Bone builder: drug may offer steroid users new protection against fractures.

In the half-century since their introduction to medicine, glucocorticoid steroids have been hailed as wonder drugs that have enabled millions of people to combat rheumatoid arthritis, severe asthma, autoimmune diseases, and organ-transplant complications. But the drugs have some serious risks, notably the bone-loss disease osteoporosis. The steroids hamper--and may even kill--bone-building cells.

To stop bone loss, many people take drugs that preserve existing bone, but a newer drug, teriparatide (Forteo), activates bone-building cells instead. A new study finds that boosting bone growth may be the more effective choice for longtime steroid users who have developed osteoporosis.

Scientists enlisted 428 people who had steroid-induced osteoporosis and randomly assigned half to receive teriparatide. The others got alendronate (Fosamax), a drug that preserves bone mass. Average ages in the two groups were 56 and 57, respectively. The Food and Drug Administration (FDA) has approved both drugs for osteoporosis but has not cleared teriparatide for steroid-induced bone loss.

After 18 months, 150 patients had maintained their teriparatide treatment and 144 had completed their alendronate treatment. During the study, 1 person on teriparatide and 10 on alendronate had vertebral fractures. Moreover, patients getting teriparatide had increases in hip and vertebral bone density that were significantly greater than such gains in people getting alendronate, the researchers report in the Nov. 15 New England Journal of Medicine.

"For steroid-induced osteoporosis, teriparatide appears to be a better drug," says Robert Adler, an endocrinologist at Virginia Commonwealth University and the McGuire Veterans Affairs Medical Center in Richmond, who contributed data to the study.

At the cellular level, the findings suggest that teriparatide is blocking the biological mechanism by which steroids thwart bone formation and lead to fractures, says study coauthor Kenneth G. Saag, a physician and epidemiologist at the University of Alabama at Birmingham.

In postmenopausal women, osteoporosis develops gradually over several years, but in people taking steroids, it can appear after as little as 3 months, Adler says.

"Many of us believed that [teriparatide] would be a better treatment, but we didn't have the evidence to support that," says Michael R. McClung, an endocrinologist at the Oregon Osteoporosis Center in Portland.

Eli Lilly, the company that makes teriparatide, funded the new research. In 2002, the FDA approved the drug for limited use in postmenopausal women at high risk of fracture. Earlier studies in rats had linked teriparatide with a rare bone cancer, but no signs of that have shown up in people using it. Even so, the drug comes with a "black box" warning on its label noting this potential risk. As part of the regulatory-approval agreement, Lilly agreed to fund a long-term study monitoring patients for signs of the bone cancer.

On the basis of the new study of steroid users, MeClung expects regulatory approval of teriparatide for patients who use steroids regularly. "This is exactly the kind of information that the FDA requires" in sanctioning a new use for a drug, he says.

It would seem tempting to combine the two drugs, so that one could build bone while the other preserves it. However, earlier tests suggested that bone preservers blunt the bone-growth effects of teriparatide, MeClung says.