Question

Drug T was administered (iv) to a volunteer, and urine was collected after 60 minutes. The concentration of T in urine was 10 mg/ml, and the volume of urine was 30 mls. Blood was drawn, and the concentration of T in plasma was determined to be 0.04 mg/ml.

            a) Calculate the renal clearance of T.

            b) Based on the answer you calculated for part a, what mechanism(s) are involved in renal clearance of T?  

Answer 1

CL renal =urine flow*urine concentration/plasma concentration

Urine flow=30mls

IUrine concentration=10mg/ml

plasma concentration=0.04mg/ml

Convert sec to minutes

ie 30/60=0.5m

0.5*10/0.04=125

b Patients renal function is proportional to drugs renal clearanceA drugs dosing is adjusted in patients with renal dysfunction based on whether the drug is excreted through the kidneys and whether increased drug levels are associated with adverse effects.Sometimes renal clearance is artificially reduced by inhibiting the renal tubular secretion of the drug.This prolongs the drugs half-life and produce undesired accumulation.Renal clearance of a weak acid or base is artificially increased by acidification or alkalinization of urine and result in increased ion trapping of the drug in the urine.