Chapter – 3 Drug Metabolism
1. Biotransformation of drugs is defined as the conversion from one physical form to another.
A. True
B. False
Ans. B
(Explanation: Biotransformation of drugs is the conversion of drugs from one chemical form to another. The term is used with metabolism. The chemical changes are usually affected by enzymatically in the body. For example conversion of penicillin to penicilloic acid by bacterial penicillinase.)
2. The drug biotransformation is a detoxification process.
A. True
B. False
Ans. A
3. Phase 1 reactions are also known as a synthetic reaction.
A. True
B. False
Ans. A
(Explanation: Phase I reactions include introducing or removing of –OH, -COOH, -NH2 and –SH. This phase I reactions are also known as functionalization reactions. These transformations are also known as a synthetic reaction.)
4. The phase I reactions are detoxification pathways.
A. True
B. False
Ans. A
5. The phase II reactions are detoxification pathways.
A. True
B. False
Ans. A
6. Following are the Phase I reactions except ____________
A. Oxidative reactions
B. Hydrolytic reactions
C. Reductive reactions
D. Sulphide reactions
Ans. D
7. Which of the following statements is the closest description of Phase I metabolism?
A. Reactions which add a polar molecule to a functional group already present on a drug
or one of its metabolites
B. Reactions which occur in the blood supply.
C. Reactions which add a polar functional group to a drug.
D. Reactions which occur in the gut wall.
Ans. C
8. Which of the following statements is the closest description of Phase II metabolism?
A. Reactions which add a polar molecule to a functional group already present on a drug
or one of its metabolites.
B. Reactions which occur in the blood supply.
C. Reactions which add a polar functional group to a drug.
D. Reactions which occur in the gut wall.
Ans. A
9. Which of the following is not a characteristic of the moieties that are transferred to the substrate in phase II reactions?
A. Simple endogenous molecules are transferred
B. Large molecular sized groups are attached
C. Strong polar groups are attached
D. Strong nonpolar groups are attached
Ans. D
10. Which of the following enzymes is not involved in catalyzing Phase I metabolic reaction?
A. Flavin-containing monooxygenases
B. Oxidation of alkyl groups
C. Glucuronyl transferase
D. Esterases
Ans. C
11. Which of the following reactions is not a Phase I metabolic transformation?
A. Reduction of ketones
B. Conjugation to alcohols
C. Monoamine oxidases
D. Esterhydrolysis
Ans. B
12. What is the major end product of oxidation of aromatic carbon atoms?
A. Arenols
B. Catechol
C. Glutathione
D. Arene oxide
Ans. A
13. Which of the following is not a common N containing functional groups which undergo reduction reactions?
A. Nitro compounds
B. Azo compounds
C. N-oxide compounds
D. Nitrite compounds
Ans. D
14. What does the hydrolysis of Aspirin yield us with?
A. Salicylic acid only
B. Salicylic acid and CH3COOH
C. CH3COOH
D. Succinic acid
Ans. B
15. Which enzyme is important in the Phase II reactions?
A. Esterase
B. Amidases
C. Transferase
D. Aldo-keto-reductases
Ans. C
16. Which of the following groups is least susceptible to cytochrome P450 enzymes?
A. Terminal methyl groups
B. Epoxide group
C. Benzylic carbon atoms
D. Quaternary carbon atoms
Ans. D
17. Alkenes and aromatic groups can be metabolised to diols. Which enzymes are involved?
A. cytochrome P450 enzymes
B. epoxide hydrolase
C. both of the above
D. neither of the above
Ans. C
18. Solubility of a drug in polar solvents and Non-polar solvents depends upon-
A. Chemical structure
B. Particle size
C. Crystal form
D. All of above
Ans. D
19. Higher will be the diffusion of the drug across the membrane if-
A. Higher value of partition-coefficient
B. Low value of partition-coefficient
C. Higher water soluble
D. None of above
Ans. A
20. Diazepam gets metabolised into Hydroxydiazepam is example of-
A. Oxidation at allylic carbon atom
B. Oxidation at the carbon alpha to carbonyl and imino group
C. Oxidation at benzylic carbon atom
D. Aromatic and Side chain Hydroxylation
Ans. B
21. __________reaction is most common in drugs having ester or amide functional groups
