Caffeine

This article is about the stimulant drug. For other uses, see Caffeine (disambiguation).

Caffeine
2D structure of caffeine
Clinical data
Pronunciation/kæˈfiːn, ˈkæfiːn/
Other namesGuaranine
Methyltheobromine
1,3,7-Trimethylxanthine
7-methyltheophylline[1] Theine
AHFS/Drugs.comMonograph
License data
Pregnancy
category
  • AU: A
Dependence
liability		Physical: Moderate 13% and variable low–high 10–73%[2]
Psychological: Low–moderate[2]
Addiction
liability		Relatively low: 9%[3]
Routes of
administration		Common: By mouth Medical: intravenous
Uncommon: insufflation, rectal, transdermal, topical
Drug classStimulant;
Adenosinergic;
Eugeroic;
Nootropic;
Anxiogenic;
Analeptic;
Phosphodiesterase inhibitor;
Diuretic
ATC code
Legal status
Legal status
In general Legal for all uses
Pharmacokinetic data
Bioavailability99%[4]
Protein binding10–36%[5]
MetabolismPrimary: CYP1A2[5]
Minor: CYP2E1,[5] CYP3A4,[5]
CYP2C8,[5] CYP2C9[5]
Metabolites• Paraxanthine 84%
• Theobromine 12%
• Theophylline 4%
Onset of action45 minutes–1 hour[4][6]
Elimination half-lifeAdults: 3–7 hours[5]
Infants (full term): 8 hours[5]
Infants (premature): 100 hours[5]
Duration of action3–4 hours[4]
ExcretionUrine (100%)
Identifiers
  • 1,3,7-Trimethyl-3,7-dihydro-1H-purine-2,6-dione
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
PDB ligand
CompTox Dashboard (EPA)
ECHA InfoCard100.000.329 Edit this at Wikidata
Chemical and physical data
FormulaC8H10N4O2
Molar mass194.194 g·mol−1
3D model (JSmol)
Density1.23 g/cm3
Melting point235 to 238 °C (455 to 460 °F) (anhydrous)[7][8]
  • 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,1-3H3
  • Key:RYYVLZVUVIJVGH-UHFFFAOYSA-N
Data page
Caffeine (data page)

Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class and is the most commonly consumed psychoactive substance globally.[9][10] It is mainly used for its eugeroic (wakefulness promoter), ergogenic (physical performance enhancing), or nootropic (cognition improving) properties.[11][12] Caffeine acts by blocking binding of adenosine at a number of adenosine receptor types, inhibiting the centrally depressant effects of adenosine and enhancing the release of acetylcholine.[13] Caffeine has a three-dimensional structure similar to that of adenosine, which allows it to bind and block its receptors.[14] Caffeine also increases cyclic AMP levels through nonselective inhibition of phosphodiesterase, increases calcium release from intracellular stores, and antagonises GABA receptors, although these mechanisms typically occur at concentrations beyond usual human consumption.[10][15]

Caffeine is a bitter, white crystalline purine, a methylxanthine alkaloid, and is chemically related to the adenine and guanine bases of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is found in the seeds, fruits, nuts, or leaves of a number of plants native to Africa, East Asia and South America[16] and helps to protect them against herbivores and from competition by preventing the germination of nearby seeds,[17] as well as encouraging consumption by select animals such as honey bees.[18] The best-known source of caffeine is the coffee bean, the seed of the Coffea plant. People may drink beverages containing caffeine to relieve or prevent drowsiness and to improve cognitive performance. To make these drinks, caffeine is extracted by steeping the plant product in water, a process called infusion. Caffeine-containing drinks, such as coffee, tea, and cola, are consumed globally in high volumes. In 2020, almost 10 million tonnes of coffee beans were consumed globally.[19] Caffeine is the world's most widely consumed psychoactive drug.[20][21] Unlike most other psychoactive substances, caffeine remains largely unregulated and legal in nearly all parts of the world. Caffeine is also an outlier as its use is seen as socially acceptable in most cultures with it even being encouraged.

