Growing Body of Studies
Consumers are likely confused by this latest news in the battle over the safety of bone-building drugs.
A new study offers reassurance for the millions of Americans who take bisphosphonates, that help build bone debilitated by osteoporosis.
It was released the same month another study indicated that post-menopausal women who take bisphosphonates suffer from an unusual type of femur fracture near the hip.
An estimated 10 million Americans, mostly women, have osteoporosis.
Bisphosphonates include Actonel, Boniva, Fosamax and Reclast.
Folsamax and Reclast use do not increase the risk of a rare type of leg fracture, reports Dr. Dennis Black of the University of California, San Francisco.
The Latest Study
The results were published in the New England Journal of Medicine in its online edition Wednesday.
In this study of more than 14,000 women, researchers looked for the rare hip or femur fractures. They found 12 of the unusual fractures in 10 patients, mostly bisphosphonate users, and 284 hip and leg fractures. Participants received a placebo, Fosamax, or Reclast.
The fractures of the subtrochanteric or diaphyseal femur are very rare, even when a woman takes bisphosphonates for a decade, researchers conclude. The drugs provide more benefit than harm, says Dr. Black.
“If we treated 1,000 osteoporatic women for three years, we estimate you would prevent 100 fractures” he said. At the same time there may be one of the unusual bone breaks.
Bisphosphonates include Actonel (Warner Chilcott), Reclast (Novartis), Fosamax (Merck), and Boniva (GSK). The drugs work by slowing or stopping the breakdown and reabsorption of bone, a lifelong process.
Even Dr. Black reports there are too few of the unusual fractures for definitive proof.
After the critical studies about the unusual femur fracture appeared earlier this month, the FDA posted on its Website a notice that it will look into the safety issue.
The two separate critical studies suggested that long-term use of bisphosphonates that slow or stop bone loss during the natural remodelling cycle, may alter the properties of bone, making them less structurally sound and more brittle and prone to breaking.
Users may be substituting bone quantity for bone quality after prolonged use.
Just what constitutes prolonged use may be the critical factor.
In an editorial in the NEJM, researcher Dr. Elizabeth Shane of Columbia University writes that some in the UCSF study took the bone-building drugs for only three years, and some took a low dose of Fosamax.
The problems with unusual femur brakes were seen in patients using the drugs for five or more years. Dr. Shane also believes that bisphosphonates may prevent far more common hip fractures than they cause rare ones.
Dr. Black reports to the NEJM that he is receiving grants (to UCSF) from Merck, Novartis, Amgen, and Roche and travel reimbursements from Merck and Novartis, who also supported the research. The study was sponsored by Merck and Novartis. Several other authors work for the companies, while others consult and receive compensation for their work from the makers of bisphosphonates.
Dr. Shane is with the American Society for Bone and Mineral Research that is evaluating the risk of these unusual fractures. Columbia University receives research grants from drug makers. She says she has no personal financial ties to any, reports AP.
At $3.5 in annual sales, the bone-building business is a lucrative one and Pfizer (Fablyn) and Amgen (Denosumab) have bone-building drugs in the FDA pipeline. They suffered a setback in approval as a result of the controversy.
This isn’t the first bad news for the bone-building drugs.
Bisphosphonates have previously been linked to an inability of jaw bone to regrow after oral surgery also known as osteonecrosis of the jaw, and serious, life-threatening atrial fibrillation, an irregularly fast heartbeat
In 2008, researchers at the University of Washington found that Fosamax use was linked to a woman’s risk of developing atrial fibrillation, (AF) a chronic irregular heart beat that can cause dizziness and fainting as well as fatigue and in rare cases it can lead to a blood clots and stroke. #