Human Parathyroid Hormone Could Be Potent New Therapy.(for osteoporosis)

2001 JUN 7 - (NewsRx Network) -- A substance secreted by four tiny glands in the neck could provide the most powerful treatment to date for osteoporosis.

In the May 10, 2001, issue of the New England Journal of Medicine, a Massachusetts General Hospital (MGH) researcher working with scientists elsewhere reported that postmenopausal women with osteoporosis who took daily doses of human parathyroid hormone had significantly fewer spine and nonspine fractures. By promoting bone formation, the hormone also significantly increased bone density in their spine, hip, and total body.

"The key to parathyroid hormone's fracture-thwarting powers is that it stimulates bone formation dramatically: it doubles the normal rate," says Robert Neer, MD, director of the Osteoporosis Center at MGH.

Currently available osteoporosis treatments slow bone resorption and bone loss. In contrast to these anti-resorption drugs, parathyroid hormone promotes bone formation. The study showed that after 21 months, the women taking parathyroid hormone had up to 13% more bone in their spine than those taking placebo. The average increase in bone for women taking currently available drugs is 9% or less, after two to three years of treatment.

The effect can be illustrated by a half-filled glass of water with a hole in the bottom. Current drugs concentrate on slowing the leak, but parathyroid hormone acts by replenishing the water at a greater rate than is lost through the leak.

Neer was principal investigator in the international clinical trial sponsored by Eli Lilly and Company. Working with 99 investigators in 17 countries, the team enrolled 1,637 postmenopausal women with osteoporosis. None of the women were taking other prescription drugs for osteoporosis, and each was placed on one of three regimens: placebo, 20 or 40 micrograms ofparathyroid hormone injected subcutaneously each day.

"Parathyroid hormone reduces the percentage of women with osteoporosis who develop a new vertebral fracture by 65% and 69% [for the two doses, respectively]. No other drug has reduced it more than 40% to 50%," says Neer.