For IV dosing, how does increasing clearance affect AUC_iv if dose is fixed?

• A. AUC_iv decreases
• B. AUC_iv increases
• C. AUC_iv remains unchanged
• D. AUC_iv doubles

Answer: (A)

For IV dosing, systemic exposure (AUC) is determined by how much drug you administer and how quickly the body clears it. Since IV delivers 100% of the dose into the bloodstream, AUC equals Dose divided by Clearance (AUC = Dose / CL). With the dose fixed, any increase in clearance makes the denominator bigger, so the overall AUC decreases. This is the intuitive idea: faster clearance means the drug doesn’t stay in the body as long, leading to less total exposure. If clearance doubles, AUC would roughly halve, illustrating the inverse relationship. The other options ignore this fundamental inverse link between clearance and AUC for IV dosing.