When studying drug concentration and effect, what is the upper limit of the therapeutic window known as?

The upper limit of the therapeutic window is referred to as the minimum toxic concentration. The therapeutic window represents the range between the minimum effective concentration of a drug, which is the lowest concentration that produces the desired therapeutic effect, and the minimum toxic concentration, which is the concentration at which the drug begins to produce adverse effects. Understanding this range is crucial in pharmacotherapy, as it helps healthcare providers prescribe medications safely and effectively, avoiding concentrations that could lead to toxicity while ensuring therapeutic efficacy.

Onset of action and duration of action pertain to how quickly a drug begins to work and how long its effects last, respectively, but they do not define the boundaries of the therapeutic window. The term "therapeutic window" itself describes the range between the minimum effective dose and the minimum toxic concentration but does not specify the upper limit directly. Thus, the correct term for the upper limit is indeed the minimum toxic concentration.