A. Oxidative reactions
B. Reduction
C. Hydrolysis
D. Phase I
Ans. C
22. UDPGA means….
A. Urane diphospho -a- D glucuronic acid
B. Uridine diphospho -a- D glucuronic acid
C. Uridine diphospho-D glucuronic acid
D. Uric diphospho -a- D glucuronic acid
Ans. B
23. Which of the following statement is false?
A. D-glucuronic acid is easily available
B. Several functional groups can be easily linked with the D-glucuronic acid
C. Conjugation with D-glucuronic acid occurs to a high degree
D. Whole animal kingdom have the common ability to produce D-glucuronic acid
Ans. D
24. Which enzyme is of the utmost importance for the 2nd step in the formation of Glucuronide?
A. Esterase
B. Amidases
C. Transferase
D. UDP-glucuronyl transferase
Ans. D
25. What is the site of first-pass metabolism before molecules reach systemic circulation?
A. Kidney
B. Throat
C. Liver
D. Intestine
Ans. D
26. What plays a major role in extra-hepatic metabolism and contains CYP3A4 isozyme and P-glycoprotein?
A. Kidney
B. Throat
C. Liver
D. Intestine
Ans. C
27. What test uses microsomal extracts from the ER for in-vitro drug metabolism studies?
A. Ames test
B. Biochemical tests
C. Serology
D. Polymorphisms
Ans. A
28. Which of the following are protein components of the cytochrome P450 system?
A. Heme protein CYP450
B. NADH-CYP450 reductase
C. NADPH-CYP450 reductase
D. A and B E. A and C
Ans. A
29. Which of the following statements is not true about cytochrome P450 enzymes?
A. They contain haem and magnesium.
B. They belong to a general class of enzymes called monooxygenases.
C. There are over 30 different cytochrome P450 enzymes.
D. Variation in cytochrome P450 enzyme profile between individuals can explain
individual variation in drug susceptibility.
Ans. A
30. What is not a xenobiotic?
A. Plant toxins
B. Drugs
C. Steroids
D. Environmental pollutants
Ans. C
31. What cytochrome P450 isozyme is most abundantly expressed in the human liver and intestines?
A. CYP1A1
B. CYP3A4
C. CYP2C9
D. CYP2D6
Ans. B
32. Which of the following is an antiarrhythmic drug that is a calcium channel blocker?
A. Lidocaine
B. Nitroglycerin
C. Nifedipine
D. Codeine
Ans. C
33. What drug should not be given to a patient that is a poor CYP2D6 metabolizer?
A. Codeine
B. Lidocaine
C. Nifedipine
D. Nitroglycerin
Ans. A
34. What injection is administered directly into systemic circulation causing rapid distribution?
A. Intramuscular
B. Intravenous
C. Intracerebral
D. Intraspinal
Ans. B
35. Where is Protonsil converted to Sulfanilamide?
A. Liver
B. Gut
C. Kidney
D. Colon
Ans. B
36. What are xenobiotics?
A. Another form of antibiotics
B. A form of nutrient
C. Nutrients which kill the gut harmful microbes
D. Anything that is not nutrients and enters the body through different routes
Ans. D
37. What is the active form of salicylic acid?
A. Sialic acid
B. Salic acid
C. Salicylic acid
D. Salicycle acid
Ans. C
38. What is the inactive form of Codeine?
a. Codene
b. Codane
c. Morphine
d. Poppy
Ans. C
39. Which of the following is the correct decreasing order of drug metabolism?
A. Liver > lungs > kidneys > intestine > placenta > skin > adrenals
B. Liver > lungs > kidneys > intestine > adrenals > placenta > skin
C. Liver > kidneys > lungs > intestine > placenta > adrenals > skin
D. Liver > lungs > intestine > kidneys > placenta > adrenals > skin
Ans. A
40. Which one of the following is reactive and a known carcinogenic?
A. Cytochrome P-450
B. Catechol
C. Glutathione
D. Arene oxide
Ans. D
41. Which of the following is not an example of a drug undergoing acetylation reaction?
A. Hydrazine
B. Salicylic acids
C. Sulphonamides
D. Histamines
Ans. B
42. The overall rate of biotransformation is higher in neonates and infants than in adults.
A. True
B. False
Ans. B
43. In comparison with children and young adults, elderly adults tend to have a reduced capacity to metabolize drugs.
A. True
B. False
Ans. A
44. What is enzyme induction?
A. The phenomenon of increased drug metabolizing ability of enzymes by drugs and chemicals
B. The phenomenon of increasing drug bioavailability drugs and chemicals
C. The phenomenon of increasing drug distribution drugs and chemicals
D. The phenomenon of increasing drug concentration for a particular tissue by drugs and chemicals
Ans. A
Explanation: The phenomenon of increased drug metabolizing ability of enzymes by drugs and chemicals is called as enzyme induction and the agents which helps to bring such changes are known as inducers.
