Medical Pharmacology Chapter 3: Pharmacodynamics Practice Questions

Concerning administration of the statin along with a macrolide antibiotic: which one(s) of the following is/are correct?
1. These agents are likely metabolized by the same cytochrome p450 isoform.
2. These drugs may exhibit drug interactions as a result of their biotransformation pathways.
3. Both
4. Neither
Concerning cytochrome p450 isoforms:
1. Antifungal drug ketoconazole inhibits CYP3A4 and other cytochrome p450 isoforms.
2. Combination of ketoconazole administered with anti-HIV viral protease inhibitors may result in reduced anti-HIV drug clearance given cytochrome p450 isoform inhibition by ketoconazole.
3. Both
4. Neither
Concerning terfenadine and drug-drug interactions:
1. Terfenadine (antihistamine) is a prodrug activated by CYP3A4, a cytochrome p450 isoform, via oxidative metabolism
2. In the presence of a CYP3A4 inhibitor i.e. erythromycin (and grapefruit juice), the prodrug terfenadine serum levels increase.
3. Terfenadine, at higher concentrations, is proarrhythmic, potentially causing serious cardiac arrhythmias.
4. A & B
5. B & C
6. A & C
7. A, B & C
Cytochrome p450 isoforms exhibit polymorphisms, which account for some differences in drug metabolism between individuals. Which one(s) of the following is/are
1. CYP2D6 polymorphism resulted in removal of some clinically used agents.
2. CYP2D6 polymorphism is resulted in the warning of cautious use for some drugs.
3. Both
4. Neither
Flavin-containing monooxygenases (FMOs) represent another group (superfamily) of phase I enzymes.
1. FMOs are expressed at relatively low levels in the liver but at high levels in the kidney.
2. FMOs are found bound to the endoplasmic reticulum which facilitates metabolism of hydrophobic drugs.
3. Both
4. Neither
Concerning Flavin-containing monooxygenases:
1. FMOs are comparable in importance to cytochrome p450 isoforms with respect to drug metabolism.
2. FMOs are more likely to convert the parent compound into metabolites that are usually more toxic than the parent compound.
3. Both
4. Neither
Epoxide metabolites of drugs occurring as a result of actions by cytochrome p450 isoforms can be hydrolyzed by epoxide hydrolases found in cytosol or associated with endoplasmic reticulum membranes.
1. True
2. False
Carbamazepine, an antiepileptic prodrug, is converted by a cytochrome p450 isoform to an active epoxide derivative. The metabolite, which can exhibit toxicity, is itself hydrolyzed to a dihydrodiol by membrane-bound epoxide hydrolase. Inhibition of epoxide hydrolase by valproate, for example, would likely result in clinically important drug interactions with carbamazepine.
1. True
2. False
Concerning carboxylesterases:
1. These enzymes represent a superfamily that catalyze both amide- and ester hydrolysis.
2. Irinotecan, an anticancer prodrug, is activated by carboxylesterases to the active topoisomerase inhibitor form.
3. Both
4. Neither
Inhibitors of the soluble epoxide hydrolase form appear effective in decreasing neuropathic pain and pain associated with inflammation.
1. True
2. False