Chronopharmacology: Circadian Dosing Simulator (2D)

Drug clearance is not constant through the day — hepatic CYP450 enzyme activity rises and falls on its own 24-hour rhythm, so the exact same dose of the exact same drug can behave very differently depending on when it is taken. This simulator runs a real one-compartment pharmacokinetic model (first-order absorption, RK4-integrated, time-varying elimination-rate constant) and renders it as a draggable 24-hour clock dial next to the resulting 48-hour plasma-concentration curve, colour-coded against a therapeutic window and a toxic threshold, with the clearance-rate rhythm itself plotted underneath. Drag the dosing-time handle around the clock while holding the dose fixed and watch the peak concentration and time-above-toxic-threshold readouts change — the mechanic behind real chronotherapy scheduling.