[Pharmaco-clinical aspects of methadone. Literature review of its importance in treatment of substance dependence].

In order to assess the initial hypotheses of Dole, who set the objectives of methadone maintenance in 1966, this article reviews all research findings available in the field. The side-effects of methadone appear rather infrequent with few long lasting effects. The selection of a dose sufficiently high to block opiat receptors seems make the patient little or not sensitive to heroin intake whereas treatment compliance seems to be dose-related until a plateau of about 120 mg/day. All studies show a dramatic decrease in heroin intake. In contrast, a change in the drug use profile toward an increase in alcoholism and cocaine intake appears in certain subjects. Regarding AIDS, results seem less clear, showing a global decrease in intravenous use as behavior at risk but providing apparently not a total protection unless complete discontinuation. The decrease in antisocial behavior appears clearly, interpreted as a decrease in the economic pressure on the consumer. As a consequence of these results, an assistance in social rehabilitation appears more effective. Whereas the literature regarding withdrawal clearly shows the usefulness of the technique regarding the duration and the persistence of withdrawal symptoms, it remains very blurred regarding long-term results. The average age (about 30 years) and the average duration of drug abuse (about 10 years) of the patients included in those studies lead to the conclusion that only a marginal part of the total population is taken in charge, meaning that these techniques will never be solutions to a problem of society but only individual therapies. This article also raises the problem of the passionate climate associated with these issues--with negative consequences regarding objectivity--and the methodological limitations found in too many studies on this topic.