Answer to Practice Problem #2 Pharmacokinetic Drug Interactions Tutorial:

 

By causing a reduction in the contractility of the heart, propranolol will cause a reduction in the hepatic blood flow (as a result of the reduced cardiac output). Since lidocaine is a high hepatic intrinsic clearance drug, its hepatic clearance is a function of liver blood flow. The reduction in liver blood flow caused by concurrent administration of propranolol would be expected to result in a decrease in the hepatic clearance of lidocaine.      Reducing the hepatic clearance will result in an increase in the steady-state concentration of the drug. Thus, addition of propranolol to this patients regimen may necessitate a reduction in the infusion rate of lidocaine.

 

Last revised 07/13/05

 

ã 2005 -  Craig K. Svensson, Pharm.D., Ph.D.

 

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