psychostimulant drug pathway caffeine drug pathway 2015-12-07T08:35:37Z PW:0002317 The pharmacokinetics and pharmacodynamics pathway of caffeine, a psychostimulant of the methylxanthine class. It can confer some protective effects against some conditions. It is largely considered safe but the pure powdered caffeine, available as dietary supplement, can be lethal in higher amounts. Genetic variations can result in changes in drug availability and can cause differences in the response of the organism to the drug. pathway vpetri