Caffeine (metabolism)

Purine alkaloid (C₈H₁₀N₄O₂) metabolised in the liver by CYP1A2. Average half-life 5-6 hours (2-12h depending on genotype). Blocks adenosine A₁ and A₂A receptors, increasing alertness. Safe moderate dose: 400mg/day (healthy adult). Transfer to breast milk: ~1% of ingested dose.