Medical Pharmacology: Drug Metabolism Practice Questions
Choose the correct answer for each question.
Genetic polymorphism describes multiple variant forms of a particular DNA sequence associated with different individuals or populations.
True
False
Expression of cytochrome P450 isoforms:
May vary due to dietary exposure to enzyme inducers
May vary due to interindividual hereditary differences in cytochrome P450 structures.
Both
Neither
Prominent cytochrome P450(s) enzymes involved in drug metabolism include this/these subfamily/subfamilies:
CYP2C
CYP2D
CYP3A
A & B
A & C
C only
A, B & C
CYP3A4 Cytochrome P450 isoform:
This isoform is the one that is most abundantly expressed in liver.
Involved in metabolism of over half of the clinically used drugs.
Both
Neither
One consequence of human CYP gene polymorphism
(and differences in gene regulation) is substantial interindividual
variability in CYP expression.
True
False
Human CYP gene(s) that show genetic polymorphism:
CYP2A6
CYP2D6
CYP2C19
All of the above cytochrome P450 isoforms exhibit genetic polymorphism
Ethnic differences in drug metabolism often results from genetic polymorphisms in cytochrome P450 isoforms.
True
False
Cytochrome P450 isoforms and genetic polymorphism:
About 20% of Asians do not express CYP2C19.
CYP2D6 polymorphism resulted in withdrawal of some clinically used drugs
including debrisoquine, an antihypertensive drug comparable to guanethidine.
Both
Either
CYP2D6 polymorphism requires cautious use of certain drugs which are substrates for this isoform. These drugs that require cautious use include certain antiarrhythmic agents such as flecanide and encainide, some antidepressant medications such as nortriptyline and desipramine, both first-generation agents, and codeine.
True
False
Patients lacking CYP2D6 cytochrome P450 isoform activity may exhibit limited analgesic effects upon codeine administration, since the CYP2D6 catalyzed conversion of codeine to morphine does not occur.
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Source Material:
Buxton ILO Chapter
2: Pharmcokinetics: The Dynamics of Drug Absorption,
Distribution, Metabolism, and Elimiation in Goodman & Gilman's:
The Pharmacological Basis of Therapeutics, 14e, (Brunton LL H
Knollmann BC, eds) McGraw-Hill Education, 2023.
Gonzalez FJ
Coughtrie M Chapter 5: Drug Metabolism in Goodman & Gilman's:
The Pharmacological Basis of Therapeutics, 14e, (Brunton LL H
Knollmann BC, eds) McGraw-Hill Education, 2023.
Holford NHG Chapter
3: Pharmacokinetics & Pharmacodynamics: Rational Dosing &
the Time Course of Drug Action: in Basic & Clinical
Pharmacology (Katzung BG, Editor; Vanderah TW, Associate
editor) 15e McGraw Hill 2021.
Correia MA Chapter 4
Drug Biotransformation in Basic &
Clinical Pharmacology (Katzung BG, Editor; Vanderah TW, Associate
editor) 15e McGraw Hill 2021.
Baca QJ Golan DE
Pharmacokinetics Chapter 3: Principles of Pharmacology:
The Pathophysiologic Basis of Drug Therapy. (Golan DE, editor-in
chief, Armstrong EJ Armstrong AW, associate editors) 4e Wolters
Kluwer 2017.
Guengerich FP
Chapter 4: Drug Metabolism in
Principles of Pharmacology: The Pathophysiologic Basis of Drug Therapy. (Golan DE, editor-in
chief, Armstrong EJ Armstrong AW, associate editors) 4e Wolters
Kluwer 2017.
Flood P Shafer SL
Chapter 2 Basic Principles of Pharmacology in Stoelting's
Pharmacology & Physiology in Anesthetic Practice (Glood P
Rathmell JP Urman RD, eds) 6e Wolters Kluwer 2022.
Burchum JR Rosenthal
LD Lehne's Pharmacology for Nursing Care Unit II Chapter 4
Pharmcokinetics 11 e Elsevier 2022.
