This interactive graph allows you to easily track the deacy of a drug effect as defined by the Emax model.
First set the dose as high as you need to to make sure you get up to Emax. For starters, 20,000 would work.
Next, drag the EC50 slider to the far left so the EC50 is lowest at 20.
Hit 'Return', and you will plot both the Concentration-time and Effect-time profiles.
You can adjust either Dose or EC50 to focus on different parts of the decay curve.