Feb. 22, 2011 -- Women at risk of fractures who used the heart medicine nitroglycerin boosted their bone density modestly, according to a new study.
''We found nitroglycerin has a unique ability," says researcher Sophie Jamal, MD, PhD, associate professor of medicine at the University of Toronto. "What it does is both increase bone formation and decrease bone breakdown."
No osteoporosis drug does both to her knowledge, Jamal tells WebMD.
Her study, reported in the Journal of the American Medical Association, did not assess fracture risk with nitroglycerin use, only the effects on bone. She plans to look next at whether taking nitroglycerin for bones will reduce fractures.
While several medicines are on the market to treat osteoporosis, the brittle bone disease that can lead to fractures, Jamal says many are expensive and not all drugs are available worldwide. In the U.S., up to one of every two women and one of four men over age 50 is expected to have an osteoporosis-related fracture at some point, according to the National Institutes of Health.
When used for heart conditions, nitroglycerin causes constricted blood vessels to dilate, relieving the severe chest pains known as angina.
Previous research by others has found that women taking nitroglycerin for heart problems had a lower risk of fractures, and other studies found its use is associated with a reduced fracture risk.
Jamal and colleagues assigned 243 women, average age about 62, to either a nitroglycerin ointment group or a placebo ointment group. The women applied either the nitroglycerin (15 milligrams) or placebo to their upper arm at bedtime, squeezing out about an inch of the medicine.
The researchers, who conducted the study from November 2005 to March 2010, did not accept women who already had osteoporosis or any medical condition that affected bone metabolism.
Bone density was evaluated at the study start and again at the 12-month and 24-month mark.
At the end, they found the women in the nitroglycerin group, compared to those in the placebo group, had a:
6.7% increase in bone mineral density at the lumbar spine
6.2% increase in bone mineral density at the hip
7% increase in the thigh bone density
The group taking the nitroglycerin also had an increase in a marker of bone formation and a decrease in a marker for bone loss.
Headache was the most common side effect reported by those in the nitroglycerin group, with 35% of participants complaining of it compared to 5.4% in the placebo group in the first month. Over time, the headaches in the treated women declined.
The study was funded by the Canadian Institute of Health Research and the Physicians' Services Incorporated.
Jamal has received support for board membership from Novartis, Amgen, and Warner-Chilcott and has been a consultant for Genzyme, Warner-Chilcott, Novartis, and Shire.