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XVII. Metabolism

XVII Metabolism


=> To describe the various processes by which a drug may be metabolized in the body

=> To understand the relationship between the parameters hepatic clearance, hepatic blood flow, fraction unbound, and free intrinsic clearance

The body has another way of deactivating drugs in the body. This method of elimination is metabolism or biotransformation. Metabolic processes, in general, have the overall effect of converting drug molecules into more polar compounds. Again, in general, the effect of this should be to decrease tubular re-absorption in the kidney and thus increase drug elimination. Generally, it also means an immediate loss of pharmacological activity because transport into the site of action is hindered (less lipid soluble) or the molecule no longer fits into the receptor site. There are exceptions however, and a number of `new' drugs have been discovered as active metabolites.

Metabolism takes place by enzymatic catalysis. Most metabolism occurs in the liver although other sites have been described, such as intestinal wall, kidney, skin, blood.

This page was last modified: 12 February 2001

Copyright 2001 David W.A. Bourne

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