Amphetamine, prototype of a series of synthetic drugs, all called amphetamines, that have pronounced stimulatory actions on the central nervous system. Amphetamine itself is a colourless liquid with an acrid taste and a faint odour; the most widely used preparation of the drug is amphetamine sulfate, marketed under the name Benzedrine, a white powder with a slightly bitter, numbing taste. Dextroamphetamine sulfate, marketed under the name Dexedrine, is the more active of the two optically isomeric forms in which amphetamine exists. Other members of the amphetamine series include methamphetamine and benzphetamine.
These drugs partially reverse the depressant effects of anesthetics, narcotics, hypnotics, and alcohol. All amphetamines cause profound psychic effects, including wakefulness, mental alertness, increased initiative and confidence, euphoria, lessened sense of fatigue, talkativeness, and increased ability to concentrate.
Amphetamine effectively dulls the appetite when taken before meals, so it is widely used as an adjunct to dietary restriction in weight reduction. It is used (sometimes illicitly) by pilots, truckers, and soldiers on long-term missions where prolonged wakefulness is required. The amphetamines have had a major role in the management of hyperactive children because the drugs calm such children and enable them to concentrate, usually within a day after treatment is begun. Amphetamines have also been used in the treatment of narcolepsy.
Amphetamines can produce undesirable effects, the most common of which is overstimulation, with restlessness, insomnia, tremor, tenseness, and irritability. Physical tolerance to amphetamines develops rapidly, so that progressively larger doses must be consumed by the chronic user. The letdown effect that occurs in such users after the drug has worn off consists of a deep mental depression. The most severe aftereffect of large doses of amphetamines is a toxic psychosis whose symptoms resemble those of paranoid schizophrenia. Amphetamine addiction frequently is associated with similar abuse of barbiturates and alcohol.
Learn More in these related Britannica articles:
sleep: Light and deep sleep…arousal in wakefulness, such as amphetamines and antidepressants, suppress REM sleep. In terms of subjective response, recently awakened sleepers often describe REM sleep as having been deep and NREM sleep as having been light. The subjectively felt depth of REM sleep may reflect the immersion of the sleeper in the…
adrenergic drug: Sympathomimetic agents…as a nasal decongestant, and amphetamines. These substances act mainly through mechanisms that result in the release of catecholamines from their storage areas in nerve terminals. Amphetamine-like drugs also have strong effects on the brain, causing feelings of excitement and euphoria as well as reducing appetite, the latter effect leading…
chemical dependency…diazepam, meprobamate and methaqualone, and amphetamines such as methamphetamine and dextroamphetamine. Characteristics of dependency on these drugs include a strong desire or need to continue taking the drug, a periodic tendency to increase the dosage, and a psychic and physical need to rely on the drug’s effects for the maintenance…