Few countries
have embraced methadone maintenance therapy more readily
than Canada.
Even though
most of the opioid addiction programs are run by the
provinces, the federal government recognized early on
that almost any alternative is preferable to street
heroin use. Their attitude is hardly surprising, given
that one untreated illicit opioid user costs the healthcare
system $49,000 a year, compared to about $6,000 for
methadone maintenance, according to research cited by
Health Canada. But the safety and cost-effectiveness
of opioid substitutes could be improved further, says
a study published in Addiction last month that compares
methadone to the analgesic dihydrocodeine.
SCOT-FREE
The study comes from Scotland — a country where
opiate addiction is as much of a problem as in downtown
Vancouver. Dr Roy Robertson of Edinburgh University
and colleagues followed 235 patients, randomized into
methadone and dihydrocodeine groups, for three and a
half years.
For about
half the cost, and with a comparably low rate of side
effects, dihydrocodeine in pill form achieved almost
identical results to methadone in six key measures:
survival, retention in treatment, continued drug use,
criminal behaviour, and physical and psychological health.
The only death occurred in the methadone group.
But, Dr
Robertson warned, this doesn't mean that dihydrocodeine
should become the new gold standard. "Just as with other
chronic conditions there should be a number of treatments
available so that doctors and nurses can tailor medication
to the needs of each patient," he said in a press release.
Methadone should still be used to treat the majority
of patients, he added, but dihydrocodeine offers an
alternative treatment for those who can't tolerate it,
or find it hard to deal with the stigma of having to
take their dose — sometimes every day — in
a pharmacy. It's also much cheaper.
One in 300
Canadians is addicted to some form of opioid.
DARE
TO COMPARE
Dihydrocodeine is hardly a novel or experimental drug.
Developed in Germany a century ago as an antitussive,
it has many applications in pain control. It has even
been used as an opiate addiction maintenance drug before
— especially in prison settings where rules often
forbid methadone to inmates who weren't on a program
at the time of incarceration — but it has never
really gone head-to-head with methadone in a controlled
study until now.
In fact
most of the attention, in both Britain and Canada, has
been focused on another potential methadone alternative:
buprenorphine, growing in popularity among British addiction
experts and approved last year in Canada.
Like dihydrocodeine,
buprenorphine compares to methadone in head-to-head
efficacy trials. And like dihydrocodeine, it's a pill.
But when buprenorphine was piloted in France, prescribing
rules were a little lax, allowing patients to take several
pills home at a time. The result was that many crushed
several at a time and injected them. The same problem
arose in an Australian program.
While patients
can do the same with dihydrocodeine they're likely to
find it considerably less rewarding than buprenorphine
in psychoactive terms. Our government has also learned
from the mistakes of France and Australia and is regulating
prescribing much more tightly.
METHADONE
CHALLENGE
Of course, all these comparisons still leave wide open
the question of whether doing as well as methadone is
actually good enough. Scotland's methadone program has
come under fire recently, after research by Neil McKeganey
of the University of Glasgow suggested it was having
almost no impact on crime rates and drug offences, despite
a steady increase in the number of people enrolled in
the programs. Three years after beginning methadone
treatment, just 3.4% of the 695 addicts interviewed
for his report were completely drug-free, compared to
29% of those who had gone cold turkey in residential
rehab.
But supporters
of methadone maintenance argue that this misses the
point. Staying on methadone, they say, is not a sign
of failure but of success. The rise of HIV and hepatitis
C among IV drug users gives powerful impetus to this
argument.
It certainly
convinces Dr Robertson: "We want to engage young people
in a treatment program which stops them from injecting
drugs and running the risk of infection," he said. "We
face an epidemic of hepatitis C in Scotland, with 40%
of young people who have been injecting drugs for more
than two years being infected with this serious illness."
It could be worse — the 2001 Vancouver Injection
Drug Users Study found HIV and HCV rates of 11.1% and
52.1% respectively in addicts aged under 24.
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