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4. PSYCHOPHARMACOLOGY OF DEPENDENCE FOR DIFFERENT DRUG CLASSES

and is metabolized to another active compound, 11-OH-delta-9-THC.
Cannabinoids are generally inhaled by smoking, but may also be ingested.
Peak intoxication through smoking is reached within 15–30 minutes and the
effects last for 2–6 hours. Cannabinoids remain in the body for long periods
and accumulate after repeated use. Cannabinoids may be found in the urine
for 2–3 days after smoking a single cigarette and for up to 6 weeks after the
last use in heavy users.
Several studies (e.g. Tramer et al. 2001) have demonstrated therapeutic
effects of cannabinoids, e.g. in controlling nausea and vomiting in some cancer
and AIDS patients. This has led to controversial discussion regarding the
potential beneficial effects of cannabis itself in certain conditions (see Box 4.4).

Behavioural effects

The perception of time is slowed and there are feelings of relaxation and of
sharpened sensory awareness. The perception of increased self-confidence
and heightened creativity is not accompanied by better performance and
there is impairment of short-term memory and of motor coordination.
Analgesia, antiemetic and antiepileptic action, and increased appetite are

BOX 4.4

Therapeutic potential for cannabis
Therapeutic uses of D-9-tetrahydrocannabinol (THC) have led to discussions about
the therapeutic potential of cannabis itself, although little research exists in this
area and satisfactory clinical studies have not been conducted. In order to explore
possible therapeutic uses of cannabis, several scientific issues need to be
considered, including:
— the standardization of cannabis preparations required for some types of clinical
and preclinical studies
— the difficulties inherent in the study of smoking as the mode of administration
of a substance
— the need for a comparable placebo “cigarette” which would not be easily
identified by experimental subjects and patients in controlled trials.
— the large number of patients which would be needed to study the comparative
efficacy of smoking cannabis compared with other cannabinoids and other
therapeutic agents.
—the possibility of using alternative delivery systems which could avoid smoking
cannabis as well as the other components contained in its smokable form.In
addition, the broader implications of such research on cannabis control policies
would need to be carefully considered.
Source: WHO, 1997a.

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