Cholesterol-lowering drugs may lead to osteoporosis treatments
December 3, 1999
Web posted at: 2:51 PM EST (1951 GMT)
By Sarah Yang
(WebMD) -- Commonly prescribed cholesterol-lowering drugs can stimulate new bone formation in animals, according to a study published this week in the journal Science. The results point toward a new direction for research into osteoporosis treatment for humans.
A research team, led by Gregory Mundy, M.D., president of the bone research company OsteoScreen, found that a class of drugs called statins doubled and tripled new bone formation in laboratory cultures. Tests in live mice and rats showed that two statins, simvastatin and lovastatin, increased new bone formation by almost 50 percent when injected into the tissue surrounding the skullcap. When taken orally for 35 days, simvastatin increased bone growth by 39 to 94 percent.
"This notion represents a big step forward from the current drugs on the market," said Mundy, who heads the division of endocrinology and metabolism at the University of Texas Health Science Center in San Antonio. Instead of just halting or slowing bone loss, which is what current treatments do, statins may actually build new bone.
Estrogen replacement therapy, raloxifene and alendronate are some of the major treatments used today to treat and prevent osteoporosis, a bone-thinning disease that affects 10 million Americans and threatens 18 million more.
Other drugs that build new bone are currently being tested on humans. But so far none of them has been proven safe and effective or approved by the Food and Drug Administration. Statins on the other hand are a "remarkably safe" class of drugs, says Mundy, that have been prescribed for millions of Americans over the past decade. Statins target an enzyme in the liver and prevent fatty acids from converting into cholesterol.
Conrad Johnston, M.D., president of the National Osteoporosis Foundation, says Mundy's findings open up new avenues in bone research, which are likely to become increasingly important in the coming decades: The foundation predicts that the number of people with low bone mass will reach 41 million by 2015, propelled by the aging of the "baby boomer" generation. Older, post-menopausal women are at greater risk for developing osteoporosis, which contributes to 1.5 million bone fractures annually. Other contributing factors can include smoking, alcohol abuse, a diet low in calcium, a sedentary lifestyle and certain medications such as corticosteroids.
Study may not lead to treatments
Encouraging as the results may be, scientists caution that it will be many years, if ever, before this study leads to human treatments. "The statins used now in clinical practice tend to target the liver rather than bone," says Steven T. Harris, M.D., chief of the osteoporosis clinic at the University of California, San Francisco. "The concentrations achieved in bone are relatively small" and not likely to have an effect, he says.
Another warning is sounded by a researcher from Merck and Company, the manufacturer of the osteoporosis drug alendronate, brand name Fosamax, as well as the cholesterol drug simvastatin, marketed as Zocor. "The doses used in the study are extremely high" -- several times greater than current human doses -- says John Yates, M.D., executive director of clinical research at the Merck Research Lab in New Jersey. Increasing the dose would be risky, Yates warns: All statins have been shown to be potentially toxic in certain kinds of muscle tissue.
A drug that stimulates bone growth is a tantalizing possibility -- "the holy grail of bone researchers," says Yates. But studies on simvastatin in thousands of men and women have not yet shown any significant benefit for bone health, either in reduction of fractures or in the stimulation of osteoblasts, the building blocks of bone.
More research needed
Mundy acknowledges these potential barriers and doesn't approve of the use of statins for osteoporosis in humans at this time. But he says there may be statins that drug companies haven't marketed because they weren't effective at reducing cholesterol; these statins could be considered for promoting bone growth. At the very least, says Mundy, the study provides a solid starting ground for further research.
Copyright 1999 WebMD, Inc. All rights reserved.
RELATEDS AT :
National Osteoporosis Foundation
The Foundation for Osteoporosis Research and Education
The Health Science Center at San Antonio
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