Professor John Henry says strong prescription drugs can stop the natural breakdown of illicit drugs such as Ecstasy, causing them to remain in the body at deadly levels.

He describes the case of a man who died after combining an anti-Aids drug with Ecstasy.

Writing in The Lancet, Professor Henry says the 32-year-old man had taken Ecstasy before he started on the anti-Aids drug, ritonavir, with no ill effects.

Heart attack

In 1996, a year after developing Aids, he was put on triple combination drug therapy, including ritonavir.

In October 1996, he went to a club and took two and a half Ecstasy tablets.

About an hour later, he began to feel shaky and eventually suffered a heart attack and died.

An autopsy showed that he had very high levels of Ecstasy in his blood, much higher than would be expected given the amount of tablets he had taken.

Professor Henry, who works in the Academic Department of Accident and Emergency Medicine at Imperial College School of Medicine in London, says he believes ritonavir prevented the enzyme that breaks down Ecstasy from working.

He claims this is the first recorded case of a patient dying from using Ecstasy and an anti-Aids drug.

"It is a serious warning to people that they should not combine illicit drugs with certain medical drugs like anti-Aids drugs and some types of antidepressants," he said.

Blind eye

He claimed drug companies were reluctant to do tests on the effects of combining legal and illegal drugs and just assumed patients would not do so.

"Most drug companies do not want their names associated with illicit drugs. They are happier to turn a blind eye," he said.

He claims other medical drugs also stop the body's natural enzymes from breaking down illicit drugs, but Ecstasy was particularly effective at doing so.

An Aids patient died after combining Ecstasy with his prescribed drugs

He added that there was a wide variation in the way different people's bodies metabolised drugs.

For example, up to 10% of white people had low levels of the enzyme which breaks down Ecstasy so they were already at risk from the drug.

Professor Henry claimed this might go some way to explaining why some people can take the drug and suffer no apparent ill effects, while others may get very ill or die.

He added, however, that there were several other reasons for bad reactions to Ecstasy, such as dehydration.

Professor Henry says the public and doctors should be more aware of the dangers of mixing illegal and legal drugs.

And he called for drug companies to insert a warning about the potential risks.