Cocaine and It Effects

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

Ð"Ñšber 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 systems probably

are involved, directly or indirectly, in mediating CNS toxicity. With regular use, moreover, neuroadaptive mechanisms

result in development of tolerance, reverse tolerance, and dependence.

Frequency:

In the US: Cocaine use in the United States has reached epidemic proportions. In the second half of the last century,

cocaine consumption in North America rose rapidly; by the late 1980s, 30 million people were cocaine users and 6

million were cocaine addicts. In the United States, 5 million people take cocaine regularly, and every day approximately

5000 people try cocaine for the first time. Estimates in the 1990s suggested that 30-40 million Americans have some

experience with cocaine and that 1 of every 2 persons aged 25-30 years has used the drug. The incidence of neurological

complications is not known.

Internationally: The figures for the consumption of cocaine have risen progressively in all Central American countries,

Europe,