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.

"Frailty is one of the scourges of elderly persons, and as researchers are beginning to learn about its causes, they are asking whether growth hormone deficiency is one of them," Dr. Michael O. Thorner, from the University of Virginia Health System in Charlottesville, and colleagues explain in the latest issue of Annals of Internal Medicine.

The promise of MK-677 is that it seems to restore growth hormone levels, they note.

In a "crossover" study, 65 healthy adults, between 60 and 81 years of age, received MK-677 or inactive placebo once daily for 1 year and then switched to the other treatment for 1 year.

Over 1 year, patients receiving the drug increased their growth hormone levels to those of healthy young adults, resulting in an increase in lean, fat-free mass.

MK-677 induced a transient increase in appetite. Body weight rose by 2.7 kg (5.9 lbs) with MK-677 treatment, but by just 0.8 kg (1.8 lbs) with placebo.

According to the researchers, treatment with MK-677 offset three factors that contribute to loss of muscle mass -- a hallmark of frailty, i.e., reduced growth hormone levels, loss of fat-free mass, and inadequate food intake.

The increase in fat-free mass seen with MK-677 therapy, however, did not translate into enhanced strength or function.

Nonetheless, "we believe that our study sets the stage for an adequately powered clinical trial of sufficient duration in a population vulnerable to frailty," the investigators conclude.