Question

In a graph of renal clearance 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

I have been asked this question in an international level competition.

The above asked question is from Drugs Excretion topic in chapter Prodrugs & Excretion of Drugs of Drug Biotechnology

Answer 1

Correct option is (c) Drug filtered as well as actively secreted

Easiest 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 an increase in plasma concentration up to a saturation level. The renal clearance will tend to decrease when the plasma concentration is at lower level.