A daily dose of an investigational medication has been found to restore muscle mass in the arms and legs of older adults and improve some of their biochemistry to levels found in healthy young adults, suggesting an anti-frailty drug has been found.

The drug, called MK-677, was evaluated for its safety and effectiveness in a study that showed the drug restored 20 percent of muscle mass loss associated with normal aging. In fact, levels of growth hormone (GH) and of insulin-like growth factor I (IGF- I) in healthy seniors who took the drug increased to the levels found in healthy young adults, said Michael O. Thorner, a professor of internal medicine and neurosurgery at the University of Virginia Health System.

"Our study opens the door to the possibility of developing treatments that avert the frailty of aging," Thorner said. "The search for anti-frailty medications has become increasingly important because the average American is expected to live into his or her 80s, and most seniors want to stay strong enough to remain independent as they age."

Funded by the National Institutes of Health, the two-year, double-blind, placebo-controlled study involved 65 men and women ranging in age from 60 to 81. The results are detailed in the Nov. 4, 2008, issue of the journal Annals of Internal Medicine.

The drug mimics the action of ghrelin, a peptide that stimulates a growth hormone called secretagogue receptor (GHSR). Drug developers are focusing on GHSR because it plays an important role in the regulation of growth hormone and appetite. They think it may prove to be an excellent treatment target for metabolic disorders such as those related to body weight and body composition.

Drugs found to work in early trials don't always hold up to further testing, however.

The new research was a "proof-of-concept" study that sets the stage for a larger and longer clinical trial to determine whether MK-677 is effective in people who are frail and to assess its long-term safety.