Among dose-response curves, the one with the greatest maximal effect indicates higher:

• A. Potency
• B. Efficacy
• C. Slope
• D. Threshold

Answer: (B)

Understanding dose-response curves, the greatest maximal effect reflects how much of the response a drug can produce at peak exposure—that is its efficacy. Potency is about the dose needed to reach a given level of effect (a lower dose means higher potency, not a higher ceiling). The slope describes how steeply the response rises with dose, not the maximum achievable response. Threshold is simply the smallest dose that begins to produce an observable effect. So, the largest maximal effect points to the highest efficacy. For example, a drug that can achieve 100% effect at its top dose has higher efficacy than one that tops out at, say, 60%, regardless of the doses required to reach those levels.