What do dose-response curves tell about drugs?
The graph shows the dose-response curves of 2 drugs (blue and red) that elicit the same response (effect). The upper graph is displayed on a linear or arithmic scale; the lower uses a logarithmic scale for the dose on the x-axis.
The EC50 is a measure for the potency of a drug, which is equal to the dose (concentration) at which the drug elicits 50% of its maximal effect. The blue drug is more potent, because it requires a lower dose in order to elicit 50% of the maximal response.
The following topics will give more information on dose-response curves. From now on, we will talk about drugs instead of ligand and about dose or concentration.