kofeiin

Kofeiin, or caffeine, is a natural alkaloid stimulant found in the seeds, leaves, and fruits of several plants, including Coffea species (coffee), Camellia sinensis (tea), Theobroma cacao (cocoa), and Cola nuts. It is widely consumed in beverages and foods and is also used in some medicines as a stimulant or to reduce drowsiness.

Chemically, kofeiin is a xanthine derivative known as 1,3,7-trimethylxanthine. Its molecular formula is C8H10N4O2 and its molecular weight is 194.19 g/mol. In the body, caffeine acts mainly as a non-selective antagonist of adenosine receptors (A1 and A2A), which reduces the inhibitory effects of adenosine and promotes wakefulness. It also increases the release of neurotransmitters such as dopamine and norepinephrine, contributing to improved attention and mood at moderate doses.

Pharmacokinetics and metabolism: caffeine is rapidly absorbed from the gastrointestinal tract, with peak blood levels usually reached within 30 to 60 minutes. It is primarily metabolized in the liver by the enzyme CYP1A2 into metabolites including paraxanthine, theobromine, and theophylline, which contribute to the overall stimulant effect. The elimination half-life varies widely, typically about 3 to 5 hours in healthy adults, but longer in pregnancy and with certain medications or liver conditions.

Uses and safety: caffeine is widely present in coffee, tea, chocolate, and many energy drinks, and is also used in some medications to counteract drowsiness. In moderate doses, it can enhance alertness and cognitive performance; high intake may cause jitters, insomnia, anxiety, rapid heartbeat, or digestive upset. A general guideline for adults is up to about 400 mg per day, with lower limits for pregnant individuals and those sensitive to caffeine. Interactions with certain drugs and smoking can alter caffeine metabolism.