Caffeine has both positive and negative health effects. It can treat and prevent the premature infant breathing disorders bronchopulmonary dysplasia of prematurity and apnea of prematurity. Caffeine citrate is on the WHO Model List of Essential Medicines.[22] It may confer a modest protective effect against some diseases,[23] including Parkinson's disease.[24] Some people experience sleep disruption or anxiety if they consume caffeine,[25] 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.[26][27] Caffeine can produce a mild form of drug dependence – associated with withdrawal symptoms such as sleepiness, headache, and irritability – when an individual stops using caffeine after repeated daily intake.[28][29][2] Tolerance to the autonomic effects of increased blood pressure and heart rate, and increased urine output, develops with chronic use (i.e., these symptoms become less pronounced or do not occur following consistent use).[30]

Caffeine is classified by the U.S. Food and Drug Administration (FDA) as generally recognized as safe. Toxic doses, over 10 grams per day for an adult, are much higher than the typical dose of under 500 milligrams per day.[31] The European Food Safety Authority reported 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.[32] A cup of coffee contains 80–175 mg of caffeine, depending on what "bean" (seed) is used, how it is roasted, and how it is prepared (e.g., drip, percolation, or espresso).[33] Thus it requires roughly 50–100 ordinary cups of coffee to reach the toxic dose. However, pure powdered caffeine, which is available as a dietary supplement, can be lethal in tablespoon-sized amounts.

