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Psychostimulants

Psychostimulantia

For medical students2 min readUpdated 2026-10-10

Psychostimulants are pharmacological agents that stimulate brain functions, primarily the cerebral cortex, by facilitating interneuronal transmission. They produce a marked increase in mental and motor activity, enhance performance, and reduce the need for sleep.

LocalizationCerebral cortex, activation of interneuronal transmission

ClassesPhenylalkylamines, sydnonimines, methylxanthines

TargetsNorepinephrine and dopamine in synapses

ActionIncreased activity, fatigue reduction, anorexigenic effect

General Characteristics and Pharmacological Effects

The pharmacological group of psychostimulants unites compounds that affect the central nervous system. Their primary action consists of stimulating brain functions and facilitating interneuronal transmission.

Key clinical and physiological effects of administration:

Enhanced mental performance and concentration.
Increased reflex speed and physical endurance.
Reduced sensation of fatigue and decreased need for sleep.
Suppressed appetite (anorexigenic effect).

An important property of these substances is dose-dependency: at high doses, they can exhibit analeptic (arousing) effects, but this also provokes anxiety, nervousness, and physical tension.

Classification of Psychostimulants

Drug grouping is based on their chemical structure and mechanism of action. Modern pharmacology distinguishes three main groups:

Phenylalkylamine derivatives — a prominent representative is amphetamine. The drug is a racemic mixture of isomers, with the dextrorotatory isomer carrying the main activity.
Sydnonimine derivatives — these include mesocarb (sydnocarb).
Methylxanthine derivatives — the classic example is caffeine.

Mechanism of Action and CNS Effects

The neurochemical action of phenylalkylamine derivatives is linked to their effects on catecholamines. These drugs trigger the active release of norepinephrine and dopamine from presynaptic terminals, block their neuronal reuptake, and also exhibit inhibitory activity against monoamine oxidase (MAO).

At the organism level, this manifests as central and peripheral effects:

Psychostimulatory action: euphoria, elimination of fatigue, increased performance. Notably, high work speed may be accompanied by reduced accuracy.
Autonomic manifestations: elevated blood pressure, tachycardia, and increased myocardial oxygen demand due to adrenoceptor stimulation.
Age-related features: adults experience psychostimulation, whereas children may exhibit a sedative (calming) effect from the same drugs.

Energy Balance and Body Adaptations

The use of psychostimulants is accompanied by a major mobilization of internal resources. Regular intake leads to rapid depletion of the body's energy reserves because these agents consume existing reserves rather than generating new energy. Furthermore, continuous stimulation of the feeding center in the hypothalamus leads to a persistent reduction in food intake.

Mnemonic

Psychostimulants boost tone and speed up reflexes, but remember the rule: they burn energy at the expense of the body's internal resources.

Frequently asked questions

Which drugs belong to the methylxanthine derivative group?

The methylxanthine group includes caffeine, theobromine, theophylline, and aminophylline.

Caffeine — an alkaloid with the most pronounced effect on the CNS; blocks purine receptors and inhibits phosphodiesterase.
Theobromine — a plant-derived alkaloid.
Theophylline — an alkaloid that blocks purine receptors.
Aminophylline — a drug with choleespasmolytic effects (reduces smooth muscle tone in the biliary tract).

What adverse effects are characteristic of high-dose or chronic psychostimulant use?

High doses and chronic use can cause anxiety, nervousness, physical tension, psychotic disorders, fatigue, exhaustion of the body's energy reserves, insomnia, and dependence.

High doses: anxiety, nervousness, physical tension. Overdose may cause tremor and convergence insufficiency. Higher doses can lead to hallucinatory-delusional psychosis, including persecutory delusions, auditory, and tactile hallucinations.
Chronic use: rapid fatigue, depletion of energy reserves, insomnia, tolerance, and a high risk of drug addiction. For caffeine, literature notes the possibility of tolerance and substance dependence (thetism).

What are the main medical indications for prescribing psychostimulants?

Main indications include conditions characterized by reduced activity and specific syndromes:

Psychiatry and neurology: mild negative, depressive, and apathico-abulic disorders in schizophrenia, subdepressive states.
Asthenia: generalized weakness and asthenic states.
Sleep disorders: hypersomnia (narcolepsy).
Pediatrics: attention deficit hyperactivity disorder (ADHD).
Therapy adjustment: countering adverse effects of sedatives and anticonvulsants.
Other: obesity (occasionally, due to the anorexigenic effect).

What are the contraindications for psychostimulant use?

For caffeine, specific contraindications include:

severe arterial hypertension;
atherosclerosis;
glaucoma;
insomnia.

How do the mechanism of action and spectrum of effects of mesocarb (sydnocarb) differ from amphetamine?

Mesocarb differs from amphetamine by having a milder action, lacking initial euphoria, and having less impact on autonomic functions.

Characteristic	Mesocarb (Sydnocarb)	Amphetamine
Mechanism of action	Displaces norepinephrine from presynaptic vesicles into the synaptic cleft, activating noradrenergic transmission	Causes release of catecholamines from presynaptic terminals; blocks neuronal reuptake of norepinephrine and dopamine, and inhibits MAO
Onse of effect	Gradual, "mild", without initial euphoria	Characterized by psychostimulatory action and development of euphoria
Energy balance	Does not cause subsequent depletion of the body's energy reserves	Regular intake leads to rapid depletion of energy resources
Autonomic effects	Peripheral sympathomimetic action is negligible; provokes blood pressure spikes to a lesser degree	Elevates blood pressure and causes tachycardia
Dependence	Develops significantly slower than with phenylalkylamine derivatives	High risk of pathological craving and dependence

What are the main neurotransmitter targets for amphetamine?

The primary neurotransmitter targets are norepinephrine and dopamine. The drug stimulates their release from presynaptic terminals and blocks their reuptake.

What are the age-related differences in the action of psychostimulants?

In adults, these substances cause a pronounced psychostimulatory effect, whereas children exhibit a paradoxical sedative (calming) effect.

How do psychostimulants affect the cardiovascular system?

They cause elevated blood pressure, tachycardia, and increase myocardial oxygen demand due to enhanced norepinephrine release and adrenoceptor stimulation.

Go deeper

Pharmacology of sydnonimine derivatives (mesocarb)
Specifics of methylxanthine derivatives (caffeine)
Effects of amphetamine on the hypothalamus and feeding center
Tolerance development and energy depletion during psychostimulant use
Comparative analysis of central and peripheral effects of sympathomimetics