporosis to add warnings about the risk of sudden femur fractures. Since then, information has been provided in a Medication Guide distributed with each prescription for the drugs, warning consumers to contact their doctor if they experience new thigh or groin pain, which can occur weeks or months before a complete femur fracture occurs on the osteoporosis drugs.