LSD, MESCALINE, & PSILOCYBIN
mescaline, and psilocybin are commonly called hallucino-gens because of their
ability to alter consciousness such that the individual senses things that are
not present. They induce, often in an unpredictable way, perceptual symptoms,
including shape and color distortion. Psychosis-like manifestations
(depersonaliza-tion, hallucinations, distorted time perception) have led some
to classify these drugs as psychotomimetics. They also produce somatic symptoms
(dizziness, nausea, paresthesias, and blurred vision). Some users have reported
intense reexperiencing of per-ceptual effects (flashbacks) up to several years
after the last drug exposure.Hallucinogens differ from most other drugs
described in that they induce neither dependence nor addiction. However,
repetitive exposure still leads to rapid tolerance (also called tachyphylaxis).
Animals do not self-administer hallucino-gens, suggesting that they are not
rewarding to them. Additional studies show that these drugs also fail to
stimulate dopamine release, further supporting the idea that only drugs that
activate the mesolimbic dopamine system are addictive. Instead, halluci-nogens
increase glutamate release in the cortex, presumably by enhancing excitatory
afferent input via presynaptic serotonin receptors (eg, 5HT2A)
from the thalamus.
LSD is an ergot alkaloid.
After synthesis, blotter paper or sugar cubes are sprinkled with the liquid and
allowed to dry. When LSD is swallowed, psychoactive effects typically appear
after 30 minutes and last 6–12 hours. During this time, subjects have impaired
ability to make rational judgments and understand common dan-gers, which puts
them at risk for accidents and personal injury.
In an adult, a typical
dose is 20–30 mcg. LSD is considered neurotoxic and like most ergot alkaloids,
may lead to strong con-tractions of the uterus that can induce abortion .The
main molecular target of LSD and other hallucinogens is the 5-HT2A
receptor. This receptor couples to G proteins of the Gq type and
generates inositol trisphosphate (IP3), leading to a release of
intracellular calcium. Although hallucinogens, and LSD in particular, have been
proposed for several therapeutic indica-tions, efficacy has never been