Compared with methadone, a commonly used drug used in heroin addiction treatment, diacetylmorphine led to 67 percent less illegal activity and illicit drug use after one year of treatment, compared to a 47.7 percent reduction with methadone, according to Dr. Martin Schechter of the University of British Columbia School of Population and Public Health in Vancouver and colleagues.
In addition, patients receiving diacetylmorphine had higher rates of retention in addiction treatment programs at one year -- 87.8 percent versus 54.1 percent -- the researchers reported in the Aug. 20 issue of the New England Journal of Medicine.
Schechter said methadone should remain the standard treatment for most patients with opioid dependence, with diacetylmorphine reserved for the 15 percent to 25 percent who don't respond.
"Methadone remains a pretty good first-line treatment," he said, "but either the switch to heroin or using heroin as an adjunct obviously has increased effectiveness for this difficult population."
Dr. Joshua Lee of New York University said the findings validate those from European studies -- that medical heroin is a valid approach to treating addiction.
"Generally," said Lee, who was not involved in the study, "it is a very positive development when a new treatment approach ... brings drug users into a medicalized, therapeutic environment where further treatment can be established and related problems like cocaine use can begin to be addressed."
Dr. Daniel Angres, psychiatrist and author of Healing the Healer: The Addicted Physician, questioned the usefulness of both diacetylmorphine and methadone as treatment options when an alternative with less abuse potential, bupronorphine, is available.
The drug is less likely to be abused, he said, because the naloxone would block the opiate effect of bupronorphine if the drug were injected.
To explore diacetylmorphine treatment in a North American population, Schechter and his colleagues initiated the North American Opiate Medication Initiative (NAOMI), an open-label, phase III trial conducted in Montreal and Vancouver.
The trial could not be conducted in the United States because of difficulty obtaining funding and regulatory permission to inject heroin, Schechter said.
Participants had been heroin users on average for 16.5 years on average, and they had at least two failed treatment attempts, one of which had to be methadone. About three-quarters had participated in illegal activities other than drug use in the month before the study began.
The researchers assigned 111 participants to methadone and 115 to diacetylmorphine, which was self-administered up to three times daily with a maximum daily dose of 1,000 milligrams. Treatment lasted one year.
By the end of treatment, composite scores for drug use and illegal activities on the European Addiction Severity Index improved significantly in both groups.
Patients who received diacetylmorphine had significant improvements on six of the seven remaining subscales. Those who received methadone improved on two -- economic status and employment satisfaction.
The gains in the diacetylmorphine group were greater than those in the methadone group for drug use, psychiatric status, employment satisfaction, and social relations.
There were more serious adverse events in the diacetylmorphine group -- 51 versus 18. None of the adverse events in the methadone group was attributed to the study treatment.
The most common serious adverse events with diacetylmorphine treatment were potentially life-threatening overdoses in 10 patients and seizures in six. None of the patients died.
"Our safety data suggest that diacetylmorphine should be delivered in settings where prompt medical intervention is available," the researchers said.
Schechter added, however, that "we consider the results to show it's very, very safe."
Diacetylmorphine treatment is more expensive than methadone, Schechter said. A year of treatment costs about $6,300 to $7,300 for prescribed heroin and about $2,700 to $3,600 for methadone.
But, he said, with the cost of an untreated person with heroin addiction estimated at about $50,000 a year -- including costs associated with medical care, imprisonment, and legal proceedings -- both treatments appear highly cost-effective.
A formal cost-effectiveness analysis is ongoing, he said.
In an accompanying editorial, Virginia Berridge of the London School of Hygiene and Tropical Medicine, pointed out that European countries that have conducted similar trials have had different responses to the results, partly because of the politics and controversial nature of the treatment.
For example, she said, Switzerland and the Netherlands have begun prescribing heroin as part of their medical system, whereas Germany and Spain have balked at the idea.
"We will now wait to see what political or professional factors will support or oppose the conclusions of this study in its home territory, and whether the historical legacy of heroin will matter," she said.