Sunday, January 27 (2019); Pharmacodynamics
Potency is the concentration (EC50) or dose (ED50) of a drug required to produce 50% of that drug’s maximal effect. Efficacy is the maximum effect which can be expected from this drug (i.e. when this magnitude of effect is reached, increasing the dose will not produce a greater magnitude of effect). A drug, when occupying the receptor, may produce a complete response, or no response, or some partial response. Intrinsic activity is the drug's maximal efficacy as a fraction of the maximal efficacy produced by a full agonist of the same type acting through the same receptors under the same conditions.