A popular group of drugs used to slow bone loss may be putting some patients at an increased risk of hip fractures if taken for more than five years.
Two studies reported at this week's conference of American Academy of Orthopedic Surgeons show the bones of some postmenopausal women who take bisphosphonates (Actonel, Boniva, Fosamax, Reclast) to ward off osteoporosis can stop rejuvenating and become brittle.
The Food and Drug Administration (FDA) is reviewing long-term bisphosphonate use but hasn't seen the studies, spokeswoman Elaine Bobo says.
"These drugs are good drugs," says Melvin Rosenwasser, chief of orthopedic trauma surgery at Columbia University Medical Center in New York. "They strengthen bone and protect you from fractures for a while. But in some people, they can become deleterious after a period of time."
Osteoporosis is a threat for the aging population, especially women. An estimated 10 million Americans have it, and 34 million have low bone mass, which puts them at risk for spine, hip and wrist fractures. Bisphosphonates are among the nation's top sellers; annual sales exceed $3.5 billion.
The drugs are effective initially in slowing bone loss, says Joseph Lane, chief of metabolic bone disease service at the Hospital for Special Surgery in New York. In research he will present today, he studied bone biopsies of women who had atypical hip fractures of the femur and found the quality of the bone diminished after long-term bisphosphonate use. "Normally, bone is a distribution of young bone, middle-age bone and old bone," he says. "When we look at these bones, it's old bone."
In Rosenwasser's research, also presented this week, bone densitometry scans show buckling potential in the hip's femur area in patients who have taken the drugs for four years or more.
Ron Rogers of Merck says that "causal association has not been established" between Fosamax and the femur fractures and that the fractures also have occurred in non-bisphosphonate cases. Merck is funding studies "to further investigate this issue."
Terry Hurley of Genentech says Boniva's "safety and efficacy" have been proven in clinical trials, and the company "will work closely with the FDA to better understand the reports of these fractures."
Lane suggests patients talk to their doctors if they have been on the drugs for more than five years, and he recommends routine bone scans.
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