Medical Pharmacology: Pharmacodynamics Practice Questions
Choose the correct answer for each question.
Concerning locations for drug metabolism: which one(s) of the following statements/statements is/are correct?
Highest levels of xenobiotic (substances not found in the body, i.e. foreign substances including drugs) metabolizing enzymes are found in the G.I. tract.
Drugs that enter the portal circulation prior to entering systemic circulation may be subject to first pass effects.
Both
Neither
Drugs which are poorly metabolized exhibit:
Longer elimination half-lives
Remain in the body for more extended periods of time
Both
Neither
Primary localization of phase I cytochrome P450 drug metabolizing isoforms, flavin containing monooxygenases, and epoxide hydrolases (EHs):
Cell plasma membrane
Mitochondrial membrane
Endoplasmic reticulum
Nuclear membrane
Drugs hydrolyzed by phase I enzymes and subsequently conjugated by a phase II UDP glucuronosyltransferase (UGT) are localized in the endoplasmic reticulum during these processes.
True
False
Example/examples of drug metabolizing cytosolic transferase(s):
Glutathione-S-transferase
Uridine diphosphate-glucuronosyltransferase
Sulfotransferase
A & B
B & C
A & C
A, B & C
Concerning the cytochrome P450 superfamily:
Each enzyme contains a heme molecule noncovalently attached to a polypeptide chain.
If cytochrome P450-mediated metabolism involves the consumption of at least one oxygen molecule and produces both water and oxidized substrate.
Both
Neither
Concerning cytochrome P450:
This system is involved in bile acid production from cholesterol.
In distinction from drug-metabolizing cytochrome P450 isoforms, cytochrome P450 forms metabolizing bile acid synthesis and steroid synthesis show very specific substrate specificity.
Coadministering two drugs both metabolized by the same cytochrome p450 isoform may result in inhibition of the metabolism of one or both agents, causing higher drug plasma levels.
True
False
Only a few cytochrome p450 isoforms metabolize most drugs.
