Example : A new antibiotic is eliminated by liver metabolism (50%) and renal excretion (50%). The hepatic extraction ratio of this antibiotic is 0.4 in a patient who has liver blood flow of 1.5 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 iv dose of 300 mg of this drug ?

Hepatic clearance

CLH = Q E

CLT

CLT =

CLH

fm

AUC:

AUC =

Dose

CLT

Answer :

CLH = 1.5 L/min x 0.4 = 0.6 L/min
CLT =

0.6 L/min

0.5 = 1.2 L/min
AUC =

300 mg

1.2 L/min = 250 mg-min/L
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