Drug Elimination

C- When the drug is eliminated through more than one pathway for example via metabolism, renal excretion, and biliary excretion, the elimination rate will be equal to the metabolic rate plus the renal excretion rate plus the biliary excretion rate.

Metabolism

Renal excretion

Biliary excretion

The overall drug elimination rate is equal to the sum of the rates for the three pathways, and the CLT is equal to the sum of the three clearances.

CLT = CLM + CLR+ CLB

By dividing both sides of the equation by Vd:

k = km+ ke + kb

The elimination rate constant (k) = the sum of the metabolic rate constant (km) + the renal excretion rate constant (ke) the biliary excretion rate constant (kb)

Also, the total body clearance is the sum of the different organ clearances

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