Week 2 Objectives.docx - Pharmacokinetics A Discuss the four main processes that make up pharmacokinetics(absorption distribution metabolism and

Week 2 Objectives.docx - Pharmacokinetics A Discuss the...

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PharmacokineticsA.Discuss the four main processes that make up pharmacokinetics (absorption, distribution, metabolism, and excretion), and appropriately apply these processes to clinical usefulness.Pharmacokinetics: the study of drug movement throughout the bodyAbsorption: the movement of drug from its site of administration into the systemic circulation-Factors that affect drug absorption: rate of dissolution, surface area, blood flow, lipid solubility, pH partitioningDistribution: the movement of drugs from the systemic circulation to the sire of drug action,determined by three major factors—blood flow to the tissues, ability of a drug to exit the vascular system and the ability of a drug to enter cells Metabolism (biotransformation): the enzymatic alteration of drug structure, generally takes place in the liver -Hepatic drug-metabolizing enzymes aka P450 system-Drugs travel from the liver into the duodenum then back into the liver through the portal blood, but only certain drugs affected by this -Glucuronidation: a process that convert lipid soluble drugs to water soluble drugsby binding them to glucuronic acid. After glucuronidation, these drugs can enter the bile then pass the duodenum. Once in the intestine, some drugs are hydrolyzed by intestinal beta-glucuronidase, an enzyme that breaks the bond b/t the original drug and the gluronide moiety, releasing free drug to allow for reabsorption into the liver to restart thiscycleExcretion:the removal of drugs from the body through urine, bile, sweat, saliva, breast milk and expired air, primarily through the kidneys a.Bioavailability: a subcategory of absorption and is the fraction of an administereddose of unchanged drug that reaches the systemic circulationb.First-pass effect: when drugs are absorbed from the GI tract, they are carried directly to the liver through the hepatic portal vein before they enter the systemic circulation. If the capacity of the liver to metabolize a drug is extremely high, the drug can be completely inactivated on its first pass through the liver.c.Volume of distribution(low vs high): -Capillary beds have little resistance to departure of drugs, which allows them to pass through them into the interstitial space.

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