A U.K. study suggests supervised use of injectable heroin can be at least twice as effective as methadone at keeping addicts off street drugs. (CBC)

Supervised medical treatment with heroin leads to significantly lower use of street heroin by chronic addicts than does injected or oral methadone, according to a study to be published Friday in the medical journal, Lancet.

The randomized controlled trial involved heroin addicts who were receiving conventional oral methadone treatment but continued to inject street heroin regularly.

The study was conducted over six months by researchers at King's College in London, led by psychiatrist John Strang.

'Availability of heroin prescription can be dictated more by special interests and politics than evidence.'—Canadian experts quoted in heroin study

The researchers found that after six months, the patients receiving injectable heroin provided twice the proportion of urine samples that showed an absence of street heroin than the group treated with injectable methadone, and more then three times the negative samples than the oral methadone group.

Methadone relieves some craving for heroin addicts, but is an inadequate treatment for many chronic heroin users who often revert to illegal street drugs, according to some addiction experts.

"We have shown that treatment with supervised injectable heroin leads to significantly lower use of street heroin than does supervised injectable methadone or optimized oral methadone," the study authors said.

"Furthermore, this difference was evident within the first six weeks of treatment."

The authors also noted that the results are similar to six other randomized trials conducted in the U.K. in the past 15 years.

"Our work offers government robust evidence to support the expansion of this treatment, so that more patients can benefit," said Strang.

"Supervised injectable heroin should now be provided, with close monitoring, for carefully selected chronic heroin addicts."

Worldwide controversy

The issue of supervised heroin injection remains contentious in Canada, Australia, Switzerland and other countries where heroin trials have been halted or existing heroin support programs have been placed under threat.

A group of medical professionals from B.C. provided accompanying comment published in the study.

Supporters of medical facilities like the Insite clinic in Vancouver have had to put up political battles to stay open. (CBC)

"History tells us that availability of heroin prescription can be dictated more by special interests and politics than evidence," said the group, which included Dr. Thomas Kerr, Julio Montaner and Evan Wood of the B.C. Centre for Excellence in HIV/AIDS.

"In the era of evidence-based decision making, moving forward will probably need those embroiled in this debate to cast aside the stigma associated with heroin prescription," they said.

The Insite supervised drug injection facility in Vancouver has been the focus of controversy since it opened in 2003.

The Conservative government of Prime Stephen Harper has said it wants to withdraw legal sanctions from the clinic that allow it to operate in contravention of the Criminal Code. But the B.C. Court of Appeal ruled in January that Insite should remain open.

Insite does not provide heroin but provides medical supervision for addicts who inject street heroin in the facility.