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concentration can continue for months or longer after the drug use
has stopped.

On one level, opioid dependency is an adaptation of the body to
opiates. With repeated use, dependence develops when the body’s
various systems have adapted to the opioid where they require the
drug to regulate a physiological balance.

Methadone, as used in the treatment of opioid addiction, has an
affinity for mu opioid receptors in the brain where it blocks the
withdrawal syndrome and diminishes craving behaviors which
otherwise can lead to continued illicit drug use.

Of importance is the fact that at mu receptor sites, methadone will also
block the effects of other opioid drugs including heroin. This means
that even if a patient on methadone ingests heroin, the blocking effect
will disallow any heroin action and the patient is prevented from what
might have otherwise been a long and torturous relapse.

An Optimal Dose For Methadone Maintenance

There have been many research studies comparing various doses of
methadone for maintenance treatment. Reports have consistently
shown that patients receiving higher doses of methadone compared to
those receiving lower doses have much better outcomes – where
outcomes are defined in terms of abstinence from illicit opioid use,
length of treatment stay, and overall improvement in the quality of
life.

Essentially, all of the research on dosing has concluded that there is no
evidence of lower doses being adequate for the vast majority of
patients. Vincent Dole, one of the co-discoverers of methadone for
the treatment of opioid addiction, stated, "There is no compelling
reason for prescribing doses that are only marginally adequate. As
with antibiotics, the prudent policy is to give enough medication to
ensure success".
(see figure 5).