Podcast 1007: Caffeine Pharmacology

Podcast 1007: Caffeine Pharmacology

From Emergency Medical Minute by Emergency Medical Minute

May 25, 2026 · 5 min

About this episode

This episode discusses the pharmacology of caffeine, its effects on adenosine receptors, and its implications for sleep and wakefulness.

Contributor: Travis Barlock, MD Educational Pearls: Caffeine Geography and Types: Caffeine is found throughout the world and has evolved independently in various plants that are not evolutionarily related through direct lineage, but rather demonstrate convergent evolution (i.e. different species evolve the same traits). These plants use caffeine as an insecticide. Examples of caffeine sources include coffee, tea, yerba-mate, guaraná, cacao, and yaupon holly. Roughly 85% of Americans are estimated to consume caffeine daily. Caffeine Pharmacology in Humans: In humans, caffeine is a nonselective competitive antagonist (blocker) of adenosine receptors (A1 and A2A). During waking hours, neuronal metabolic activity consumes ATP, and a byproduct of ATP hydrolysis is created: adenosine. Adenosine proceeds to build a "sleep pressure". Acting on A1 and A2A adenosine receptors to induce sleep (on A1, it suppresses neuronal "wakefulness" and on A2A it is believed to be an inducer of sleep). Caffeine, by blocking those receptors, blunts sleep induction and feelings of being tired. Caffeine has a half-life of around 6 hours, and a quarter life of approximately 12 hours, which is when the…

People in this episode

Guest: Travis Barlock, MD

Topics covered

Mentioned in this episode

Products: caffeine, coffee, tea, yerba-mate, guaraná, cacao, yaupon holly

Places: America

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