45. Which of the following drugs has self -induction to stimulate their own metabolism?
A. Cortisol
B. Pentobarbital
C. Meprobamate
D. Contraceptives
Ans. C
Explanation: Drugs such as carbamazepine, Meprobamate, cyclophosphamide, rifampicin, etc. stimulate their own metabolism. This phenomenon is known as auto-induction or self – induction.
46. Alcohol is the inducer for which drug?
A. Cortisol
B. Pentobarbital
C. Meprobamate
D. Oral contraceptives
Ans. B
Explanation: Alcohol act as an inducer for pentobarbital, coumarins, and phenytoin. Meprobamate is self-inducing. Oral contraceptives are induced by barbiturates.
47. What is the name of the process where structurally same compounds compete for the same site on an enzyme to inhibit that?
A. Altered physiology
B. Repression
C. Non-competitive inhibition
D. Competitive inhibition
Ans. D
Explanation: Competitive inhibition results when structurally similar compounds compete for the same site on an enzyme. Such an inhibition due to substrate competition is reversible and can be overcome by a high concentration of one substrate. Methacholine inhibits the metabolism of acetylcholine by competing with it for cholinesterase.
48. What is the name of the process where structurally different compounds interact with the enzyme and prevent the metabolism of the drug?
A. Altered physiology
B. Repression
C. Non-competitive inhibition
D. Competitive inhibition
Ans. C
Explanation: Non-competitive inhibition happens when structurally different compounds interact with the enzyme and prevent the metabolism of the drug. This interaction is not structured specifically. So lead, mercury, arsenic, organophosphorus insecticides inhibit
enzymes noncompetitively.
49. What is the name of the process where the enzyme amount is decreases due to a decrease in enzyme synthesis?
A. Altered physiology
B. Repression
C. Non-competitive inhibition
D. Competitive inhibition
Ans. B
Explanation: Repression is the process where the enzyme amount is decreases due to a decrease in enzyme synthesis. The synthesis of the enzyme can be affected by puromycin and actinomycin D. It can also happen by raising the rate of enzyme degradation such as carbon tetrachloride, carbon disulphide, disulfiram, etc.
50. What is the name of the process where due to nutritional deficiency an enzyme content is decreased?
A. Altered physiology
B. Repression
C. Non-competitive inhibition
D. Competitive inhibition
Ans. A
Explanation: Altered physiology is the process where due to nutritional deficiency an enzyme content is decreased. Thus decreasing the enzyme content, and decreasing the drug metabolizing time.
51. Which one of the following is not an environmental agent to decrease drug metabolizing ability?
A. DDT
B. Cigarette smoke
C. Organophosphate insecticides
D. Methacholine
Ans. D
Explanation: Methacholine inhibits the metabolism of acetylcholine by competing with it for cholinesterase. It is not an environmental factor. Halogenated pesticides e.g. DDT, polycyclic aromatic hydrocarbon e.g. cigarette smoke, organophosphate insecticides, heavy metals inhibit drug metabolizing of enzymes.
52. What is polygenic control of drugs?
A. Drug controlling seen in an individual
B. Drug controlling seen in twins
C. Drug controlling seen in between different species
D. Drug controlling seen in a particular population
Ans. B
Explanation: Polygenic control has been observed in twins. In identical twins that are monozygotic twins, there is very little or no difference in drug metabolism. It was detected that there was no difference in the metabolism of phenylbutazone, dicoumarol, and antipyrine. Although large variations were detected in dizygotic twins.
53. Differences observed in metabolism of drug among different races is known as
A. Pharmacogenetics
B. Ethnic variations
C. Discontinues variation
D. Polygenic control
Ans. B
Explanation: Differences observed in the metabolism of the drug among different races is known as ethnic variation. Polygenic control is the control of drug metabolizing in thetwins. Pharmacogenetics is the study of inter-subject variability in drug response.
54. Which age group is known as the neonates?
A. Up to 2 months
B. Up to 2 years
C. Up to 6 months
D. Up to 1 year
Ans. A
Explanation: Babies below the age of 2 months are called as neonates. Their microsomal enzymes are not fully developed. Thus takes much longer time to metabolize drugs.
