TORONTO — Nitroglycerin is often prescribed for patients with a heart condition, but it’s being looked at now as a possible treatment for osteoporosis.
Nitroglycerin ointment applied at bedtime by postmenopausal women modestly increased bone mineral density and decreased bone loss, according to results of a preliminary Canadian study published Tuesday in the Journal of the American Medical Association.
“It’s very promising. It’s very exciting, but I think the next study needs to be a larger study to confirm what we found, and then a second study to look at the effects of nitroglycerin on fracture risk reduction,” said Dr. Sophie Jamal of the Women’s College Research Institute and University of Toronto.
The two-year study involved 243 women with an average age of about 64. They were randomized to either apply 15 milligrams of nitroglycerin ointment to their upper arm at bedtime or a placebo. The women in the study did not have the bone-loss disease osteoporosis.
Jamal said the nitroglycerin was absorbed through the skin, and the ointment was wiped off in the morning.
“What we found is that women who were taking the nitroglycerin ointment had much higher bone density by about 67 per cent at the hip and spine, compared to women who were taking placebo,” Jamal said in an interview.
“They also had an improvement in bone geometry and bone structure, and they also had an increase in the bone formation, and a decrease in the bone breakdown.”
She said nitroglycerin has the potential to have a huge impact on fracture reduction, but the study was too small to measure this.
As for how and why it works, she explained that nitric oxide is ubiquitous in the body — bone cells actually make nitric oxide.
“There’s been some cellular data that nitric oxide is needed for bone cells to build bone, and if you don’t have a lot of nitroglycerin, the bone cells that break down bones tend to overact.
“And one of the hypotheses is that when women go through menopause and they have less estrogen, they also have less nitric oxide.”
A downside to the nitroglycerin treatment was the incidence of headaches among many patients using it — a side-effect that’s also been experienced in patients using nitroglycerin for angina.
A run-in phase before the study got underway weeded out those who couldn’t tolerate nitroglycerin because of headaches. Among those who got headaches but stuck with the study, Jamal said the headaches were more frequent in the first month or two, “and then after that people really got used to it.”