Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. It is a stimulant of the central nervous system and an appetite suppressant, creating what has been described as a euphoric sense of happiness and increased energy. Though most often used recreationally for this effect, cocaine is also a topical anesthetic used in eye, throat, and nose surgery. Cocaine can be psychologically addictive, and its possession, cultivation, and distribution is illegal for non-medicinal and non-government sanctioned purposes in virtually all parts of the world. The name comes from the name of the coca plant plus the alkaloid suffix -ine.
The stimulating qualities of the coca leaf were known to the ancient peoples of Peru and other Pre-Columbian South American societies. In modern Western countries, cocaine has been a feature of the counterculture for well-over a century; there is a long-list of prominent intellectuals, artists, and musicians who have used the drug -- names ranging from Sir Arthur Conan Doyle and Sigmund Freud to United States President Ulysses S. Grant. For many decades cocaine was a key ingredient in Coca-Cola. Today, although illegal in virtually all countries, cocaine remains popular in a wide variety of social and personal settings.
Effects and health issues
Cocaine is a potent central nervous system stimulant. Its effects can last from 20 minutes to several hours, depending upon the dosage of cocaine taken, purity, and method of administration.
The initial signs of stimulation are hyperactivity, restlessness, increased blood pressure, increased heart rate and euphoria. The euphoria is sometimes followed by feelings of discomfort and depression and a craving to experience the drug again. Sexual interest and pleasure can be amplified. Side effects can include twitching, paranoia, and impotence, which usually increases with frequent usage.
With excessive dosage the drug can produce hallucinations, paranoid delusions, tachycardia, itching, and formication.
Overdose causes tachyarrhythmias and a marked elevation of blood pressure. These can be life-threatening, especially if the user has existing cardiac problems.
The LD50 of cocaine when administered to mice is 95.1 mg/kg.  Toxicity results in seizures, followed by respiratory and circulatory depression of medullar origin. This may lead to death from respiratory failure, stroke, cerebral hemorrhage, or heart-failure. Cocaine is also highly pyrogenic, because the stimulation and increased muscular activity cause greater heat production. Heat loss is inhibited by the intense vasoconstriction. Cocaine-induced hyperthermia may cause muscle cell destruction and myoglobinuria resulting in renal failure. There is no specific antidote for cocaine overdose.
Cocaine's primary acute effect on brain chemistry is to raise the amount of dopamine and serotonin in the nucleus accumbens (the pleasure center in the brain); this effect ceases, due to metabolism of cocaine to inactive compounds and particularly due to the depletion of the transmitter resources (tachyphylaxis). This can be experienced acutely as feelings of depression, as a "crash" after the initial high. Further mechanisms occur in chronic cocaine use.
With chronic cocaine intake, brain cells functionally adapt (respond) to strong imbalances of transmitter levels in order to compensate extremes. So receptors disappear from or reappear on the cell surface, resulting more or less in an "off" or "working mode" respectively, or they change their susceptibility for binding partners (ligands) – mechanisms called down-/upregulation. Chronic cocaine use leads to a DAT upregulation, further contributing to depressed mood states. Finally, a loss of vesicular monoamine transporters appears to indicate a long term damage of dopamine neurons.
All these effects contribute to the rise in an abuser's tolerance thus requiring a larger dosage to achieve the same effect. The lack of normal amounts of serotonin and dopamine in the brain is the cause of the dysphoria and depression felt after the initial high. The diagnostic criteria for cocaine withdrawal is characterized by a dysphoric mood, fatigue, unpleasant dreams, insomnia or hypersomnia, E.D., increased appetite, psychomotor retardation or agitation, and anxiety.
Cocaine abuse also has multiple physical health consequences. It is associated with a lifetime risk of heart attack that is seven times that of non-users. During the hour after cocaine is used, heart attack risk rises 24-fold.
Side effects from chronic smoking of cocaine include chest pain, lung trauma, shortness of breath, sore throat, hoarse voice, dyspnea, and an aching, flu-like syndrome. A common misconception is that the smoking of cocaine breaks down tooth enamel and causes tooth decay. In addition, cocaine often causes involuntary tooth grinding, known as bruxism, which can deteriorate tooth enamel and lead to gingivitis.
Chronic intranasal usage can degrade the cartilage separating the nostrils (the septum nasi), leading eventually to its complete disappearance. Due to the absorption of the cocaine from cocaine hydrochloride, the remaining hydrochloride forms a dilute hydrochloric acid.
Cocaine may also greatly increase this risk of developing rare autoimmune or connective tissue diseases such as lupus, Goodpasture's disease, vasculitis, glomerulonephritis and other diseases. . It can also cause a wide array of kidney diseases and renal failure . While these conditions are normally found in chronic use they can also be caused by short term exposure in susceptible individuals.
There have been published studies reporting that cocaine causes changes in the frontal lobe of the brain. The full extent of possible brain deterioration from cocaine use is not known.