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14 Cards in this Set

  • Front
  • Back
What are the 4 components of pharmacokinetics?
1. Absorption
2. Distribution
3. Metabolism/biotransformation
4. Excretion
What is bioavailability?
amount of the drug reaching the blood stream or systemic circulation
About what porportion of orally administered medication is actually absorbed in the bloodstream? What about injected drugs?
30-60%; 100%
What are the two phases of distribution in pharmacokinetics?
1. Distribution to organs with a rich blood supply
2. Distribution to tissues with less extensive circulation, e.g. muscles and fat
______-soluble drugs have an easier time crossing the blood-brain barrier
fat soluble
Which family of enzymes is responsible for breaking down most psychotropic meds?
CYP 450 (cytochrome P450)
What is a substrate (in the context of drug metabolism)?
a substance broken down by a specific enzyme; e.g. diazepam is a substrate for the CYP 450 enzyme 2C19
What happens when a person ingests both a subsrate and an inhibitor for the same enzyme?
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
Name one substrate and one inhibitor of the P450 enzyme 2C19
substrate: diazepam/Valium
inhibitor: fluoxetine/Prozac
Name one substrate and one inhibitor of the P450 enzyme 2D6
substrate: haloperidol/Haldol
inhibitor: sertraline/Zoloft
Which organ is responsible for most drug excretion?
Kidneys - excretion via urination
How can drugs be excreted, other than via urination?
respiration, sweating, bowel movements
What is a half-life of a drug?
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
What does it mean when a drug has reached a "steady state?"
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