  1. ^ "Caffeine". ChemSpider. Archived from the original on 14 May 2019. Retrieved 16 November 2021.
  2. ^ a b c Juliano LM, Griffiths RR (October 2004). "A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features". Psychopharmacology. 176 (1): 1–29. doi:10.1007/s00213-004-2000-x. PMID 15448977. S2CID 5572188. Results: Of 49 symptom categories identified, the following 10 fulfilled validity criteria: headache, fatigue, decreased energy/ activeness, decreased alertness, drowsiness, decreased contentedness, depressed mood, difficulty concentrating, irritability, and foggy/not clearheaded. In addition, flu-like symptoms, nausea/vomiting, and muscle pain/stiffness were judged likely to represent valid symptom categories. In experimental studies, the incidence of headache was 50% and the incidence of clinically significant distress or functional impairment was 13%. Typically, onset of symptoms occurred 12–24 h after abstinence, with peak intensity at 20–51 h, and for a duration of 2–9 days.
  3. ^ Cite error: The named reference pmid24761279 was invoked but never defined (see the help page).
  4. ^ a b c Poleszak E, Szopa A, Wyska E, Kukuła-Koch W, Serefko A, Wośko S, et al. (February 2016). "Caffeine augments the antidepressant-like activity of mianserin and agomelatine in forced swim and tail suspension tests in mice". Pharmacological Reports. 68 (1): 56–61. doi:10.1016/j.pharep.2015.06.138. ISSN 1734-1140. PMID 26721352. S2CID 19471083.
  5. ^ a b c d e f g h i "Caffeine". DrugBank. University of Alberta. 16 September 2013. Archived from the original on 4 May 2015. Retrieved 8 August 2014.
  6. ^ Institute of Medicine (US) Committee on Military Nutrition Research (2001). "2, Pharmacology of Caffeine". Pharmacology of Caffeine. National Academies Press (US). Archived from the original on 28 September 2021. Retrieved 15 December 2022.
  7. ^ "Caffeine". Pubchem Compound. NCBI. Retrieved 16 October 2014.
    Boiling Point
    178 °C (sublimes)
    Melting Point
    238 DEG C (ANHYD)
  8. ^ "Caffeine". ChemSpider. Royal Society of Chemistry. Archived from the original on 14 May 2019. Retrieved 16 October 2014. Experimental Melting Point:
    234–236 °C Alfa Aesar
    237 °C Oxford University Chemical Safety Data
    238 °C LKT Labs [C0221]
    237 °C Jean-Claude Bradley Open Melting Point Dataset 14937
    238 °C Jean-Claude Bradley Open Melting Point Dataset 17008, 17229, 22105, 27892, 27893, 27894, 27895
    235.25 °C Jean-Claude Bradley Open Melting Point Dataset 27892, 27893, 27894, 27895
    236 °C Jean-Claude Bradley Open Melting Point Dataset 27892, 27893, 27894, 27895
    235 °C Jean-Claude Bradley Open Melting Point Dataset 6603
    234–236 °C Alfa Aesar A10431, 39214
    Experimental Boiling Point:
    178 °C (Sublimes) Alfa Aesar
    178 °C (Sublimes) Alfa Aesar 39214
  9. ^ Nehlig A, Daval JL, Debry G (1992). "Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects". Brain Research. Brain Research Reviews. 17 (2): 139–170. doi:10.1016/0165-0173(92)90012-B. PMID 1356551. S2CID 14277779.
  10. ^ a b Reddy VS, Shiva S, Manikantan S, Ramakrishna S (2 March 2024). "Pharmacology of caffeine and its effects on the human body". European Journal of Medicinal Chemistry Reports. 10: 100138. doi:10.1016/j.ejmcr.2024.100138.
  11. ^ Camfield DA, Stough C, Farrimond J, Scholey AB (August 2014). "Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis". Nutrition Reviews. 72 (8): 507–522. doi:10.1111/nure.12120. PMID 24946991.
  12. ^ Wood S, Sage JR, Shuman T, Anagnostaras SG (January 2014). "Psychostimulants and cognition: a continuum of behavioral and cognitive activation". Pharmacological Reviews. 66 (1): 193–221. doi:10.1124/pr.112.007054. PMC 3880463. PMID 24344115.
  13. ^ Ribeiro JA, Sebastião AM (2010). "Caffeine and adenosine". Journal of Alzheimer's Disease. 20 (Suppl 1): S3-15. doi:10.3233/JAD-2010-1379. PMID 20164566.
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  17. ^ Myers RL (2007). The 100 Most Important Chemical Compounds: A Reference Guide. Greenwood Press. p. 55. ISBN 978-0-313-33758-1. Retrieved 17 June 2018.
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  19. ^ "Global coffee consumption, 2020/21". Statista. Archived from the original on 3 March 2021. Retrieved 10 March 2021.
  20. ^ Cite error: The named reference abc.net was invoked but never defined (see the help page).
  21. ^ Ferré S (June 2013). "Caffeine and Substance Use Disorders". Journal of Caffeine Research. 3 (2): 57–58. doi:10.1089/jcr.2013.0015. PMC 3680974. PMID 24761274.
  22. ^ WHO Model List of Essential Medicines (PDF) (18th ed.). World Health Organization. October 2013 [April 2013]. p. 34 [p. 38 of pdf]. Archived (PDF) from the original on 23 April 2014. Retrieved 23 December 2014.
  23. ^ Cano-Marquina A, Tarín JJ, Cano A (May 2013). "The impact of coffee on health". Maturitas. 75 (1): 7–21. doi:10.1016/j.maturitas.2013.02.002. PMID 23465359.
  24. ^ Qi H, Li S (April 2014). "Dose-response meta-analysis on coffee, tea and caffeine consumption with risk of Parkinson's disease". Geriatrics & Gerontology International. 14 (2): 430–9. doi:10.1111/ggi.12123. PMID 23879665. S2CID 42527557.
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  27. ^ American College of Obstetricians and Gynecologists (August 2010). "ACOG CommitteeOpinion No. 462: Moderate caffeine consumption during pregnancy". Obstetrics and Gynecology. 116 (2 Pt 1): 467–8. doi:10.1097/AOG.0b013e3181eeb2a1. PMID 20664420.
  28. ^ Malenka RC, Nestler EJ, Hyman SE (2009). "Chapter 15: Reinforcement and Addictive Disorders". In Sydor A, Brown RY (eds.). Molecular Neuropharmacology: A Foundation for Clinical Neuroscience (2nd ed.). New York: McGraw-Hill Medical. p. 375. ISBN 978-0-07-148127-4. Long-term caffeine use can lead to mild physical dependence. A withdrawal syndrome characterized by drowsiness, irritability, and headache typically lasts no longer than a day. True compulsive use of caffeine has not been documented.
  29. ^ American Psychiatric Association (2013). "Substance-Related and Addictive Disorders" (PDF). American Psychiatric Publishing. pp. 1–2. Archived from the original (PDF) on 1 July 2014. Retrieved 10 July 2015. Substance use disorder in DSM-5 combines the DSM-IV categories of substance abuse and substance dependence into a single disorder measured on a continuum from mild to severe. ... Additionally, the diagnosis of dependence caused much confusion. Most people link dependence with "addiction" when in fact dependence can be a normal body response to a substance. ... DSM-5 will not include caffeine use disorder, although research shows that as little as two to three cups of coffee can trigger a withdrawal effect marked by tiredness or sleepiness. There is sufficient evidence to support this as a condition, however it is not yet clear to what extent it is a clinically significant disorder.
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  31. ^ Heckman MA, Weil J, Gonzalez de Mejia E (April 2010). "Caffeine (1, 3, 7-trimethylxanthine) in foods: a comprehensive review on consumption, functionality, safety, and regulatory matters". Journal of Food Science. 75 (3): R77–R87. doi:10.1111/j.1750-3841.2010.01561.x. PMID 20492310.
  32. ^ EFSA Panel on Dietetic Products, Nutrition and Allergies (2015). "Scientific Opinion on the safety of caffeine". EFSA Journal. 13 (5): 4102. doi:10.2903/j.efsa.2015.4102.
  33. ^ Awwad S, Issa R, Alnsour L, Albals D, Al-Momani I (December 2021). "Quantification of Caffeine and Chlorogenic Acid in Green and Roasted Coffee Samples Using HPLC-DAD and Evaluation of the Effect of Degree of Roasting on Their Levels". Molecules. 26 (24): 7502. doi:10.3390/molecules26247502. PMC 8705492. PMID 34946584.