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More Bad News About Fosamax

An unusual type of severe fracture has been reported in people taking Fosamax for more than five years. Ironically, this drug is widely prescribed to prevent fractures in people with bone loss. The new finding came from a series of case reports published in the May/June Journal of Orthopaedic Trauma.

The fractures occurred in the femur, which is the large thighbone that connects to the hip. They are particularly alarming because of the unusual pattern described by many of the people whose cases were reported. Their thighbones had ached inexplicably for months or weeks and then broke spontaneously while walking or standing. Nineteen of the 20 people in the case series had been taking Fosamax for an average of nearly seven years.

These are not the first reports of what is called atypical low-energy fractures after long-term Fosamax (generic name: alendronate) therapy. In 2005, the Journal of Clinical Endocrinology & Metabolism published case reports of nine women who sustained spontaneous non-spinal fractures while on Fosamax, six of whom showed either delayed healing or no healing for three months to two years. And last year, the Journal of Bone and Joint Surgery reported that nine Fosamax-treated women in Singapore showed the same early warning signs prior to a spontaneous fracture.

These adverse effects are not unexpected. Ever since Fosamax first came on the market over a decade ago, some osteoporosis researchers have periodically expressed safety concerns about prolonged usage, mostly in letters to medical journals. The drug improves bone density, but it does so by suppressing the bone remodeling process by which microscopic parts of old bone are constantly being dissolved and new bone is added.

Here’s how bone physiologist Susan Ott, MD, describes Fosamax’s effect on this process, “The bisphosphonates get deposited in the bone and will accumulate for years. It is possible that many years of continuous medicine would make bone more brittle or impair the ability to repair damage. Bisphosphonates do reduce fractures and improve measurements of bone strength for the first five years in both animal studies and in women who have osteoporosis. After five years, the fracture rates are as high in the women who keep taking alendronate as in the women who quit (see http://courses.washington.edu/bonephys).”

Although Fosamax advertising has focused women and doctors on the importance of bone density, bone strength is now regarded by osteoporosis researchers as more important to fracture prevention (see HealthFacts, April 2008).

Atypical low-energy fractures did not appear in the clinical trials required of Merck, maker of Fosamax, for FDA approval because these trials lasted only three to five years. Although these fractures are considered to be a rare side effect at this time, some osteoporosis experts are now advising against taking the drug beyond five years.

The published case reports all involved Fosamax, which is one of a drug class called bisphosphonates. Others in the class include: Actonel, Boniva, Aredia and Didronel. That all the case reports are confined to Fosamax may be explained by the fact that Fosamax was the first bisphosphonate to be aggressively marketed for the treatment of osteoporosis, and many more women worldwide have been taking this particular bone drug and for a longer time.
It’s reasonable to assume that the spontaneous fracture risk is associated with prolonged use of any bisphosphonate until research proves otherwise.