The world is facing an epidemic of cocaine use by adolescents and young adults from all socioeconomic backgrounds.
Epidemiologic data suggest that cocaine use is a serious public health problem because it is highly addictive and is
associated with a variety of neurological complications.
Cocaine, a natural alkaloid, is extracted from leaves of an Andean shrub, Erythroxylon coca. Coca leaves were used by
the native populations to alleviate the rigors of high altitude and to diminish fatigue. Although cocaine was extracted in
pure form from coca in 1860, Europeans became aware of its potential medical complications only after Sigmund Freud's
Über Coca was published in 1884. It was described by Freud as a wonder drug that could cure depressed mood and
alcohol dependence. It is used as an ophthalmic and spinal anesthetic. An important factor in the most recent epidemic of cocaine use was the popularization in the late 1980s of the smoked
form, known as crack or rock. It was called crack supposedly because of the sound made by crystals of cocaine
popping when heated or rock because of its appearance.
Cocaine remains the primary nonalcoholic drug of abuse. It has been sold on the streets for many years as a
water-soluble hydrochloride (HCl) salt for nasal insufflation (snorting) or intravenous injection. It may be injected
subcutaneously or intramuscularly, but this route rarely is used because vasoconstriction slows absorption and the drug
thus is less likely to result in a "rush."
Cocaine can be smoked only when it is altered to form cocaine base . Smoking of the base results in an almost
instantaneous high due to rapid absorption through the large pulmonary surface area and swift penetration into the brain.
Smoking of cocaine base has increased in many cities throughout the world. Although the nasal route and smoking of the
base currently are in vogue, cocaine can be absorbed readily from any mucous membrane. Irrespective of route of
administration, it causes neurological complications.
Pathophysiology: The most important pharmacological actions of cocaine are blocking the initiation or conduction of the
action potential following local application to a nerve and stimulating the CNS. The local anesthetic effect of cocaine is due to a direct membrane effect. Cocaine blocks the initiation and conduction of
electrical impulses within nerve cells by preventing the rapid increase in cell-membrane permeability to sodium ions during
depolarization. Its systemic effects on the nervous system probably are mediated by alterations in synaptic transmissions.
The most noticeable systemic activity of cocaine is stimulation of the CNS by altering the uptake and metabolism of
norepinephrine, dopamine, serotonin, and acetylcholine.
By blocking presynaptic reuptake of the neurotransmitters norepinephrine and dopamine, cocaine increases the quantity
of neurotransmitters at the postsynaptic receptor sites. The resultant activation of the sympathetic nervous system
produces an acute rise in arterial pressure, tachycardia, and a predisposition to ventricular arrhythmias and seizures.
Sympathetic activation also may result in mydriasis, hyperglycemia, and hyperthermia. The effects of cocaine on
dopaminergic neuronal systems may be involved in producing euphoria and addiction. In the short term, cocaine appears to stimulate dopaminergic neurotransmission by blocking the reuptake of dopamine.
However, evidence suggests that, with long-term use, the nerve terminals may be depleted of dopamine. Dopamine
depletion has been theorized to contribute to the dysphoria that develops during withdrawal from cocaine and the
subsequent craving for more of the drug. In this way, alterations in dopamine neurotransmission may be responsible for
the development of compulsive use patterns. With higher doses and regular use, other neurotransmitter...
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