Can be measured by assessing graded or quantum response:
Graded Response
- Measures the efficacy of a receptor-effector in a particular system (e.g. tissue, animal or patient)
- Measures effect on a continuous scale
- Used to plot drug concentration vs. response on a graded dose-response curve
- Examples of graded response include: effect of GTN on arterial pressure, streptomycin on protein synthesis etc.
Quantal response
- Measures the efficacy of a receptor-effector in a population, where the effect is binary on each individual (present or absent)
- Measures effect on a percentile scale, describing the size of population in which the effect is seen
- Used to plot drug dose vs outcome occurrence on a quantal dose-response curve
- Examples include: effect of aspirin in reducing MI occurrence etc.