Study: New Osteoporosis Drug Replaces Bone

B O S T O N, May 9 -- The first osteoporosis drug to replace lost bone instead of merely stopping additional bone loss could be available by the end of this year, says the drug's manufacturer, Eli Lilly.

The new drug — to be called Fortéo — is a daily injection of human parathyroid hormone (PTH) produced by genetically engineered bacteria.

PTH normally is secreted by the parathyroid glands in human beings. The hormone controls bone formation and the excretion of calcium and phosphorus.

Researchers say the drug version of PTH stimulated new bone growth, reducing the risk of repeat backbone fractures in women with osteoporosis by 65 percent to 69 percent, depending on the dose. Risk of fracture elsewhere in the body was reduced by approximately 50 percent.

The study appears in this week's New England Journal of Medicine and was sponsored by manufacturer Eli Lilly. A New Drug Application has been filed with the FDA and awaits approval. Lilly has also formed partnerships with two other companies to develop inhaler and pill forms of the drug.

Drug Has Bone-Growth Potential

Experts interviewed by ABCNEWS.com expressed excitement about the bone-building potential of PTH.

"This is the first bone active agent that works on bone formation and not just slowing bone breakdown — so it has a totally different mechanism of action from the other approved drugs for osteoporosis," says Joan McGowan, director of the musculo-skeletal diseases branch at the National Institutes of Health.

Bone mineral density in the spine increased by 9 percent for the 20 microgram dose and 13 percent for the 40 microgram dose.

Dr. Hunter Heath, medical director, of the U.S. endocrinology division at Eli Lilly, said the best candidates for parathyroid hormone would be like the women in the study, who were around age 70, and had at least one previous osteoporosis-related fracture. "This wouldn't be for prevention," he says.

However, once a convenient pill or inhaler is developed, people will be more willing to use PTH and it could be used as prevention, says Dr. John Potts, director of research at Massachusetts General Hospital, an independent researcher commenting on the study.