Find out the correct option for the marked place in the given

find-out-the-correct-option-for-the-marked-place-in-the-given

Find out the correct option for the marked place in the given picture of the rate of excretion versus midpoint time of urine collection period curve.

A. (dXu/dt)max

B. (tu)max

C. Xu

D. Cmax

I had been asked this question in class test.

The question is from Bioavailability in section Compartment Modelling, Non Linear Pharmacokinetics, Bioavailability and Bioequivalence of Drug Biotechnology

Correct choice is A. (dXu/dt)max

The best explanation: (dXu/dt)max is the maximum urinary excretion rate. This is obtained from the peak of the rate of excretion versus midpoint time of urine collection period. It is analogous to Cmax from plasma level studies since the rate of appearance of drug in the urine is proportional to its concentration in circulation. Its value increases as the rate of absorption increases. (tu)max is the time for maximum excretion rate, its value decreases as the absorption rate increases. Xu is the cumulative amount of drug excreted in the urine.