What are the two main types of dose-response relationships?

What are the two main types of dose-response relationships?

• A. Graded and Quantal
• B. Linear and Sigmoidal
• C. Immediate and Delayed
• D. Time-based and Dose-based

Answer: (A)

Two main ways pharmacologists describe how a drug’s effect changes with dose are graded responses and quantal responses. A graded response measures the magnitude of effect in a single subject as the dose increases—this is a continuous measure, like how much pain relief or enzyme activity changes, and the resulting curve is often sigmoidal when plotted against log dose. A quantal response, on the other hand, looks at an all-or-none outcome across a population at each dose—whether each subject achieves the predefined effect. Data are shown as the percentage of responders at each dose, which allows determination of a dose that achieves a given level of effect in the population (such as the ED50). The other options describe curve shapes or timing rather than the fundamental distinction between measuring continuous magnitude in an individual versus the proportion of individuals who respond.

Two main ways pharmacologists describe how a drug’s effect changes with dose are graded responses and quantal responses. A graded response measures the magnitude of effect in a single subject as the dose increases—this is a continuous measure, like how much pain relief or enzyme activity changes, and the resulting curve is often sigmoidal when plotted against log dose. A quantal response, on the other hand, looks at an all-or-none outcome across a population at each dose—whether each subject achieves the predefined effect. Data are shown as the percentage of responders at each dose, which allows determination of a dose that achieves a given level of effect in the population (such as the ED50). The other options describe curve shapes or timing rather than the fundamental distinction between measuring continuous magnitude in an individual versus the proportion of individuals who respond.