to Wootton Report Index
Cannabis is the generic name for Indian Hemp (C. sativa). Cannabis drugs are obtainable
from the flowing tops or leaves of the plant. The resin of C. sativa is often
referred to as hashish and its constituents include cannabidiol, cannabinol and
several tetrahydrocannabinols referred to collectively as T.H.C. Other constituents
are cannabigerol, cannabichromene and cannabidiolic acid. The active principles
are T.H.C., two of them. D l and D 6 T.H.C., being of great potency. The relations
between the constituents and the possibilities of interconversion between some
of them under different conditions such as the high temperature and degree of
oxygenation that occur during smoking have been studied but are not as yet fully
elucidated. Work is hindered by the relative insolubility of these substances.
The relative and total amounts of the active principles in a sample of
cannabis depend upon climatic factors during growth, processing or preparation
and the form in which the drug is used. For example, D 6 T.H.C. is approximately
2-5 times as active when smoked as it is when swallowed. The rate and degree of
absorption and hence the onset and duration of effect are related to the route
of administration (inhalation being faster than oral administration) and the expertise
of the smoker in prolonging contact between the smoke and the absorptive surfaces
of the lung, etc. In man inhaled smoke initiates effects within a few minutes
and a maximal effect may be obtained after a half to one hour. By inhalation a
certain degree of control is attained according to the effect desired. The action
persists for some 3-5 hours.
Chemical methods of analysing the constituents and products of hashish include
chromatographv and spectrophotometry. Quantitative isolation of the active principles
or their metabolites from body fluids is at present not possible and consistent
recoveries cannot yet be guaranteed. There is no precise knowledge about absorption,
distribution, mode of action or metabolic degradation of the T.H.C. or the other
constituents of cannabis in man.
In animals gross overdosage with cannabis causes death from respiratory depression.
Cannabis prolongs the sleeping time of mice treated with hypnotic doses of barbiturates
and this effect is said to persist over a period of 2-3 months. Such a prelonged
effect suggests that cannabis has interfered with adaptive lysosomal enzyme systems.
Cannabis also intensifies the stimulant effect of amphetamine in mice as judged
by the degree of restlessness produced, another effect which may be due to inhibition
of hepatic enzymic activity. Whether these two important interactions occur in
man is not known. Pharmacological research on man is at present severely limited
by the existing drug laws and regulations.