How effective is coated aspirin?

New studies have revealed a significant drop in the effectiveness of aspirin in recent years, and an increase in resistance to the drug.

Research has found that the protective coating on mini aspirins decreases their absorption and may reduce their ability to prevent strokes and heart attacks. Aspirin was also found to be less effective because the incidence of aspirin resistance has increased, while doctors are prescribing decreasing doses of the drug to avoid causing stomach bleeding.

Researchers at the Royal College of Surgeons in Dublin conducted trials to compare the efficacy of 3 aspirin preparations. They tested whether the aspirin would reduce the effectiveness of the chemical that causes the blood to clot.

They found that plain uncoated aspirin was the most effective.

The research team also examined how well the aspirin was absorbed by the body. The tests showed that uncoated aspirin was absorbed most effectively in the stomach, but that coated aspirin was released after passing through the stomach. This means that a higher dose of coated aspirin is required for the drug to be most effective.

Other findings showed that every 10-kg increase in weight resulted in an approximate doubling of risk of treatment failure with the coated aspirin. This may be an explanation for the increasing incidence of aspirin resistance.

The researchers concluded that to ensure aspirin is effective, a plain 75mg dose or 100mg of coated aspirin should be taken.

Remember: Speak to your GP before changing your medication.

Source: Stroke 2006; 37:2153-2158.
http://stroke.ahajournals.org/cgi/gca?allch=&SEARCHID=1&FULLTEXT=aspirin+coating&FIRSTINDEX=0&hits=10&RESULTFORMAT=&gca=strokeaha%3B37%2F8%2F2153&allchb=