MetabolismObjectives:
=> 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.
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