Caffeine - Indications, Dosage, Side Effects and Precautions

USDailyMed:Caffeine AU:A N06BC01(WHO)D11AX26(WHO),V04CG30(WHO) AU:UnscheduledBR:UnscheduledCA: UnscheduledDE: UnscheduledNZ: UnscheduledUK:General sales list(GSL, OTC)US:UnscheduledUN:UnscheduledCN:OTC 1,3,7-Trimethyl-3,7-dihydro-1H-purine-2,6-dione 58-08-2 2519 407 DB00201 2424 3G6A5W338E D00528 CHEBI:27732 ChEMBL113 none CFF (PDBe,RCSB PDB) DTXSID0020232 Interactive image CN1C=NC2=C1C(=O)N(C(=O)N2C)C InChI=1S/C8H10N4O2/c1-10-4-9-6-5(10)7(13)12(3)8(14)11(6)2/h4H,1-3H3Key:RYYVLZVUVIJVGH-UHFFFAOYSA-N Caffeineis acentral nervous system(CNS)stimulantof themethylxanthineclassand is the most commonly consumedpsychoactivesubstance globally.It is mainly used for itseugeroic(wakefulnesspromoting),ergogenic(physical performance-enhancing), ornootropic(cognitive-enhancing) properties; it is alsoused recreationallyor insocialsettings.Caffeine acts by blocking the binding ofadenosineat a number ofadenosine receptortypes, inhibiting the centrallydepressanteffects of adenosine and enhancing the release ofacetylcholine.Caffeine has a three-dimensional structure similar to that of adenosine, which allows it to bind and block its receptors.Caffeine also increasescyclic AMPlevels through nonselectiveinhibition of phosphodiesterase, increases calcium release from intracellular stores, andantagonizesGABA receptors, although these mechanisms typically occur at concentrations beyond usual human consumption. Caffeine is a bitter, white crystallinepurine, a methylxanthinealkaloid, and is chemically related to theadenineandguaninebasesofdeoxyribonucleic acid(DNA) andribonucleic acid(RNA).‍​‍‍‍​‍‍‍‍‍‍‍‍​‍ It is found in the seeds, fruits, nuts, or leaves of a number of plants native toAfrica,East Asia, andSouth Americaand helps to protect them against herbivores and from competition by preventing the germination of nearby seeds,as well as encouraging consumption by select animals such ashoney bees.The most common sources of caffeine for human consumption are thetealeaves of theCamellia sinensisplant and thecoffee bean, the seed of theCoffeaplant. Some people drinkbeveragescontaining caffeine to relieve or prevent drowsiness and to improve cognitive performance. To make these drinks, caffeine is extracted bysteepingthe plant product in water, a process calledinfusion. Caffeine-containing drinks, such as tea,coffee, andcola, are consumed globally in high volumes. In 2020, almost 10 million tonnes of coffee beans were consumed globally.Caffeine is the world's most widely consumedpsychoactive drug.Unlike most other psychoactive substances, caffeine remains largely unregulated and legal in nearly all parts of the world.Caffeine is seen as socially acceptable in most cultures and is encouraged in some.[vague] Caffeine has both positive and negativehealth effects. It can treat and prevent the premature infant breathing disordersbronchopulmonary dysplasiaof prematurity andapnea of prematurity.Caffeine citrateis on theWHO Model List of Essential Medicines.It may confer a modest protective effect against some diseases,includingParkinson's disease.Caffeine can acutely improvereaction timeand accuracy for cognitive tasks.Some people experiencesleep disruptionor anxiety if they consume caffeine,but others show little disturbance. Evidence of a risk during pregnancy is equivocal; some authorities recommend that pregnant women limit caffeine to the equivalent of two cups of coffee per day or less.Caffeine can produce a mild form ofdrug dependence– associated withwithdrawal symptomssuch as sleepiness, headache, and irritability – when an individual stops using caffeine after repeated daily intake.Tolerancedevelops to autonomic effects (blood pressure, heart rate, nervousness) and to alerting/vigilance benefits with regular use. Chronic exposure upregulates adenosine receptors, raising the effort threshold for allocating attention—even to mundane or previously enjoyable tasks—because habitual users operate from a lowered arousal baseline. Caffeine is classified by the USFood and Drug Administration(FDA) asgenerally recognized as safe. Lethal doses, over 10 grams per day for an adult, greatly exceed the typical dose of under 500 milligrams per day.TheEuropean Food Safety Authorityreported that up to 400 mg of caffeine per day (around 5.7 mg/kg of body mass per day) does not raise safety concerns for non-pregnant adults, while intakes up to 200 mg per day for pregnant and lactating women do not raise safety concerns for the fetus or the breast-fed infants.A 6 ounce cup of coffee typically contains 50–175 mg of caffeine, depending on what "bean" (seed) is used (and how much), how it is roasted, and how it is prepared (e.g.,drip,percolation, orespresso).Thus roughly 50–100 ordinary cups of coffee would be required to reach a lethal dose. However, pure powdered caffeine, which is available as adietary supplement, can be lethal in tablespoon-sized amounts.