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 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

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 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, mechanisms called down-upregulation. Chronic cocaine use leads to a upregulation, further contributing to depressed mood states. 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. 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.

Formal Chemical Name (IUPAC)
(1R,5S)-methyl 8-methyl-3-(phenylcarbonyloxy)-8-azabicyclo[3.2.1]octane-2-carboxylate

References

http://en.wikipedia.org/wiki/Cocaine