Methylated xanthine found in cocoa. Weaker adenosine A1/A2A antagonist than caffeine (A2A Ki ~14 µM vs caffeine's ~2.4 µM) and weaker PDE inhibitor. Longer plasma t½ (~7 h vs caffeine's ~5 h). Mild vasodilator. Highly toxic to dogs + cats (slow xanthine metabolism in those species).
Half-Life (t½)
PO: 7.1h
Dosing Guidelines
PO: Typical 117 mg (Range: 50–250 mg)
Target Organ Systems
nervous
cardiovascular
Interactions
Caffeine (synergistic): Both share CYP1A2 metabolism. Cocoa's combined caffeine + theobromine content drives the milder stimulant profile vs. pure caffeine.