Warfarin Pharmacogenomic Dosing Simulator

Warfarin has one of the narrowest therapeutic windows of any common drug, and two genes — CYP2C9 (how fast the liver clears it) and VKORC1 (how sensitive its molecular target is) — explain much of why a "standard" dose overdoses some patients and underdoses others. This simulator picks a CYP2C9 metabolizer phenotype and a VKORC1 sensitivity genotype, computes a genotype-guided starting dose, then runs a real indirect-response pharmacokinetic/pharmacodynamic model forward in simulated days: daily oral dosing builds up a plasma warfarin level in a 3D bloodstream, which inhibits vitamin-K-dependent clotting factor synthesis in the liver, which in turn drives the INR (the clinical measure of blood clotting time) up or down. A live chart tracks INR against the 2.0–3.0 therapeutic window and the percentage of time spent inside it, showing directly why fixed, one-size-fits-all warfarin dosing is a genuine patient-safety problem.