Which statement correctly describes the relationship between potency and dose?

Which statement correctly describes the relationship between potency and dose?

• A. A drug with greater potency requires a lower dose to achieve a given effect.
• B. A drug with greater potency requires a higher dose to achieve the same effect.
• C. Potency refers to the maximum effect; Efficacy is the dose required.
• D. Potency and efficacy are identical.

Answer: (A)

Potency describes how much drug is needed to produce a given effect. A drug that is more potent reaches that effect at a lower dose, so it requires less substance to achieve the same response. For example, if one drug achieves a specific effect at a small dose while another needs a much larger dose for the same effect, the first is more potent. This concept is about the amount needed, not the maximum size of the effect. Efficacy is about how strong the effect can be once produced, regardless of the dose. Two drugs can have the same efficacy but different potencies, and potency and efficacy are not the same. Therefore, a drug with greater potency requires a lower dose to achieve a given effect.

Potency describes how much drug is needed to produce a given effect. A drug that is more potent reaches that effect at a lower dose, so it requires less substance to achieve the same response. For example, if one drug achieves a specific effect at a small dose while another needs a much larger dose for the same effect, the first is more potent. This concept is about the amount needed, not the maximum size of the effect. Efficacy is about how strong the effect can be once produced, regardless of the dose. Two drugs can have the same efficacy but different potencies, and potency and efficacy are not the same. Therefore, a drug with greater potency requires a lower dose to achieve a given effect.