Dr Sharon Rees @reesprescribe
Day 1: Used for centuries as a stimulant, #caffeine was found via coffee bean analysis circa 1820, but is also found in the cocoa bean, guarana seeds, tea leaves etc; #caffeine can also be synthesised from uric acid. A methylxanthine, medical uses include neonatal respiratory stimulation and adjunctive analgesia.
Dr Sharon Rees @reesprescribe
Day 2: #caffeine + citric acid = caffeine citrate (1/2 as strong as caffeine base). Citric acid is added to enhance solubility. This is used for apnoea of prematurity in neonates. Oral solution or i.v infusion x1/day 20 mg/kg loading, then 5 mg/kg/day; adjust as necessary and monitor concentration.
Dr Sharon Rees @reesprescribe
Day 2 (cont): #caffeine in OTC analgesics range 30-65 mg/tablet; Cochrane supports improved pain relief if #caffeine dose >100 mg. Safe total daily dose <400 mg/day(½ if pregnant); 1 cup brewed coffee ~100 mg. Lots of health claims and does contain antioxidants, but relevant levels only at high doses; it is safer to eat fruit/veg!
Dr Sharon Rees @reesprescribe
Day 3: Kinetics; #caffeine has fast oral absorption/crosses the placenta (check maternal consumption pre-delivery). Hepatic metabolism via CYP1A2, NAT2, xanthine oxidase. Renal excretion; adult t1/2 3–7 hrs. Poor metabolism in children leading to prolonged t1/2 to 100 hrs at birth (monitor after stopping).
Dr Sharon Rees @reesprescribe
Day 4: #caffeine structure is like adenosine. In neonates, caffeine stimulates CNS and respiratory centres and increases basal metabolic rate (BMR). In adults, antagonises central adenosine receptors (A1 and 2) and blocks activation and sleepiness, hence stimulant effect. Dopamine release reinforces pleasure, but also leads to withdrawal symptoms.
Dr Sharon Rees @reesprescribe
Day 4 (cont): Mixed direct/indirect vascular effects which differ depending on location. #caffeine can cause smooth muscle vasoconstriction or vasodilation. This means cosmetic and increased performance (eg athletic) uses are hard to predict or quantify. Weight loss (increased BMR/reduced hunger) and lipolysis (eg cellulite) uses are also unproven.
Dr Sharon Rees @reesprescribe
Day 5: ADEs #caffeine: Neonates; restlessness, vomiting, tachycardia, tremors, seizures + increased risk of GORD. Adults; insomnia, agitation, chest pain, tachycardia, migraine, increased GORD/GI ulceration risk (NOT exhaustive). High doses are diuretic and can cause dehydration; reducing caffeine intake can improve urinary urgency/frequency.
Dr Sharon Rees @reesprescribe
Day 6: Little data for drug–drug interactions. Caffeine citrate has one ‘severe’ DDI with fluvoxamine which reduces clearance. SPC states additive effects with other xanthines eg theophylline and advises to avoid concurrent use. Consider impact of enzyme inducers eg phenytoin and inhibitors eg cimetidine (NOT exhaustive).
Dr Sharon Rees @reesprescribe
Day 7: #caffeine can affect several medical conditions, for which avoiding or reducing dose may help. Bipolar disorder (avoid), chilblains, urinary incontinence, breast pain, restless legs, migraine (NOT exhaustive). Overdose of #caffeine can lead to death eg levels over 10 g!
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In addition to the tweets, read the BNFC section on respiratory stimulants, as well as the monograph on caffeine citrate. Further, the BNF also has information on caffeine in the analgesics section, under ‘compound analgesic preparations’. Another useful source is the Summary of product characteristics for caffeine citrate – see links below.
Further reading on #caffeine
- Respiratory stimulant: https://bnfc.nice.org.uk/treatment-summary/respiratory-stimulants.html
- Caffeine citrate: https://bnfc.nice.org.uk/drug/caffeine-citrate.html
- Analgesics: https://bnf.nice.org.uk/treatment-summary/analgesics.html
- Caffeine citrate 10 mg/ml oral solution: https://www.medicines.org.uk/emc/product/5145/smpc#PRODUCTINFO
Caffeine in products is always naturally derived
TRUE or FALSE?
Caffeine looks chemically similar to adenosine
TRUE or FALSE?
Caffeine does not cross the placenta
TRUE or FALSE?
Which is TRUE?
- Caffeine alone is a strong analgesic
- Neonatal caffeine citrate concentration needs careful monitoring
- Caffeine has a longer half-life in children compared to adults
- The safe daily dose applies to all adults
At high doses, caffeine is known to:
- Cause tachycardia
- Have a calming effect
- Cause hepatotoxicity
- Improve hyperglycaemia
Caffeine supports analgesia if the dose is over 100 mg
TRUE or FALSE?
Caffeine intake can affect urinary urgency and frequency for some women
TRUE or FALSE?
Caffeine has multiple drug–drug interactions
TRUE or FALSE?
Caffeine is the most widely used psychostimulant in the world
TRUE or FALSE?
In which of the following conditions is caffeine a potential issue, with advice to ‘avoid’?
- Osteoarthritis
- Diabetes
- Asthma
- Bipolar disorder