Chapter 6: Stimulants
Stimulants can reverse the effects of fatigue, maintain wakefulness, decrease appetite, and temporarily elevate the mood of the user. Cocaine and amphetamine are restricted stimulants, while nicotine and caffeine are readily available.
Cocaine is derived from the coca plant, which grows in the Andes mountains. Natives have a long history of chewing coca leaves to increase endurance and strength. Coca leaf extract was introduced to the general public when it was used in products such as wine and patent medicines. Once isolated from coca leaves, cocaine was used medically as a local anesthetic. Sigmund Freud promoted its use for the treatment of depression and morphine dependence until he became aware of its serious effects. Cocaine hydrochloride can be snorted or injected; coca paste, crack, and freebase cocaine can be smoked or inhaled.
In the U.S., individual states and then the federal government passed laws to regulate the importation and sale of cocaine, first in 1914 and then in the 1980s. The Anti-Drug Abuse Acts of 1986 and 1988 made penalties for the sale and use of crack cocaine significantly more severe than the penalties associated with powder cocaine, and concerns have been raised about whether these penalties are appropriate and whether they disproportionately affect the black community.
Cocaine acts on the brain by blocking the reuptake of several neurotransmitters. The onset of effects is generally fairly rapid, and the cocaine molecules are then metabolized by enzymes in the blood and liver. Synthesized drugs have largely replaced cocaine for medical use, but cocaine remains in use for surgery in the nasal, laryngeal, and esophageal regions.
Acute cocaine toxicity can lead to respiratory or cardiac arrest, paranoid psychosis, and even death. The use of cocaine during pregnancy increases the risk of miscarriage and may have long-term effects in infants. Cocaine is a powerfully reinforcing drug and its use can cause to dependence and withdrawal symptoms. Usage rates of cocaine tend to cycle in opposition to the usage rates of amphetamine.
The Chinese used a medical tea made from ma huang. Amphetamines are a synthetic sympathomimetic similar to ephedrine, the active ingredient in ma huang. Amphetamines increase the activity of dopamine, norepinephrine, and serotonin by stimulating their release. Peak effects occur most rapidly following intravenous injection or smoking; absorption is slower following intranasal administration or oral ingestion. High doses of amphetamine lead rapidly to tolerance.
Amphetamines had several early medical uses and were used by soldiers in World War II to fight fatigue. In the 1960s, the recreational use of prescription amphetamines increased, and the drugs became more tightly controlled. In response, many look-alike drugs appeared and some users switched back to cocaine. Illicit manufacture of methamphetamine also grew; the process is dangerous and associated with toxic fumes. Methamphetamine hydrochloride crystals, known as ice or crystal meth, can be smoked.
Amphetamines are used in short-term weight reduction and in treatment of narcolepsy and attention-deficit hyperactivity disorder. Stimulants have also been shown to improve mental performance in people who are tired or fatigued; overstimulation, however, will decrease performance, especially on complex tasks.
Amphetamines can cause acute and chronic toxicity characterized by paranoia, aggression, psychosis, and compulsive and repetitive stereotyped actions. Although there are often no obvious withdrawal symptoms, amphetamines are a potent reinforcer and do produce dependence.