FDA to review osteoporosis drug safety

The US Food and Drug Administration (FDA) is to review the safety of long-term use of certain osteoporosis drugs after they were linked to atypical fractures in the femur.

The medicines, known as bisphosphonates, are currently used to enhance bone density and reduce fracture incidence in post-menopausal women. This may, however, adversely affect bone quality when used for four or more years according to two separate pieces of research delivered to at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS).

These studies, one from Hospital for Special Surgery (HSS) and the other from Columbia University Medical Center, suggested that bisphosphonates, designed to slow or stop the bone loss that occurs during the body's bone remodelling cycle, could alter the material properties of bone if taken over a long-term period. This has the potential to weaken the bone's integrity and increase the risk of atypical fractures.

"In the early treatment period, patients using bisphosphonates experienced improvements in all parameters, including decreased buckling ratio and increased cross-sectional area," said Dr Melvin Rosenwasser, orthopaedic surgeon for Columbia University Medical Center, whose study evaluated the bone structure of 111 postmenopausal women with primary osteoporosis, 61 of whom had been taking bisphosphonates for a minimum of four years and 50 controls taking calcium and vitamin D supplements

"However, after four years of use," he continued "these trends reversed, revealing an association between prolonged therapy and declining cortical bone structural integrity."

The HSS study found similar changes in the material properties of bone in bisphosphonate-treated patients in an analysis of the bone composition of 21 post-menopausal women who were treated for femoral fractures, of which 12 had a history of the treatment.

Both sets of researchers added that the true efficacy of long-term clinical use of bisphosphonates was uncertain, and more research was necessary.

"Bisphosphonate use still is a very effective solution that prevents bone loss in most patients and no one is recommending that physicians avoid prescribing these," said Dr Rosenwasser. "However, as baby boomers age and continue to remain active, it is important that we conduct more research and develop sustainable, safe and effective treatments for osteoporosis."

The FDA has said that, although current analysis of data has "not shown a clear connection between bisphosphonate use and a risk of atypical subtrochanteric femur fractures" the agency is "working closely with outside experts, including members of the recently convened American Society of Bone and Mineral Research Subtrochanteric Femoral Fracture Task Force, to gather additional information that may provide more insight into this issue."

They have also offered guidance for healthcare professionals and patients on the use of bisphosphonates, for which common brand names include Fosamax (Merck), Actonel (sanofi-aventis), Boniva (Genentech/Roche), and Reclast (Novartis).

These guidelines include suggestions to health professionals to discuss with patients the known benefits and potential risks with using oral bisphosphonates, as well as to continue following the recommendations on the drug label when prescribing the medicines. Patients are recommended to not stop taking their medication unless told to do so by their healthcare professional.