So what does all this have to do with methadone maintenance? None of it was known 32 years ago when Dole and Nyswander conceived the idea that a long-acting opiate might stabilize the neurochemistry and behavior of heroin addicts. Now, every professional care-giver who has treated heroin addicts properly with methadone knows how effective this medication can be.
Whether a heroin addict’s reward pathway was defective to begin with, or whether it was altered by the long-term insult of excessive dopamine release, it seems to function normally only if an opiate continuously occupies the mu opioid receptors. This continuous receptor occupancy is the stabilizing factor that permits addicts on methadone to normalize their behavior and to discontinue heroin use. It is, therefore, not correct to think of methadone as a “substitute” for heroin; its totally different pharmacokinetic properties make it, in effect, a completely different drug. It is true that both heroin (morphine) and methadone can occupy the mu opioid receptors. But the steady, stable occupancy by methadone contrasts sharply with the repeated excessive “highs” followed by excessive “lows” with heroin.
Methadone is not an experimental medication. It is more soundly based in biologic science and has been proved in more clinical trials than many drugs we use in modern medicine. It has helped hundreds of thousands of heroin addicts all over the world. It is safe and efficacious. Taken by mouth, it is well absorbed into the circulation, and it occupies the mu opioid receptors in the brain for about 24 hours. Its stabilizing action puts an end to the pattern of alternating “high” and “sick” several times a day that is typical for heroin addicts.
The effectiveness of methadone by mouth permits the addict to discontinue intravenous drug use, thus reducing the risk of hepatitis, AIDS, and other blood-borne infectious diseases. Quitting intravenous drug use is also the first step away from a set of bizarre anti-social behaviors.
When used properly, methadone allows a heroin addict to stop using heroin. It diminishes the craving for heroin, and by producing opioid tolerance it blocks the heroin “high”. Very important, if a patient on methadone does occasionally use heroin, that event need not become a relapse — it can remain a single episode, without significant consequences. In contrast, an abstinent ex-addict can almost never prevent a single “taste” of heroin from leading to a total relapse.
Methadone itself is a therapeutic aid, not a panacea. No magical interventions can stop a heroin addict from using, unless there is some motivation to stop. Thus, methadone must be accompanied by skillful counseling and rehabilitative aid, by psychotherapy as required (comorbidity with other mental illnesses is common), by job training if needed, by family involvement, and so on. Success requires a well-run program with well-trained staff, who understand that heroin addiction is a chronic relapsing disease, and who treat the addict with respect. The primary criterion of success is cessation of heroin use and of other drug abuse, as well as social rehabilitation. Giving up methadone eventually is realistic for some patients, not for others; it is certainly NOT a primary goal of treatment. As the underlying defect in the reward pathway has not been cured, there may well be addicts (we don’t know how many) who will require lifelong maintenance, much as diabetics requires insulin.