Pharmacology Questions and Answers Part-4

1. A prodrug is:
a) The prototype member of a class of drugs
b) The oldest member of a class of drugs
c) An inactive drug that is transformed in the body to an active metabolite
d) A drug that is stored in body tissues and is then gradually released in the circulation

Answer: c

2. Which of the following cytochrome P450 isoenzymes is involved in the metabolism of largest number of drugs in human beings and has been implicated in some dangerous drug interactions:
a) CYP 3A4
b) CYP 2C9
c) CYP 2E1
d) CYP 1A2

Answer: a

3. The following is not true of the cytochrome P450 isoenzyme CYP2D6:
a) It generates the hepatotoxic metabolite N-acetyl benzoquinone immine from paracetamol
b) It is involved in demethylation of codeine into morphine
c) Its altered form is responsible for poor capacity to hydroxylate many drugs including metoprolol
d) It is inhibited by quinidine

Answer: a

4. The most commonly occurring conjugation reaction for drugs and their metabolites is:
a) Glucuronidation
b) Acetylation
c) Methylation
d) Glutathione conjugation

Answer: a

5. Microsomal enzyme induction can be a cause of:
a) Tolerance
b) Physical dependence
c) Psychological dependence
d) Idiosyncrasy

Answer: a

6. The following drug metabolizing reaction is entirely nonmicrosomal:
a) Glucuronide conjugation
b) Acetylation
c) Oxidation
d) Reduction

Answer: b

7. Which of the following types of drug metabolizing enzymes are inducible:
a) Microsomal enzymes
b) Nonmicrosomal enzymes
c) Both microsomal and nonmicrosomal enzymes
d) Mitochondrial enzymes

Answer: a

8. Induction of drug metabolizing enzymes involves:
a) A conformational change in the enzyme protein to favour binding of substrate molecules
b) Expression of enzyme molecules on the surface of hepatocytes
c) Enhanced transport of substrate molecules into hepatocytes
d) Increased synthesis of enzyme protein

Answer: d

9. Select the drug that undergoes extensive first-pass metabolism in the liver:
a) Phenobarbitone
b) Propranolol
c) Phenylbutazone
d) Theophylline

Answer: b

10. Drugs which undergo high degree of first-pass metabolism in
a) Have low oral bioavailability
b) Are excreted primarily in bile
c) Are contraindicated in liver disease
d) Exhibit zero order kinetics of elimination

Answer: a