Heartbeat risk for thousands taking osteoporosis drug
Last updated at 00:25 29 April 2008
Fosamax is used to treat bone thinning after the menopause
Thousands of British women take Fosamax, also known as alendronate, to treat bone-thinning after the menopause.
But U.S. researchers have found a link between the drug and atrial fibrillation, a rhythm disorder which causes the heart to beat erratically.
Although atrial fibrillation is not fatal in itself, it can cause the blood to pool and form potentially dangerous clots.
Fosamax is one of a class of drugs called bisphosphonates which slow the rate at which bone disintegrates.
In the latest study, researchers from the University of Washington in Seattle studied 719 women diagnosed with atrial fibrillation.
They were compared with 966 randomly chosen women who did not have the condition, says a report in the journal Archives of Internal Medicine.
More than 6 per cent of the atrial fibrillation patients had taken the osteoporosis drug against just over 4 per cent of the second group.
Lead researcher Professor Susan Heckbert said: "Having ever used alendronate was associated with an 86 per cent higher risk of newly detected atrial fibrillation compared with never having used the drug."
Professor Heckbert, who is based at Group Health, a non-profit organisation providing health care in Seattle, said the benefits of taking Fosamax would outweigh the risk for most women likely to suffer bone fractures.
In Britain, around 70,000 hip fractures are caused by osteoporosis each year and 14,000 patients die as a result.
Professor Heckbert said: "Careful judgment is required to weigh the risks and benefits of any medication for any individual patient.
"Women who are at high risk of fractures but also have risk factors for atrial fibrillation - such as heart failure, diabetes, or coronary disease - might want to discuss alternatives to alendronate with their health care providers."
Evidence shows hormone replacement therapy can also prevent fractures by replacing oestrogen after the menopause, but it is not recommended for osteoporosis.
It is unclear why Fosamax, which is made by Merck & Co, might increase the chances of atrial fibrillation, but bisphosphonates may disrupt regulatory proteins, trigger inflammation and cause small decreases in blood calcium and phosphate levels.
Any of these effects could cause changes in the heart chambers known as the atria and alter heartbeat, say researchers.
Women taking HRT after the menopause have a slightly higher risk of stroke, according to researchers at Brigham and Women's Hospital and Harvard Medical School, Boston.
They found an extra risk of 39 per cent for women on oestrogen-only HRT in a study of 121,700 women taking part in a study from 1976 to 2004.
There were 360 cases of stroke among women who had never used hormones and 414 strokes in women taking hormones.
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