News

Many heart patients are ending up in hospital with intestinal bleeding because they are needlessly taking too high a dose of acetylsalicylic acid, a new study suggests.

ASA, better known by its brand name Aspirin, is routinely prescribed to heart patients because it inhibits the formation of blood clots, which can trigger heart attacks and strokes.

However, prolonged use of this highly effective drug can also cause serious bleeding, especially in the gastrointestinal tract.

Doctors generally recommend a daily dose of either 81 milligrams (equivalent to a "baby Aspirin") or 325 mg (a standard adult dose).

A team of international researchers decided to determine the most effective - and least risky - tablet to take.

By reviewing previously published trials, the researchers concluded the low dose is the best bet for most patients. "There is no evidence that higher doses of Aspirin will protect you from cardiovascular events (heart attacks or strokes) any better than lower doses," said the study's lead author, Charles Campbell of the University of Kentucky College of Medicine. What's more, the higher dose is clearly "associated with more bleeding," he said.

The new study, published in this week's edition of the Journal of the American Medical Association, estimated that 250,000 patients in the United States are hospitalized annually because of bleeding complications from Aspirin. That figure suggests there could be 25,000 similar cases in Canada each year.

Meanwhile, in a separate study being published today in The Lancet, British researchers found that 300 mg or more of Aspirin a day can help prevent colorectal cancer.

But because of the elevated chance of bleeding, experts still think it's unwise for healthy people to take it daily. "If you have no evidence of any increase in risk of colorectal cancer ... then it's probably not worth taking on the basis of cancer prevention alone," said the study's lead researcher, Peter Rothwell at Oxford.

HRT alternative

Millions of menopausal women suddenly stopped taking hormone replacement therapy five years ago, when a major study linked the popular treatment to an elevated risk of heart disease and breast cancer.

Since then, pharmaceutical companies have been busy trying to develop "non-hormone" treatments to fill the void.

At a scientific meeting in San Diego this week, several studies were presented on the leading contender - Pristiq, an experimental drug that appears to diminish the hot flashes and night sweats experienced by many menopausal women.

Pristiq is derived from an existing antidepressant medication, Effexor, made by Wyeth Pharmaceuticals. Pristiq affects the balance of two brain chemicals - serotonin and norepinephrine - that are believed to play a role in regulating body temperature. Research indicates that hot flashes might be caused by changes in serotonin levels during menopause.

The latest Pristiq studies suggest the new drug might not be as effective as HRT in controlling menopausal symptoms. But the hope is that the non-hormonal treatment will be a potentially safer option.

Wyeth is going through the drug approval process in the United States.

Chelation therapy tested

Canadian researchers are recruiting patients for a study of chelation therapy - a controversial treatment for heart disease.

The treatment is meant to strip heavy metals from the bloodstream and remove calcium from the plaque in blood vessels. It is popular in alternative medicine circles, and patients pay thousands of dollars to have it done. But many doctors are leery of the treatment, saying there is not enough evidence to prove it works.

To settle the issue, the U.S. National Institutes of Health has launched a $30-million (U.S.) international study. Clinics across Canada are joining the research effort, which will involve 2,400 heart disease patients.

"It should put an end to controversy ... by showing whether chelation therapy makes a difference or not," said Dr. Richard Nahas, founder of the Seekers Centre for Integrative Medicine in Ottawa.

Information on Canadian trial centres can be found at http://nccam.nih.gov/chelation/studysitecan.htm.ptaylor@globeandmail.com