New findings on aspirin's benefits

Aspirin has long been recognised as useful in reducing the risk of blood clots that can lead to heart attack and stroke. Research in the US by a senior Irish scientist has now shown that the pain killer might also help reduce hardening of the arteries.

Work by the University of Pennsylvania School of Medicine has shown that aspirin, ibuprofen and related "non-specific COX inhibitors" may help prevent heart disease by slowing the build up of plaque in blood vessels by more than 50 per cent.

The study was done by Prof Garret FitzGerald, chairman of the university's department of pharmacology in co-operation with Dr Domenico Pratico, a research assistant professor of pharmacology at Penn and colleagues. The results are published this week in the US Proceedings of the National Academy of Sciences.

Drugs such as aspirin work by inhibiting an enzyme known as COX1. The enzyme occurs in many cells including platlets, the blood cells responsible for clotting. It has already been established that blocking COX1 helps to reduce the likelihood of spontaneous clots, the cause of many heart attacks and strokes.

Prof FitzGerald has worked for many years on the action of COX1 and a similar enzyme, COX2. This study examined both forms of the enzyme in an effort to understand the role either might play in hardening of the arteries or atherosclerosis.

Hardening of the arteries occurs when plaque deposits build up along the inside walls of blood vessels. This narrows blood flow through the vessel, increasing the risk of blood clots that cut off the flow entirely. The plaques are associated with cholesterol from eating a diet high in fats.

The team used mice that had been engineered to produce high levels of cholesterol, which in turn caused significant plaque deposition. Groups of mice were given a non-specific COX inhibitor, a COX2 inhibitor and a placebo was given to a control group. The key finding was that the mice who received the non-specific COX inhibitor had greatly reduced levels of atherosclerosis, which were 55 per cent below the control group.

"This study suggests that a product of the cyclooxegenase enzyme known as COX1, which is the form targeted by aspirin in the prevention of heart attacks, may also have a part to play in the gradual hardening of the arteries that precedes acute events like heart attack or stroke," Prof FitzGerald said.