On the Drug Response Curve, what is the x-axis and what is the y-axis?

• A. Dose is the x-axis and response is the y-axis
• B. Response is the x-axis and dose is the y-axis
• C. Time is the x-axis and dose is the y-axis
• D. Dose is the y-axis and response is the x-axis

Answer: (A)

The x-axis shows dose—the amount of drug given—while the y-axis shows the biological response or effect. This arrangement lets you see how increasing dose generally increases the observed effect until it plateaus. A typical curve is sigmoidal on a log-dose plot, highlighting how potency shifts the curve left or right (lower dose for the same effect means higher potency) and how efficacy determines the maximum possible response on the y-axis. If you plotted time on the x-axis, you’d be looking at how the effect changes over time, not the direct dose–response relationship, and reversing the axes would make the interpretation nonstandard.