Bone density hope for womenBy Graeme O'NeillFebruary 12,...

Bone density hope for women

By Graeme O'Neill
February 12, 2006

EXPERIMENTS in the US suggest an anti-obesity drug developed by Monash University researchers might have an unexpected benefit — preventing osteoporosis in post-menopausal women.

Researchers at New York's Mount Sinai Hospital removed the ovaries of female rats to simulate the effects of menopause in human females, and gave them a daily dose of the experimental drug AOD9604.

The drug reduced average weight gain in the rats by around 50 per cent while maintaining their bone mass and density.

The new treatment emerged from nearly three decades of research by a Monash University biochemist, Professor Frank Ng, into the human growth hormone (hGH). A Melbourne drug manufacturer has made a drug that mimics some of the effects of the hormone.

Released by the pituitary gland in the brain, hGH is effectively three hormones in one. It regulates the balance between muscle and fat; influences sensitivity to insulin — a key factor in diabetes; and stimulates milk production in all mammals.

Melbourne's Metabolic Pharmaceuticals is trialling two versions of the drug. The first, for obesity and possibly osteoporosis, is already in a phase 2 clinical trial as an orally delivered therapy; the second is still undergoing pre-clinical trials as a potential treatment for type 2 diabetes (a form of diabetes common in overweight or obese individuals in which cells become resistant to insulin).

Metabolic's CEO, Dr Roland Scollay, said the hormone reduces obesity by tipping the body's metabolic balance towards producing lean muscle tissue instead of fat; and it also has direct effects on bone density.

In the US study, researchers dosed the female rats daily with 50 milligrams of the drug. They found that, in addition to reducing weight gain, it completely prevented loss of bone mass and density.

"They made comprehensive measurements of bone strength, including mass, mineral density and resistance to different types of fractures," said Dr Scollay.

"We had predicted this result, based on laboratory experiments, which showed that AOD9604 directly stimulates osteoblasts, the specialised cells that rebuild bone."

Dr Scollay said Metabolic, after further studies to determine the optimal dose, planned to take AOD9604 to human trials as an osteoporosis therapy.

The rats were treated with a relatively high dose. Dr Scollay said the company needed to determine whether it was also effective at a low dose.

Dr Scollay said that, in 2004, the global market for osteoporosis drugs was estimated at $US4 billion and was rising steeply as increasing numbers of baby-boomer women entered menopause.

He said obesity and osteoporosis are linked: vigorous exercise stimulates production of hGH, resulting in a lean, muscular body and improved bone mass and density.

Levels of the hormone decline steeply after the first two decades of life, a time when people become increasingly sedentary, gain weight as fat and lose bone density.