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18 Cards in this Set
- Front
- Back
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giving a medication sublingually bypasses what?
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1st pass metabolism, allows drug to go into capillary network and go to systemic circulation
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how is a drug transported from the GI tract?
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passive diffusion or active transport
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most drugs are what?
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weak acids or weak bases
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if a drug has a very large molecular weight or binds extensively to plasma proteins then it most likely distributes to where?
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plasma compartment
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if a drug has a low molecular weight but is hydrophilic where may it distribute?
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it can move through the endothelial slit junctions of the capillaries into interstitial fluid; however, hydrophilic drugs cannot move across membranes of cells to enter the water phase inside of the cell. These drugs distribute into volume which is sum of plasma water and interstitial fluid, which together constitute extracellular fluid.
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what are class I drugs?
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dose is less than available binding sites
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what are class II drugs?
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dose is greater than available binding sites
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in first order kinetics what is the relationship between the rate of drug metabolism and concentration of free drug?
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rate of drug metabolism is directly proportional to concentration of free drug; a constant fraction of drug is metabolized per unit of time
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what is zero order kinetics?
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enzyme is saturated by a high free-drug concentration and the rate of metabolism remains constant over time; a constant amount of drug is metabolized per unit time
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what are phase I reactions?
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CYP450 enzymes: oxidation, reduction, and/or hydrolysis
Convert to lipophilic molecules into more polar molecules by introducing or unmasking a polar functional group |
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what are phase II reactions?
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conjugation reactions: usually results in more polar, usually more water-soluble compounds that are therapeutically inactive
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CYP2C9 SUBSTRATES:
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warfarin
phenytoin ibuprofen tolbutamide |
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CYP2C9/10 INDUCERS:
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phenobarbital
rifampin |
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CYP2D6 SUBSTRATES:
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desipramine
imipramine haloperiodol propanolol |
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CYP3A4/5 SUBSTRATES:
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carbamazepine
cyclosporine erythromycin nifedipine verapamil |
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CYP3A4 INDUCERS:
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carbamazepine
dexamethasone phenobarbital phenytoin rifampin |
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glomerular filtration rate is usually what percentage of renal plasma flow?
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glomerular filtration rate is usually 20% of renal plasma flow
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how many half-lives does it take to get to steady state?
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about 3.3 half-lives
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