nikotín

Nikotín, also known as nicotine, is an alkaloid found in tobacco plants and other members of the Solanaceae family, most notably Nicotiana tabacum. It is the principal addictive component of tobacco products and occurs in tobacco leaves in varying concentrations. The chemical formula is C10H14N2, and it is a colorless to pale yellow oily liquid that is highly soluble in water.

It acts as an agonist of nicotinic acetylcholine receptors (nAChRs) in the central and peripheral nervous systems. Activation of these receptors leads to the release of neurotransmitters such as dopamine, norepinephrine, acetylcholine and glutamate, producing arousal, improved attention and a feeling of reward. This receptor activity underlies nicotine's reinforcing properties and dependence potential.

Pharmacokinetics: When inhaled (smoked), nicotine is rapidly absorbed through the lungs and reaches the brain within seconds; other routes such as oral, sublingual or transdermal delivery yield slower, more variable absorption. It is mainly metabolized in the liver by cytochrome P450 2A6 to cotinine, which has a longer half-life (about 16 hours). Nicotine and cotinine are excreted in urine.

Uses and regulation: Nicotine is used medically in nicotine replacement therapy to aid smoking cessation, available as gum, patches, lozenges, nasal spray and inhalers. It is also delivered via tobacco products and electronic nicotine delivery systems. Regulatory approaches vary, but most countries restrict sales to adults and impose safety warnings. While nicotine itself is not a major carcinogen, it has cardiovascular effects and may affect tumor biology; the harmful health effects of tobacco mainly arise from other tobacco constituents.

History and naming: Nicotine was first isolated in 1828 by Posselt and Reimann. The name derives from Jean Nicot, the French ambassador who popularized tobacco in France; the genus Nicotiana is named after him.