Stimulans

Stimulans, or stimulant, refers to a substance that increases activity of the central nervous system or autonomic nervous system, producing heightened alertness, attention, energy, and wakefulness. In pharmacology, stimulants (psychostimulants) are used to treat conditions such as attention-deficit/hyperactivity disorder (ADHD) and narcolepsy, and are sometimes employed for appetite suppression or cognitive enhancement, though non-medical use may carry risks of harm and dependency.

Most stimulants raise extracellular levels of dopamine and norepinephrine in the brain by promoting release, inhibiting reuptake, or both. Caffeine acts chiefly as an adenosine receptor antagonist, increasing neuronal firing. Nicotine stimulates nicotinic acetylcholine receptors. Amphetamines and methylphenidate increase monoamines in synapses; modafinil has a distinct but related mechanism. Other stimulants include cocaine, ephedrine, and various botanical or synthetic compounds. Some are widely available, such as caffeine-containing beverages, while others are prescription drugs or controlled substances.

Medical uses include treatment of ADHD and narcolepsy; some agents have historical or limited use for obesity or fatigue. Side effects can include insomnia, anxiety, tachycardia, hypertension, appetite suppression, and potential for dependence or withdrawal upon discontinuation. Safety profiles and regulatory status vary by country, with many stimulants subject to controlled-substance regulations to curb misuse.

Historically, humans have used stimulant substances for centuries, from coffee and tea to nicotine and coca-derived products, with modern pharmaceutical development beginning in the 20th century.