PHARMACOKINETICS
VENOUS EQUILIBRIUM
MODEL
VENOUS EQUILIBRIUM MODEL
 Low Extraction Drug:
 CL=
 F*=
 High Extraction Drug:
 CL=
 F*=
VENOUS EQUILIBRIUM MODEL
 If a drug has a ER=0.2 and fup is increased, describe what
happens to:
 Css, IV:
 Css,u IV:
 Css PO:
 Css,u PO:
VENOUS EQUILIBRIUM
 If a drug has a ER=0.2 and Q is increased, describe what
happens to:
 Css, IV:
 Css,u IV:
 Css PO:
 Css,u PO:
VENOUS EQUILIBRIUM
 If a drug has a ER=0.2 and CLint is decreased, describe what
happens to:
 Css, IV:
 Css,u IV:
 Css PO:
 Css,u PO:
VENOUS EQUILIBRIUM
 If a drug has a ER=0.9 and CLint is decreased, describe what
happens to:
 Css, IV:
 Css,u IV:
 Css PO:
 Css,u PO:
VENOUS EQUILIBRIUM
 If a drug has a ER=0.9 and Q is increased, describe what
happens to:
 Css, IV:
 Css,u IV:
 Css PO:
 Css,u PO:
VENOUS EQUILIBRIUM
 If a drug has a ER=0.9 and fup is increased, describe what
happens to:
 Css, IV:
 Css,u IV:
 Css PO: Won’t ask you
 Css,u PO: Won’t ask you
VENOUS EQUILIBRIUM
CL
Low E drugs:
Dec Q
Inc CLint
Inc fup
Vss
T1/2
VENOUS EQUILIBRIUM
VENOUS EQUILIBRIUM
 A patient has a yeast infection for which his physician
prescribed ketoconazole. He is also taking aspirin 81 mg,
simvastatin 40 mg, carvedilol 12.5 mg BID, and lisinopril 10
mg. What drug interaction is present?
 What happens to:
 Vmax
 Km
 Clint
 When do you expect this to happen? (Immediately or will it
take time?)
VENOUS EQUILIBRIUM
 Rifampin induces the metabolism of a substrate.
 What happens to:
 Km
 Vmax
 Clint
 When do you expect to see this interaction?
PHARMACOKINETICS TUTORING
 Does the dose rate need to be changed for a drug given orally
with the following characteristics when it is administered with
an inhibitor:
 CL,T=1200ml/min
 Fe=0.20
VENOUS EQUILIBRIUM
 TIPS:
 ONLY if Css,u changes would you change DR.
 Practice the charts in your notes!
 Pay attention to practice questions on recitation.