Cocaine blocks reabsorption of a neurotransmitter called dopamine by nerve cells, or neurons, in one of the brain's key pleasure centers. The resulting buildup of dopamine in the space between nerve cells causes continuous stimulation of receiving neurons. Scientists believe this action plays a major role in the euphoria reported by cocaine abusers. Cocaine's effects appear almost immediately and disappear in a few minutes or hours, depending on the route of administration. Injected and smoked cocaine produces intense effects rapidly.
Small amounts make the user feel euphoric, energetic, talkative, and alert.
Large amounts intensify these feelings but may lead to bizarre, erratic, and violent behavior. Physiological effects include constricted blood vessels, dilated pupils, and increased temperature, heart rate, and blood pressure. Some users report feelings of restlessness, irritability, and anxiety. In rare instances, sudden death can occur, usually from cardiac arrest followed by respiratory arrest. Cardiovascular effects include disturb-ances in heart rhythm and heart attacks.