Potency is best described as which of the following?

Potency is best described as which of the following?

• A. The maximum achievable effect
• B. The relationship between blood concentration and pharmacologic response, where a lower dose indicates higher potency
• C. The time to onset of action
• D. The therapeutic index value

Answer: (B)

Potency is about how much of a drug is needed to produce a given effect. A drug that achieves the same effect at a lower dose is more potent. This is reflected in the dose–response relationship: if a lower dose (or lower blood concentration) yields the same response, potency is higher. It does not measure the maximum effect—that's efficacy. The time to onset and the therapeutic index relate to onset speed and safety margin, not potency. So the statement that links potency to the amount of drug needed to reach a given response, with a lower dose indicating higher potency, best describes potency.

Potency is about how much of a drug is needed to produce a given effect. A drug that achieves the same effect at a lower dose is more potent. This is reflected in the dose–response relationship: if a lower dose (or lower blood concentration) yields the same response, potency is higher. It does not measure the maximum effect—that's efficacy. The time to onset and the therapeutic index relate to onset speed and safety margin, not potency. So the statement that links potency to the amount of drug needed to reach a given response, with a lower dose indicating higher potency, best describes potency.