Growth hormone stimulator may combat frailty

NEW YORK (Reuters Health) - An experimental drug that stimulates the body to secrete growth hormone boosts lean muscle mass and physical function in older adults, perhaps combating physical weakness or "frailty," according to results of a study.

As people age, the decline of growth hormone secretion in the body may play a role in the development of frailty, the debilitating loss of fat and muscle tissue.

In the study, 395 men and women aged 65 to 84 years with mild physical limitations were randomly assigned to placebo or one of four doses of Pfizer's experimental growth hormone stimulator called capromorelin.

A total of 315 subjects completed 6 months of treatment and 284 completed 12 months. Based on these data, all four doses of capromorelin produced a sustained increase in insulin-like growth factor I -- a hormone involved in growth and development.

Dr. Heidi K. White, of Duke University Medical Center in Durham, North Carolina and colleagues also observed a significant increase in lean body mass with capromorelin and improvements in two physical performance tests -- tandem walking (heel to toe) and stair climbing.

"These findings support our hypothesis that stimulating growth hormone production not only increases the body's ability to develop lean muscle, it also restores physical functioning," White noted in a university-issued statement.

"The improvements seen in this study are promising but relatively mild, likely due to the general good health of the study participants," she added. "Further research is warranted to determine if greater improvements in physical functioning are seen among people who are already somewhat frail."

"Following further investigation," suggested White, "capromorelin could be used in combination with exercise" to combat frailty associated with aging.

SOURCE: Journal of Clinical Endocrinology & Metabolism, April 2009.