The therapeutic window of the medication refers to?

A drugs therapeutic window is the minimum dosage necessary for a patient to benefit from the main effects intended of a specific drug. While main effects become present and are maximized, side effects are minimized. This allows the patient to benefit from the therapeutic effect of the drug without suffering side effects that are more likely to be present if the optimum dosage is exceeded. Ref: Human Drug Metabolism: An Introduction By Michael D. Coleman.