Tibolone is known to increase mineral density, a sign of bone strength, and to alleviate hot flashes and other menopausal symptoms. But doctors have worried that its tendency to reduce high-density lipoprotein, or "good" cholesterol, could result in heart vessel disease. The Wake Forest researchers found that even though tibolone lowered HDL by half, there was no increase in vessel disease. "Our results suggest that tibolone is a cardiovascular-safe treatment for menopausal symptoms as the prevention of osteoporosis," said Thomas Clarkson, D.V.M., professor of comparative medicine at Wake Forest and the study's lead researcher.
The two-year study of 150 postmenopausal monkeys compared two different doses of tribolone, estrogen (Premarin), and estrogen combined with progestin (PremPro). A fifth group of monkeys received no drug treatment. The monkeys received drug doses designed to approximate the levels women are normally prescribed. They were fed a moderately high-fat diet (42 percent of calories from fat) designed to speed up the development of vessel disease.
"We found that both Premarin and PremPro had a robust cardiovascular protective effect, but there was no such protective effect from tibolone," said Clarkson. "On the other hand, we found that tibolone may have advantages over Premarin and PremPro for breast and uterine safety."
Bone mineral density increased by 9.5 percent in the group receiving the high dose of tibolone, 4.5 percent in the PremPro group, and 4.3 percent in the Premarin group. PremPro and Premarin both reduced corona
Contact: Karen Richardson
Wake Forest University Baptist Medical Center