PSY 356 pharmacokinetics 3

PSY 356 pharmacokinetics 3 - PHARAMCOKINETICS CONTINUED A....

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PHARAMCOKINETICS CONTINUED A. Metabolism -how drugs are broken down -typically occurs in the liver (aka detoxification) a. Psychoactive drugs almost always have to be broken down in order for them to be accessible b. The more likely it is for a drug to get into the brain, the more likely it will not be excreted in its original form c. Prodrug -must undergo chemical conversion by metabolic processes before becoming an active pharmacological agent (often drugs taken orally) d. Liver -enzyme breakdown made by the cytochrome P -450 family of genes -group of enzymes and the account for all of our drug breakdown mechanisms -has been around since humans started to cook meat i. Liver tried to get ride of toxins from the body from the meat (potentially billions of years old) ii. The reabsorbed drug is eventually picked up by liver cells (hepatocytes) and enzymatically biotransformed into metabolites that are usually less fat soluble, less capable of being reabsorbed, and therefore capable of being excreted in urine iii. There are 12 P450 families -all start with CYP a. Located on the hepatocytes and some are found in the GI tract b. Several families can be found on any given hepatocyte and can detoxify a chemically diverse group of foreign substances c. Enzymes CYP-1, CYP-2, CYP-3 encode enzymes involved in most drug biotransformations i. Since those three families promote the breakdown of numerous drugs and toxins, enzyme specificity is low therefore the body d. One family (CA4 or CYP-3A4) -accounts for 50% of drug breakdowns -making it into a water soluble form i. Found in liver and GI tract
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This note was uploaded on 05/05/2011 for the course PSY 356 taught by Professor Simson during the Spring '11 term at Miami University.

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PSY 356 pharmacokinetics 3 - PHARAMCOKINETICS CONTINUED A....

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