Femoral Stress Fractures Are Possible Fosamax Side Effect
Dueling Studies Show Fosamax Might Cause Atypical Fractures of the Femur and It Might Not
UPDATE: The FDA may require Merck to make a Fosamax label change to increase their warning about atypical femur fractures after a task force appointed by the American Society for Bone and Mineral Research (ASBMR) issued its report in September 2010, which included such a recommendation.
UPDATE: New research about femur fractures after long-term Fosamax use is presented in March 2010 at national medical meeting on same day FDA Drug Safety Communication about Fosamax states current evidence does not show any link between bisphosphonates and leg bone side effects.
In a June 26, 2008 press release, "Some Patients Using Fosamax Over the Long-Term May Be at Risk for One Type of Fracture", issued by NewYork-Presbyterian/Weill Cornell Medical Center, the study results were summarized:
The preliminary study followed 70 patients, 25 of whom were taking alendronate (Fosamax) for an average of five years. Among those receiving the therapy, 19 patients (76 percent) presented with one type of femoral stress fracture (simple, transverse) that resulted from little or no trauma. By comparison, the fracture type was only evident in one patient (2 percent) not receiving the therapy.
This Fosamax study and its findings are reported by Drs. Dean G. Lorich and Joseph M. Lane of NewYork-Presbyterian Hospital/Weill Cornell Medical Center in the latest issue of the Journal of Orthopaedic Trauma.
Dr. Lorich, the study's senior author, says, "While bisphosphonates like Fosamax have been proven to successfully treat osteoporosis and other metabolic bone disease, we believe long-term use of these drugs may suppress the ability of bones to heal in some patients. As a consequence, patients with routine stress fractures are unable to properly heal, and minor damage can worsen until a serious fracture occurs.
Dr. Lane, the study's corresponding author cautions that although further research is necessary, physicians prescribing bisphosphonates for longer durations should monitor patients for indications of bone regeneration. In situations where a blood test reveals low bone turnover, a holiday from the bisphosphonates would be recommended until these markers return to an acceptable level.
More recently, in September 2008 at the American Society for Bone and Mineral Research (ASBMR) meeting in Montreal, Bo Abrahamsen, Ph.D., of Copenhagen University Hospital Gentofte, asserted that patients treated with the anti-osteoporosis drug Fosamax apparently had a higher risk of these atypical fractures (as well as fractures of any kind) to start with for the simple reason that they were taking a drug known to reduce the risk of hip fractures.
In a September 15, 2008 Medpage Today article, "ASBMR: Alendronate Exonerated in 'Atypical' Femoral Fractures" due to Fosamax use, "The three case reports earlier this year suggested that a common factor in patients with subtrochanteric or proximal diaphyseal fractures of the femur is [Fosamax] use," Dr. Abrahamsen said.
He went on to say that the reports not have any comparison data and that the real problem is the denominator and knowing how common it is. Dr. Abrahamsen insists it's important to know how common such fractures are in comparison with hip fractures in order to understand the risks and benefits of the treatment.
To help fill the gap, he and colleagues looked at registry data for all patients born 1945 or earlier who arrived at Danish hospitals with fractures from 1996 through 2005.
The conclusion was that the atypical fractures are best classified as osteoporotic fractures and that there is no evidence that Fosamax increases the risk of the atypical broken bones.
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