Another study, this time out of Sweden, has found a link between bisphosphonates, such as Fosamax, and a rare type of thigh fracture in women. However, the study also found that the atypical thigh fractures were a rare event, and that risk was impacted by the length of time women took bisphosphonates.
Bisphosponates, which in addition to Fosamax, include drugs sold under brand names like Actonel, Zometa and Boniva, are used to treat osteoporosis in post-menopausal women. According to The Wall Street Journal, the drugs are very popular, with 36.5 million prescriptions dispensed for the drugs in 2010. Total U.S. sales for bisphosphonates were $4.2 billion the same year.
The study, which was published in The New England Journal of Medicine, drew data from a Swedish database that included all 1.5 million women in that country over 55. They evaluated x-rays of 1,243 women who had experienced thigh fractures. Of those, 59 turned out to have suffered the rare type of thigh fracture, where the bone breaks in two. Those 59 subjects were compared with 263 controls with fractures in a similar location. The study found that 78 percent of the women with atypical fractures took bisphosphonates, compared with 10 percent of controls.
The researchers also found that when women stopped taking bisphosphonates, their fracture risk dropped by 70 percent.
The Swedish study validates last year’s decision by the U.S. Food & Drug Administration (FDA) to require the makers of bisphosphonates to add information to the “Warnings and Precautions” section of the drugs labels’ describing the risk of atypical thigh fractures. The FDA’s action was prompted by another study of that found that out of 300 cases women who had suffered atypical thigh fractures, 94 percent had taken bisphosphonates for osteoporosis. Most of the subjects in that study had been taking the drugs for five years or more.