If the concentration-time curve shows a decreasing trend, what does this indicate about the rates of absorption and elimination?

If the concentration-time curve shows a decreasing trend, what does this indicate about the rates of absorption and elimination?

• A. Absorption exceeds elimination
• B. Equilibrium between absorption and elimination
• C. Elimination exceeds absorption
• D. Plasma concentration increases

Answer: (C)

A decreasing concentration-time curve means the body is removing drug faster than it is being absorbed. When elimination rate exceeds absorption rate, net drug in the plasma declines over time, so the curve falls. If absorption were faster than elimination, the concentration would rise; if they were balanced, the curve would plateau; a rising curve would indicate increasing concentration due to absorption outpacing elimination.

A decreasing concentration-time curve means the body is removing drug faster than it is being absorbed. When elimination rate exceeds absorption rate, net drug in the plasma declines over time, so the curve falls. If absorption were faster than elimination, the concentration would rise; if they were balanced, the curve would plateau; a rising curve would indicate increasing concentration due to absorption outpacing elimination.