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14 Cards in this Set
- Front
- Back
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What are the 4 components of pharmacokinetics?
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1. Absorption
2. Distribution 3. Metabolism/biotransformation 4. Excretion |
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What is bioavailability?
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amount of the drug reaching the blood stream or systemic circulation
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About what porportion of orally administered medication is actually absorbed in the bloodstream? What about injected drugs?
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30-60%; 100%
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What are the two phases of distribution in pharmacokinetics?
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1. Distribution to organs with a rich blood supply
2. Distribution to tissues with less extensive circulation, e.g. muscles and fat |
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______-soluble drugs have an easier time crossing the blood-brain barrier
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fat soluble
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Which family of enzymes is responsible for breaking down most psychotropic meds?
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CYP 450 (cytochrome P450)
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What is a substrate (in the context of drug metabolism)?
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a substance broken down by a specific enzyme; e.g. diazepam is a substrate for the CYP 450 enzyme 2C19
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What happens when a person ingests both a subsrate and an inhibitor for the same enzyme?
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The inhibitor stops the enzyme from breaking down the substrate, resulting in higher levels of the substrate - with a medication, the person may end up with too much in his or her system
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Name one substrate and one inhibitor of the P450 enzyme 2C19
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substrate: diazepam/Valium
inhibitor: fluoxetine/Prozac |
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Name one substrate and one inhibitor of the P450 enzyme 2D6
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substrate: haloperidol/Haldol
inhibitor: sertraline/Zoloft |
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Which organ is responsible for most drug excretion?
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Kidneys - excretion via urination
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How can drugs be excreted, other than via urination?
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respiration, sweating, bowel movements
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What is a half-life of a drug?
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the amount of time it takes for the serum concentration of a drug to be reduced from maximum to 50%; half-life influences dosage amounts and timing
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What does it mean when a drug has reached a "steady state?"
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Levels of the drug in the bloodstream have reached a point where the amount ingested is equal to the amount excreted; 4-5 half-lives/doses for most drugs
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