Quantal dose responses refer to which type of pharmacologic effect?

• A. All-or-none pharmacologic effect, relates dose to frequency of effect (analgesia, sleep or lethal dose of anesthetics).
• B. A continuous measure of effect across individuals.
• C. A dose–response relationship that follows a continuous scale of effect.
• D. A measure of time to onset of action.

Answer: (C)

Quantal dose–response focuses on binary outcomes within individuals (response or no response) and links the dose to the proportion of individuals that exhibit that response. In practice, you observe whether each subject responds at a given dose and then plot the fraction of responders across doses, yielding a curve that shows how the likelihood of the effect increases with dose. This emphasizes frequency of the effect in a population rather than how large the effect is in each person. By contrast, a graded dose–response describes the magnitude of effect on a continuous scale within individuals. Time to onset is a different concept altogether. So the essential idea is an all-or-none effect at the individual level, with dose related to the frequency of response across the population.