From the following, which corresponds to quicker onset?

From the following, which corresponds to quicker onset?

• A. Delayed onset: shift right
• B. Lower absorption: shift down
• C. Quicker onset: shift left
• D. Greater absorption: shift up

Answer: (C)

Onset is about how quickly the drug starts producing an effect after dosing. If you think of a graph of effect versus time, reaching the same level of effect sooner means the curve has moved to the left. So a quicker onset corresponds to a leftward shift, because the effect appears earlier. A rightward shift would mean the effect takes longer to appear (delayed onset). A downward shift implies a smaller effect at the same times, and an upward shift implies a greater effect at the same times, but neither necessarily means faster onset. Hence the quicker onset is represented by the leftward shift.

Onset is about how quickly the drug starts producing an effect after dosing. If you think of a graph of effect versus time, reaching the same level of effect sooner means the curve has moved to the left. So a quicker onset corresponds to a leftward shift, because the effect appears earlier. A rightward shift would mean the effect takes longer to appear (delayed onset). A downward shift implies a smaller effect at the same times, and an upward shift implies a greater effect at the same times, but neither necessarily means faster onset. Hence the quicker onset is represented by the leftward shift.