WEDNESDAY, Aug. 13, 2008 (HealthDay News) -- Women 60 and older taking the hormone-replacement therapy drug tibolone to relieve menopausal symptoms are at an increased risk for stroke, a new study finds.
Tibolone is a synthetic drug that acts like the female hormones estrogen and progesterone in relieving menopausal symptoms. But, unlike estrogen and progesterone, it also reduces the risk of some cancers, the study authors said.
"Tibolone, which is used around the world for menopausal symptoms, decreases the risk of fractures, decreases the risk of breast cancer, but increases the risk of stroke in this group of women who are all over the age of 60," said lead researcher Dr. Steven R. Cummings, of the California Pacific Medical Center Research Institute in San Francisco.
The drug shouldn't be used in women over the age of 60, particularly those with an increased risk for stroke, Cummings said. "For older women, you should stop taking tibolone or not consider starting it," he said, adding that the drug is not available in the United States.
Earlier studies have shown that hormone replacement therapy (HRT) with estrogen increases the risk for stroke, no matter at what age women start using it. Many physicians recommend that only women with the most severe menopausal symptoms use any form of HRT.
For the new study, published in the Aug. 14 issue of the New England Journal of Medicine, Cummings's team randomly assigned 4,538 postmenopausal women to daily 1.25 milligram doses of tibolone or a placebo. Over the 34 months of the study, the researchers looked for spine fractures among the women and the rates of cardiovascular problems and breast cancer.
The researchers found fewer cases of spine fractures among women taking tibolone compared with women receiving a placebo -- 70 cases versus 126 cases per 1,000 person years, respectively. And, women taking tibolone were at a reduced risk of breast cancer and colon cancer.
But, women taking tibolone had a 2.2 times increased risk of stroke. This increased stroke risk caused the study to be stopped in February 2006, before the trial was complete.
For younger women, tibolone may be a good choice for relieving menopausal symptoms, Cummings said.
"Women who are having menopausal symptoms in their 50s can continue to take tibolone, because it is relatively safe and also does have other benefits, such as a reduction in the risk of fracture and breast cancer," he said.
Cummings noted that tibolone is not available in the United States, although it is available in 90 other countries. "It will not be available in the United States, because the company is not asking the U.S. Food and Drug Administration to approve it," he said.
Tibolone is made by Organon, which is owned by Schering-Plough of Kenilworth, N.J. The company has decided not to try to get tibolone approved in the United States because of the increased risk of stroke, Cummings said.
Dr. Michael Strongin, a gynecologist at Lenox Hill Hospital in New York City, said, "All drugs that are being used for menopausal symptoms all have positives and negatives. The task is to find drugs that don't have problems."
"For the U.S. consumer, it's sort of a moot point," Strongin added. "It [tibolone] is not the magic bullet, but I think it's another drug that could potentially be used if it ever does get FDA approval. My caution would be that it's potentially helpful, but it's not a slam dunk that it's better than what we have been using."
To learn more about hormone replacement therapy, visit the U.S. Women's Health Initiative.