A CYP450 metabolizer genotype describes a population's average drug clearance, but real patients who share a genotype still vary around that average — this simulator makes that variability visible. A cohort of 121 virtual patients, each running the same real one-compartment pharmacokinetic model as a single-patient simulation but with its own randomly sampled clearance around the selected genotype's mean, is given one identical dosing regimen. Each patient renders as a 3D column whose height and color track their live blood concentration in real time, colored blue below the therapeutic floor, green inside the window and red above the toxic ceiling. Adjust dose, interval and inter-individual variability to see what fraction of a real, non-identical population a single fixed regimen actually keeps safe and effective.