Urinary Excretion Rate Method: Example

Determination of renal clearance There are two method. Excretion rate method and the urinary recovery method. The excretion rate method in the top formula and the urinary recovery method in the bottom. Here let’s look at one example. The first column time. The urine is collected over several aliquot, over 24 hours. The concentration of the drug in the urine aliquot. The volume of the urine collected. And then the excretion rate of the drug. And the amount of drug excreted in a particular aliquot. And the total recovery indicated by the number in red. Therefore, by excretion rate method. Here we have time concentration and the excretion rate.

If we plot the excretion rate on the y-axis and concentration on the x axis, then we would obtain a straight line and the slope of that straight line indicate the renal clearance of the drug. In this case is 9.8 liter per hour. Here we have the plasma concentration versus time plot. Time and the concentration in the second column. And here is the curve. Plasma concentration versus time curve. And the based on this plasma concentration. We can compute an area under the curve extrapolated to time infinity. And then the clearance is computed by dose divided by area under the curve. So this concludes this lecture of renal clearance. So I will see you next time. Good luck.