Which term describes the maximum achievable effect of a drug, regardless of dose?

Which term describes the maximum achievable effect of a drug, regardless of dose?

• A. Emax
• B. Potency
• C. Efficacy
• D. TI

Answer: (A)

The maximum effect a drug can produce, regardless of how much you dose, is described by Emax. This is the top of the dose–response curve—the ceiling the body reaches when receptors become saturated or the system can no longer amplify the signal. Increasing the dose won’t push the response higher than this ceiling. Potency, in contrast, tells you how much drug is needed to reach a given level of effect, not how high the effect can go. Efficacy is often used to refer to the maximum effect, but the precise term for the upper limit is Emax. TI is the therapeutic index, a safety measure comparing toxic to therapeutic doses and not about the maximal response.

The maximum effect a drug can produce, regardless of how much you dose, is described by Emax. This is the top of the dose–response curve—the ceiling the body reaches when receptors become saturated or the system can no longer amplify the signal. Increasing the dose won’t push the response higher than this ceiling. Potency, in contrast, tells you how much drug is needed to reach a given level of effect, not how high the effect can go. Efficacy is often used to refer to the maximum effect, but the precise term for the upper limit is Emax. TI is the therapeutic index, a safety measure comparing toxic to therapeutic doses and not about the maximal response.