Which term refers to the amount of drug required to achieve the desired therapeutic effect?

• A. Dose
• B. Medication Concentration
• C. Pharmacodynamics
• D. Potency

Answer: (B)

Potency is the amount of drug needed to produce a given effect. A more potent drug achieves the same therapeutic response with a smaller amount, while a less potent one requires a larger amount. This concept is about the quantity required to reach the effect, not the actual dose given or the drug’s concentration in solution or in blood. Dose is the physical amount administered, and concentration refers to how much drug is present per unit volume; neither directly answers how much is needed to achieve the effect. Therefore, potency best fits the idea of the "amount of drug required" to reach the therapeutic outcome.