Dec. 2, 1999 (Washington) -- Just as drugs for prostate and heart problems w
Dec. 2, 1999 (Washington) -- Just as drugs for prostate and heart problems were found to spur hair growth, researchers in Texas have discovered that some cholesterol-lowering medications produce new bone. If tests on humans prove as successful, the medications, called statins, may be effective in treating osteoporosis, which causes pain and fractures in an estimated 30 million Americans.
Researchers tested more than 90,000 chemical and natural compounds to see if any would activate a particular gene that stimulates the growth of bone cells. They were about at the end of their list when one -- Mevacor (lovastatin) -- came up a winner, so they tested it and three other statins in a series of experiments in mice and rats. There are six statins on the market today for the treatment of high cholesterol; they are sold under names such as Zocor (simvastatin) and Pravachol (pravastatin).
They added lovastatin and four others in the same statin class to the cells of mice, injected them into the skin covering the skull of mice, and gave them orally to rats, including some whose ovaries were removed to simulate menopause. The most dramatic result came from injections, which caused bone cells to grow by nearly 94%, while the other methods produced an increase in bone mass and cell volume of up to three times what existed before the statins were added.
The researchers were led by Gregory Mundy, MD, PhD, professor of medicine and chief of the endocrinology division at the University of Texas Health Sciences Center at San Antonio. He completed the research with colleagues at the university and at Osteo Screen, a 15-employee, for-profit research firm he established in 1996. Mundy tells WebMD he's now at work on a patch that can deliver statins more directly to bone.
"I think we have enough data now that it would be worth doing [studies on humans,] but I would prefer that that be done by somebody separate from me," says Mundy, adding that trials would require tens of millions of dollars. "What I'm hoping is that this will stimulate others to do the trials. Our next step is to optimize the current statins to get them effectively to bone. ... We've just got to find the most optimal ways," including topical agents like a transdermal patch. "People don't want to take injections, and they are expensive as well."
The bones in people with osteoporosis, particularly postmenopausal women, become fragile and brittle. Physicians today have several osteoporosis treatments at hand, but some produce gastrointestinal side effects severe enough for patients to abandon the therapy, and none causes more than a modest increase in new bone growth. Medications approved today -- including estrogen, Foxamax (alendronate), and Evista (raloxifene) -- work by halting bone loss or reabsorption. A recent study showed Actonel (risendronate) increased bone density and reduced fractures with fewer side effects. Now used to treat Paget's disease of the bone, where bones become both thickened and softened, risendronate is expected to win FDA approval for treatment of osteoporosis in spring 2000.
Nelson B. Watts, MD, is lead author of a study appearing two months ago in The Journal of the American Medical Association that showed the effectiveness of risendronate in reducing fractures. He lauded the results of this new study. "It looks good to me," says Watts, who reviewed the study for WebMD. "All of us have been eagerly awaiting a drug that we can use clinically that will stimulate new bone formation. It is still a long way from [testing on humans] but it is still a very impressive result that begs to be pursued."
The volume of new growth observed "is really quite impressive," says Watts, who is with Emory University. "It would be awfully nice to have drugs that increase the bone density more than the 5-10% we have now."
Vital Information:
- Some cholesterol-lowering medicines, called statins, may also be effective in treating osteoporosis, according to a recent animal study.
- There are several approved medications for osteoporosis, but their effect on bone growth is modest and side effects can be so severe that patients stop taking them.
- Statins had a more dramatic effect on bone mass, but these results are preliminary and further testing should be done.
