C

caffeine A CENTRAL NERVOUS SYSTEM stimulant.
Though not commonly perceived as a DRUG of
abuse, caffeine is the most widely used psychoac-
tive drug in the world. The primary sources of caf-
feine are coffee, tea, and colas. Chocolate also
contains some caffeine. A typical cup of coffee
contains 100 to 150 milligrams (mg) of caffeine;
tea and cola drinks contain 60 to75 mg per serv-
ing. Many OVER-THE-COUNTER(OTC) DRUGS, notably
those for PAINrelief and relief of menstrual cramps,
contain caffeine. Chocolate may contain 3 to 5 mg
of caffeine per ounce. Though researchers disagree
as to whether caffeine is addictive, many people
experience mild withdrawal symptoms when
stopping caffeine after long-term consumption of
caffeinated beverages. Such symptoms may
include HEADACHE, irritability, difficulty concentrat-
ing, and cravings for the beverage. Excessive caf-
feine consumption may cause PALPITATIONS,
agitation, and feelings of anxiety.
See also ANALGESIC MEDICATIONS; DYSMENORRHEA;
NICOTINE; PERFORMANCE-ENHANCING SUBSTANCES; STIM-
ULANTS.

cannabis The plant Cannabis sativa, the source
for marijuana, hashish, and hash oil. Cannabis is
the most widely used illicit DRUGin the Western
world; more than 80 million Americans have used
marijuana, the most common form of cannabis,
at least once and about 15 million use it regu-
larly. The primary psychoactive chemical in
cannabis substances is delta-9-tetrahydrocannabi-
nol, commonly called THC. THC has moderate
risk for DEPENDENCE and ADDICTION. ALCOHOL
potentiates (enhances and alters) the effects of
THC when a person consumes the two drugs
together.

Cannabis sativa is among several species of

Cannabiscultivated in many parts of the world for

hemp, the tough fibers of the plant’s stem, for use

in making rope, floor coverings, nets, and some-

times clothing. Stems and hemp fibers do not con-

tain THC. However, in the United States growth,

cultivation, and possession of Cannabisare illegal

(schedule 1 drug) no matter the reason.

Medical Uses

At present the only accepted medical use of THC is

the synthetic formulation dronabinol (Marinol),

which doctors may prescribe to treat NAUSEAasso-

ciated with CHEMOTHERAPYand to improve APPETITE

in people who have AIDS. Dronabinol is a sched-

ule 3 drug in the United States; possession and use

requires a physician’s prescription.

Considerable research has explored the ability

of THC to decrease INTRAOCULAR PRESSURE(pressure

within the EYE) as a treatment for GLAUCOMA. How-

ever, research results have been inconclusive.

Though THC (in therapeutic use often referred to

as medical marijuana) does lower intraocular

pressure the effect lasts only as long as THC is

active in the body, about five hours. THC’s psy-

choactive effects make the drug impractical for

glaucoma treatment.

Actions and Effects in the Body

THC produces euphoria, heightened or altered

sensory perceptions, and a sensation of calm and

relaxation. It exerts its psychoactive actions by

binding with cannabinoid receptors in the BRAIN.

Ordinarily the NEUROTRANSMITTER anandamide

binds with these receptors, which are abundant in

certain parts of the brain, including the hippocam-

pus, cerebellum, and basal ganglia. The hippocam-

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