Renal Drug Clearance: Overview

Renal clearance is defined as a constant fraction of the central volume of distribution containing the drug excreted by the kidney per unit of time.

It is calculated as the urinary drug excretion rate divided by the plasma drug concentration.

Alternatively, it can be determined by multiplying the proportion of the bioavailable dose eliminated unchanged in the urine with total body clearance.

It can also be estimated using the noncompartmental formula by observing the amount of drug excreted unchanged in the urine and the area under the curve.

Steady-state conditions allow for renal clearance calculation by evaluating the same parameters during the dosing interval.

Another method involves considering the drug's mass balance cleared by the kidney and excreted through urine.

Advanced approaches include data modeling and fitting with compartmental methods that require simultaneous modeling of observed systemic concentrations and excreted urinary amounts.