A PDE9 inhibitor and adenosine A1 and A2 receptor antagonist (Kis = 35 and 22 μM, respectively in equine forebrain tissues); is the main metabolite of caffeine in humans; increases locomotor activity and counteracts adenosine receptor agonist-induced motor depression in rats not habituated to caffeine; induces a significant increase in striatal cGMP and extracellular striatal dopamine concentrations in vivo; promotes wakefulness and increases locomotor activity and core temperature in narcoleptic transgenic mice without increasing behavioral anxiety,