55. Which age group metabolizes drugs faster than the adults?
A. Between 1-12 year
B. Between 1-15 year
C. Between 6-12 year
D. Between 12-18 year
Ans. A
Explanation: Children and older infant of the age group 1-12 year metabolize several drugs much more rapidly than adults. The rate of metabolism reaches a maximum somewhere between 6 months to 12 years of age. As a result, they require large mg/kg doses in comparison to adults.
56. Fat-free diet depresses cytochrome P-450 level.
A. True
B. False
Ans. A
Explanation: A fat-free diet decreases the phospholipid content. Phospholipids are important components of microsomes. When these become deficient, the cytochrome p-450 levels decrease.
57. Maternal drug metabolizing ability increases in the later stage of pregnancy.
A. True
B. False
Ans. B
Explanation: Maternal drug metabolizing ability decreases in the later stage of pregnancy. Due to high levels of steroid hormones in circulation during pregnancy, in women, the metabolism of promazine and pethidine decreases. Thus, maternal drug metabolizing ability decreases.
58. Enzyme activity is maximum during the early morning.
A. True
B. False
Ans. A
Explanation: By research, it has been observed that the enzyme activity is maximum during the early morning and minimum during the late afternoon. This also corresponds to high and low serum levels of corticosterone.
59 Intermediate of aromatic hydroxylation is
A. Arene
B. Epoxide
C. Aldehyde
D. Ketone
Ans.B
60 Oxidation of Propranolol results in
A. 2-hydroxy propranolol
B. 3-hydroxy propranolol
C. 4-hydroxy propranolol
D. 2,2-Dihydroxy propranolol
Ans. C
61 Oxidation of olefin results in
A. Aldehyde
B. Ketone
C. Diol
D. Carboxylic acid
Ans. C
62 Oxidation of Tolbutamide is the example of
A. Oxidation of Olefin
B. Oxidation of Aliphatic carbon
C. Oxidation of Benzylic carbon
D. Oxidation of Allylic carbon
Ans. C
63 Carbon atom adjacent to olefinic double bond is known as
A. Alicyclic carbon
B. Aliphatic carbon
C. Benzylic carbon
D. Allylic carbon
Ans. D
64 Oxidation of Hexobarbital results in
A. 2-hydroxy Hexobarbital
B. 3-hydroxy Hexobarbital
C. 4-hydroxy Hexobarbital
D. 2,3-Dihydroxy Hexobarbital
Ans. B
65 Given reaction is the example of_________
A. Oxidation of Carbon atom alpha to Carbonyl and Imine
B. Oxidation of Aliphatic carbon
C. Oxidation of Benzylic carbon
D. Oxidation of Allylic carbon
Ans. A
66 ω – oxidation of Valproic acid results in
A. 2-hydroxy valproic acid
B. 3-hydroxy valproic acid
C. 4-hydroxy valproic acid
D. 5-hydroxy valproic acid
Ans. D
67 ω1 – oxidation of Valproic acid results in
A. 2-hydroxy valproic acid
B. 3-hydroxy valproic acid
C. 4-hydroxy valproic acid
D. 5-hydroxy valproic acid
Ans. C
68 Given reaction is the example of_________
A. Oxidation of Alicyclic carbon
B. Oxidation of Aliphatic carbon
C. Oxidation of Benzylic carbon
D. Oxidation of Allylic carbon
Ans. A
69 Desulphuration of given drug results in _______
A. Phenobarbitone
B. Paroxon
C. Sulphanilamide
D. PABA
Ans. A
Explanation:
70 Reduction of given drug results in______
A. Paroxon
B. Sulphanilamide
C. PABA
D. 7 – aminometabolite
Ans. D
Explanation:
A. Oxidation
B. Reduction
C. Hydrolysis
D. Conjugation
Ans. C
73 By Glycine conjugation Benzoic acid results in
A. Salicylic acid
B. Oxalic acid
C. Hippuric acid
D. Carbamic acid
Ans. C
74 The enzymes are divided into two categories, these are _______ and ______
A. Acidic drug metabolizing and basic drug metabolizing
B. Present in the liver and not present in the liver
C. Microsomal and non-microsomal
D. There is no such division
Ans. C
Subject:- Medicinal chemistry MCQs with Answer
Topic:- Drug metabolism (unit:- 3 MCQs
