Hope for first human bone growth pill

Many elderly women develop brittle bones

Osteoporosis could eventually be treated by popping a pill which stimulates bones to grow, according to scientists.

Osteoporosis is a bone-wasting condition that affects many people over the age of 45, particularly women who have passed the menopause.

In the USA, some 15 to 20 million people are estimated to suffer from the condition which is thought to cost the US health system $3.8bn a year.

Normally, bone cells are continuously replaced. But in people with osteoporosis the old cells are eaten away and no new cells are generated.

This leads to a weakening in bone structure and susceptibility to fractures.

The usual treatments for osteoporosis all work to slow bone loss.

'Promising'

But US scientists say they have identified a chemical compound which could promote new bone growth.

Researchers from ZymoGenetics Incorporated, a Seattle-based biotechnology firm, say they have identified three compounds which stimulate bone growth in animals.

They told an American Chemical Society meeting on Sunday that early results look promising.

The compounds include two synthetic chemicals and a natural product.

Dr Nand Baindur of ZymoGenetics said: "This is the first report of small molecule drug-like compounds which have been shown to stimulate the formation of new bone in animals."

In the past, scientists have tried giving patients proteins that the body naturally uses to stimulate the formation of new bone cells.

But Dr Baindur says clinical trials of these have been inconclusive.

Cheap and easy to make

Moreover, he says proteins are big molecules which can only be given by injection, tend not to hold up well in the body and are fairly expensive to manufacture.

The small molecule compounds ZymoGenetics is developing are relatively inexpensive, easy to make and fairly stable.

He thinks they will eventually be available in pill form.

But no tests have yet been conducted on humans and it is likely to be some years before the products are on the market, if they are win clinical approval.

However, one of the compounds is already in clinical trials as a treatment for heart disease.