Question

In a graph of rate of excretion versus plasma drug concentration, which kind of drug will give the below shown curve?

(a) Drug excreted only by filtration

(b) Drug filtered and actively reabsorbed

(c) Drug filtered as well as actively secreted

(d) Drug reabsorbed actively

The question was posed to me in an online quiz.

My doubt stems from Drugs Excretion topic in chapter Prodrugs & Excretion of Drugs of Drug Biotechnology

Answer 1

Right choice is (c) Drug filtered as well as actively secreted

The explanation: The drugs which are secreted or reabsorbed, the rate increases with an increase in plasma concentration to a point where saturation occurs. Drugs that are actively secreted, the rate of excretion increases with increase in plasma concentration up to a saturation level. A drug that will not be bound to the plasma proteins and excreted by only filtration will have linear relationship between the rate of excretion and plasma drug concentration.