stimulants

stimulants A stimulant is a rather imprecise term used for a variety of different kinds of drug, some with medical uses and others with only recreational use. Psychomotor stimulants produce locomotor activity (the subject becomes hyperactive), euphoria, (often expressed by excessive talking and garrulous behaviour), and anorexia. The amphetamines are the best known drugs in this category, the actions in the central nervous system depending on the release of noradrenaline, dopamine, and possibly 5HT. Many tests show that the amphetamines reduce physical and mental fatigue, but the accuracy of mental deliberations is likely to be reduced also. Nevertheless, the amphetamines once enjoyed a reputation among students for improving performance at examinations. Excessive use leads to insomnia and repeated use leads to a level of dependence. Amphetamines also have actions outside the nervous system, causing hypertension.

cocaine is also a psychomotor stimulant and users are typically extroverted, party-loving individuals. Cocaine blocks the re-uptake of noradrenaline at synapses within the brain and elsewhere, with effects similar to the amphetamines. Cocaine is produced by bushy plants growing in Bolivia and Peru, and hardworking peasants chew the leaves to reduce the fatigue they feel from their toiling, but also to reduce hunger. The dependence which develops with cocaine presents a serious problem in the developed world.

caffeine and theophylline, both methylxanthines, found in tea, coffee, and some soft drinks, are mild psychomotor stimulants. They reduce mental and physical fatigue, without affecting locomotor activity or producing euphoria. It is doubtful whether caffeine and theophylline can produce true dependence. Methylxanthines have some other actions, causing increased urine production and stimulation of heart muscle.

Drugs of another type are used as respiratory stimulants in deeply comatose patients or those with respiratory failure. These are more properly described as analeptics (meaning restorative); nikethamide is an example. Some purgatives, such as cascara and senna, are described as stimulant purgatives and work in the gut, releasing substances which cause peristaltic movements and lead to a temporary diarrhoea.

Alan W. Cuthbert