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4. PSYCHOPHARMACOLOGY OF DEPENDENCE FOR DIFFERENT DRUG CLASSES

Fig.4.3 Comparison of dopamine D2 receptor binding in the brains of a
control subject and a person with methamphetamine
dependence

Source: Volkow et al., 2001a. Reproduced with permission from the publisher.

similar to these substances. Ecstasy is classifiable as a hallucinogen, due to
the potential induction of hallucinations if used in extremely high doses
(American Psychiatric Association, 1994; WHO, 2001). As the subjective effects
of MDMA in humans are not the same as those produced by LSD and because
the drug does not present similar structure or pharmacological activity to
hallucinogens, the term “entactogens”, meaning “entering in contact with
yourself ” (Nichols, 1986; Morgan, 2000) was proposed to define a new
pharmacological class. As the understanding of the drug effects increases,
its classification will be more accurate. Use of ecstasy has recently been
associated with the global trend of dance parties (or “raves”) and “techno”
music (WHO, 2001).
Psychostimulant effects of MDMA are observed 20–60 minutes after oral
ingestion of moderate doses (50–125 mg) of ecstasy and last from 2–4 hours
(Grispoon & Bakalar, 1986). Peak plasma levels of ecstasy occur 2 hours after
oral administration, and only residual levels are found 24 hours after the last
dose (Verebey, Alrazi & Jafre, 1988; Cami et al., 1997). MDMA has a non-linear
pharmacokinetic profile: consumption of elevated doses of the substance
may produce disproportional elevation of plasma levels of ecstasy (Cami et
al., 1997; de la Torre et al., 2000).

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