February 22nd, 2011
05:27 PM ET
Osteoporosis, a condition where the bones become weak, affects 10 million people in the U.S. Two studies released Tuesday in the Journal of the American Medical Association looked at osteoporosis prevention and treatment. One found a nitroglycerin ointment may someday be an inexpensive, widely available means of prevention. The other found a small increase in the risk of atypical fractures associated with the long-term use of the class of drugs known as bisphosphonates.
The nitroglycerin ointment, applied to one part of the skin, was shown to have effects all over the body.
"It differs from current drugs, which either inhibit the breakdown of bone or stimulate the formation of new bone," said Dr. Sundeep Khosla of the Mayo Clinic, who wrote an accompanying editorial. "Nitroglycerin tends to do a little bit of both, which would put it in a unique class by itself."
Researchers at the Women's College Research Institute and University of Toronto, Canada, studied 243 women for two years. They were postmenopausal and aged 50 or older. They applied either a placebo or the ointment once daily.
At the end of the study, researchers found its use was associated with a modest rise in density and a decrease in bone loss.
But Khosla says he wouldn't recommend people rush out to buy nitroglycerin ointment, a current treatment for some heart conditions.
"About a quarter of the people (in the study) developed significant headaches," he said.
"It offers a new direction for drug development," he added. "Maybe the pharmaceutical industry will become interested in this and start developing other compounds that work like nitroglycerin does, but maybe doesn't have the side effect of headache and so forth. Those are questions for the future."
The second study looked at long-term use of bisphosphonates, a class of drugs used commonly to treat osteoporosis. They're sold under such brand names as Fosamax, Actonel, Boniva and Reclast.
The researchers looked at the records of all women in Ontario who were age 68 or older with a thigh bone fracture and compared them with women who didn't have those fractures. They also studied the length of time that the women of these two groups had been on the oral bisphosphonate drugs.
"We found a small increase in the risk of thigh bone fractures in women who took these drugs for five years or more," said study author Laura Y. Park-Wyllie of St. Michael's Hospital in Toronto, Ontario. "The risk-benefit for women who have osteoporosis and are at high-risk of fractures favors continuing treatment because, on average, the benefit will outweigh the risk."
For women taking the drugs less than five years, researchers did not see an increase.
In October 2010, the Food and Drug Administration said it's continuing its safety review on the drugs. The atypical fractures involved the femoral shaft (bone in the leg extending from the hip to the knee) or subtrochanteric (fractures in the bone just below the hip joint.)
Park-Wyllie said that a typical hip fracture normally seen with osteoporosis would occur in the upper part of the thigh bone, or femur, which is close to the hip joint.
"Long-term use of the drugs may warrant reconsideration, especially for patients who are at relatively low risk of fracture," she added. "So women taking these drugs, who are not considered to be at high risk for fracture [from osteoporosis], can talk to their doctors about whether they should continue or stop taking the drug."
Park-Wyllie noted that a doctor can assess risk by looking at a patient's history of fracture, age, whether she is postmenopausal, family history, medical conditions and medications. The research noted that bisphosphonate use was effective in reducing the risk of typical osteoporosis fractures.
"Why these thigh bone fractures could be occurring, there isn't a good understanding of, or how they're occurring," Park-Wyllie said. "It's an important question that future research should direct their efforts at."
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