Paraxanthine
Paraxanthine, an alkaloid. Major (≈84%) CYP1A2 metabolite of caffeine — N3-demethylated to 1,7-dimethylxanthine. A non-selective adenosine… Oral half-life 3.1 h.
Major (≈84%) CYP1A2 metabolite of caffeine — N3-demethylated to 1,7-dimethylxanthine. A non-selective adenosine receptor antagonist (Ki at A1/A2A within 2-3× of caffeine itself) and a phosphodiesterase inhibitor. Responsible for a substantial fraction of caffeine's late-half-life CNS effects since paraxanthine accumulates in plasma while caffeine drops. Trialed as a stand-alone supplement / nootropic with claims of cleaner subjective tolerability than caffeine — less anxiogenic effect at equivalent A2A occupancy. PK (Lelo 1986 PMID:3741224 + caffeine metabolism literature): Caffeine's major 1-N-demethylated metabolite (CYP1A2 product — cross-link: caffeine_demethylation pathway); also dosed directly as a research/supplement compound. t½ 3-4 h, Tmax 1-2 h, F estimated 70% from PO-dosed studies. Apparent Vd 40 L. CYP1A2 substrate same as caffeine parent (smokers/inducers clear faster); minimal CYP-perpetrator activity. Pharmacology similar to caffeine but more A2A-selective + claims of reduced anxiety vs caffeine (limited human data).
Pharmacokinetics
- Oral — t½ 3.1 h · F 70% · Vd 40 L
Sources: PMID:3756065