Caffeine

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Contents

Introduction

Caffeine is found in tea, multiple stimulant soft drinks and coffee. It is a non-specific adenosine receptor antagonist and phosphodiesterase inhibitor. It is the most widely used neuropsychiatric stimulant.

Clinical Use

Indications

Stimulant. Mild diuretic.

Administration

Oral iv- caffeine citrate 60 mg/3 ml, solution for infusion and oral solution is used to treat primary apnoea of the premature neonate

Clinical Issues

While there is effectively no lower exposure limit for the risk of fetal growth restriction and caffeine intake[1], conflicting data exists on whether it increases risk of spontaneous abortion during pregnancy.[2][3][4]

Contra-indications

Cautions and Interactions

  • Minimise intake in pregnancy. National guidelines vary.

Side effects

Special advice

Pharmacology

At normal dosage its neuro-excitatory actions are probably mainly mediated through A2A receptors, although A1 receptors may have a role[9]. The inhibition of cAMP-phosphodiesterase may have implications at normal dosage. Its half-life in adults is approximately 3–4 hours, but it is much more prolonged in children, conditions such as pregnancy and liver disease as predicted by its predominant CYP1A2 metabolism. Its metabolic products have potential pharmacological activity in their own right being predominantly paraxanthine and smaller quantities of theobromine and theophylline.

References

  1. Maternal caffeine intake during pregnancy and risk of fetal growth restriction: a large prospective observational study. BMJ (Clinical research ed.). 2008; 337:a2332.(Epub)
  2. Klebanoff MA, Levine RJ, DerSimonian R, Clemens JD, Wilkins DG. Maternal serum paraxanthine, a caffeine metabolite, and the risk of spontaneous abortion. The New England journal of medicine. 1999 Nov 25; 341(22):1639-44.
  3. Savitz DA, Chan RL, Herring AH, Howards PP, Hartmann KE. Caffeine and miscarriage risk. Epidemiology (Cambridge, Mass.). 2008 Jan; 19(1):55-62.(Link to article – subscription may be required.)
  4. Weng X, Odouli R, Li DK. Maternal caffeine consumption during pregnancy and the risk of miscarriage: a prospective cohort study. American journal of obstetrics and gynecology. 2008 Mar; 198(3):279.e1-8.(Link to article – subscription may be required.)
  5. Cerimele JM, Stern AP, Jutras-Aswad D. Psychosis following excessive ingestion of energy drinks in a patient with schizophrenia. The American journal of psychiatry. 2010 Mar; 167(3):353.(Link to article – subscription may be required.)
  6. Hedges DW, Woon FL, Hoopes SP. Caffeine-induced psychosis. CNS spectrums. 2009 Mar; 14(3):127-9.
  7. Boos CJ, White SH, Bland SA, McAllister PD. Dietary supplements and military operations: caution is advised. Journal of the Royal Army Medical Corps. 2010 Mar; 156(1):41-3.
  8. Rogers PJ, Hohoff C, Heatherley SV, Mullings EL, Maxfield PJ, Evershed RP, Deckert J, Nutt DJ. Association of the anxiogenic and alerting effects of caffeine with ADORA2A and ADORA1 polymorphisms and habitual level of caffeine consumption. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology. 2010 Aug; 35(9):1973-83.(Link to article – subscription may be required.)
  9. Huang ZL, Qu WM, Eguchi N, Chen JF, Schwarzschild MA, Fredholm BB, Urade Y, Hayaishi O. Adenosine A2A, but not A1, receptors mediate the arousal effect of caffeine. Nature neuroscience. 2005 Jul; 8(7):858-9.(Link to article – subscription may be required.)