Addiction specialists are delighted
that the opioid dependence drug buprenorphine finally
became available last month after getting the green
light from Health Canada in May. The drug, hailed by
some as a potential replacement for methadone, is a
sublingual pill with milder side effects that can be
prescribed by GPs.
"The availability of buprenorphine
in Canada is a part of a long-awaited solution to our
need for a new treatment option for our patients," said
Vancouver addiction doctor David Marsh. "It's important
to have a new choice, and arming physicians with another
weapon to fight opioid dependence will only serve to
help patients manage this disease."
In the US, where the drug has been
available since 2000, buprenorphine has already become
the most frequently prescribed therapy for opioid addiction.
But the drug can cost up to ten times more than methadone.
In Canada, the drug won't be covered on provincial formularies
for a while. Dr Marsh told The Province it's
as yet only available to BC patients who can afford
it, which leaves most addicts out in the cold.
THE
BUPE ADVANTAGE
Unlike methadone, buprenorphine is a partial opioid
receptor agonist, so it gives less of a high to patients.
This also slashes the risk of overdose, according to
a Swedish study in May's American Journal of Psychiatry.
The study compared buprenorphine and methadone as first
line options and found the success rate was very similar.
But buprenorphine has a slew of safety features that
gives it an edge as first line treatment, concluded
study authors. For one, the tablet combines buprenorphine
with naloxone, a chemical that causes severe withdrawal
symptoms if it's misused. In other words, when patients
take the pill under the tongue as they're supposed to,
naloxone gets broken down in the GI tract and nothing
happens. But if they try to mash the pill and inject
it, they'll be hit with withdrawal symptoms like tremors.
Another advantage of buprenorphine
is its long-lasting effects. It allows doctors to adjust
the dosage so patients can take it every two or three
days, as opposed to the daily dosing necessary with
methadone. Patients can also eventually take home doses
of buprenorphine, something unheard of in methadone
treatments.
But perhaps the most significant
benefit of buprenorphine is that it gives patients greater
access to treatment, without having to go to specialized
clinics as required with methadone, which are rare outside
large cities and often have long waiting lists. Doctors
can prescribe the drug in-office, without a Health Canada
exemption. A recommended CME course, accredited by the
College of Family Physicians of Canada, is already available
(call 1-800-463-5442 or visit www.suboxoneCME.ca).
THE
BUPE WEAKNESSES
But what of the more heavily addicted patients? ask
Australian docs Andrew Byrne and Alex Wodak in a letter
to the editor in November's American Journal of Psychiatry,
in response to the Swedish study. More than half the
buprenorphine patients in the comparison study were
eventually switched to methadone, they point out. For
them, buprenorphine was less effective than methadone
— for the very same reasons that made it safer.
The maximum approved daily dose
of buprenorphine is 32 mg, which is approximately equivalent
to 70 mg of methadone, write the study authors. But
optimal doses of methadone are around 100 mg per day,
and some patients need up to 140 mg/day during their
treatment process. So patients who were long-term addicts
eventually "outgrew" buprenorphine and were switched
to methadone.
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