If a patient vomits after taking an oral drug, how does this affect the plasma concentration-time curve?

• A. It shifts the curve upward (higher concentrations).
• B. It delays onset but increases peak concentration.
• C. It results in a lower peak concentration and overall downward shift.
• D. It has no effect.

Answer: (C)

Vomiting after an oral dose interrupts absorption, so less drug reaches the bloodstream. With less drug absorbed, the peak plasma concentration is reduced and the overall curve sits lower than normal, reflecting decreased systemic exposure. If any portion is absorbed before vomiting, you might see a small early rise, but the remaining curve will still be lower. This aligns with a lower peak concentration and an overall downward shift of the curve. The other descriptions don’t fit because vomiting cannot cause a higher peak, nor would it leave the curve unchanged.