Example : A new antihypertensive drug is completely metabolized by the liver. The hepatic extraction ratio of this drug is 0.75 in a patient who has liver blood flow of 1.6 L/min. Calculate the hepatic clearance and the total body clearance of this drug in this patient. What is the expected AUC observed after administration of a single oral dose of 300 mg of this drug ? (The drug is completely absorbed to the portal circulation)

Hepatic clearance

CLH = Q E

CLT

CLT =

CLH

fm

AUC:

AUC =

Dose

CLT

Where

F = 1 - E

Answer :

CLH = 1.6 L/min x 0.75 = 1.2 L/min
CLT =

1.2 L/min

1 = 1.2 L/min
F = 1 - 0.75 = 0.25
AUC =

(0.25)300 mg

1.2 L/min = 62.5 mg-min/L
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