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23 Cards in this Set
- Front
- Back
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Drug Distribution
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Key is that it is not even, drug distribution depends on many factors.
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What do Plasma Proteins do to drug distribution?
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Drugs bind to stuff such as plasma proteins which lowers the free drug concentration and if its bound can not breach BBB.
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How will a drug become increasingly bound?
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Dissociation of durg (KD) becomes lower (binding affintiy becomes higher) and free drug concentration (X) becomes lower.
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Why does binding slow disapperatance of the drug from the blood?
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B/C only free drug can be filtered through the glomeruli and transfer by diffusion across capillary membranes
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What is a main componinte in the compute the bound fraction of a drug?
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P = the total protein conc. b/c people with liver disfunction may have hypoprotein levels.
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What easier to measure the rate or the amount of binding?
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The amount b/c the rte occurs in milliseconds.
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What must be known to measure the amount of binding?
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Which proteins are involved in binding and the plasma conc. of these target proteins.
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What is hyperalbuminemia and how does it occur?
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Increase levels of albumin in the blood RARE. Occurs after acute and severe dehydration.
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What is hypoalbuminemia and how does it occur?
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low levels of albumin the blood. MORE COMMON. Can affect free drug levels.
Decreased Synthesis: Liver disease, malbutrition, malabsorbtion Loss of Proteins: Massive burns, glomerular injury, inflammation Nonspecific: Pregnancy, aging, cardiac failure. |
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When is there a possibility that a drug interaction will produce a toxic effect?
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Whenever the protein bound fraction of a drug equals or greater than 80% of its total plasma concentration
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What do acidic drugs and basic drugs bind almost exculsively to?
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Acidic drugs to albumin
Basic drugs to alpha-1-acid glycoprotein |
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What will a drug that is highly bound creat for a patient?
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There is a greater chance of an undesirable effect.
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What is cell constutuents?
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Complexation of a drug with some part of a cell, anotherthing drugs can bind to. ie binding of mercuric ions w/ -sh groups
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What is Sequetration in Skeltal Sytem?
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binding of drugs in bones or teeth such as tetracycline binds to ca+ in teeth.
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what is L/W partition coefficient?
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Drugs that are highly lipid soluble/ high l/w tend to accumulate in adipose tissue. They are also more likely to be abused.
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What is selective permeability of cell membranes?
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Some molecules are preferentialy taken up by certan cell membranes ie iodide ion by cells of thyroid.
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What does a high drug concentration in a given tissue mean?
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just because thedrug concentratoin is highest in a given tissue DOES NOT mean thathte tissue is the action poit of hte drug; in reality it is probably not.
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What is a structureal feature that will decrease permeability in the BBB?
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Glial cell (astrocytes) located next to the capillaries.
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How does a drug gain access to the BBB?
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Drug must exit capillaries of CNS and traverse boh the capillary endothelium and membranes of the glials cells.
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What characteristics do drugs that readily pentrate the CNS have?
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Low degree of ionization
Low binding to plasma proteins High L/W (nonionized form) Small molecular size |
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What is latentiation?
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A reversible process of adding a lipophilic group to a molecule to increase pernetration fo biologicla membranes (BBB). Once inside the group is removed by enzyme of target tissue and original molecule is generated.
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What is the placental barrier?
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not a true barrier and drug will pretty much pass through it into fetal circulation, except for compounds with strong electronegative or electropositive charges or high MW.
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How do antibody globulins pass into the fetus?
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Buy selective mechanism is present since albumins have a LOWER MW but penetrate more slowly.
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