What types of drug responses are described?

• A. Immediate or delayed
• B. Quantitative or qualitative
• C. Reversible or irreversible
• D. Local or systemic

Answer: (B)

Responses to drugs can be described as either quantitative or qualitative. A quantitative (graded) response is one where the magnitude of the effect scales with the dose or concentration—higher doses produce greater effects, and you can measure a continuous range of responses, like changes in blood pressure, pain intensity, or enzyme activity. A qualitative (all-or-none) response, on the other hand, is observed as a yes/no outcome in individuals—at a given dose, some subjects respond and some do not, so the data are analyzed as the proportion that respond rather than the amount of effect. This distinction helps in both designing experiments and interpreting how a drug’s effect can be measured across a population. The other descriptions—immediate versus delayed, reversible versus irreversible, and local versus systemic—describe timing, duration, or distribution, not how the response itself is categorized.