Not how much you gave,
but how much is there now
A drug does not work by dose. It works by the concentration where the target is. The same 100 mg vanishes in half an hour for one drug and lingers for three days for another.
Over these 20 lessons you compute by hand the four constants behind that difference — clearance, volume of distribution, half-life and AUC — then work through oral absorption and first pass, steady state and troughs, saturable elimination, and finally deriving a first-in-human dose from mouse data. Python runs right inside this page.
How you'll learn
Start with what the height, the slope and the area of a concentration-time curve each mean. The four constants are just names for reading that curve.
You add up the trapezoids for AUC yourself, pull the half-life out of a slope, and derive CL and Vd from it — instead of copying numbers a program printed.
Widen the interval and dosing gets easier — and the trough gets deeper. Raise the dose and the effect saturates while the toxicity does not. You turn each slider yourself.
The last five lessons are the road from preclinical data to a first-in-human dose — including where the body-surface conversion and the safety factor come from.