Mcqs on CNS pharmacology with keys and explanation

 

1. A-50-year-old man has a history of frequent episodes of renal colic with high- calcium renal stones. The most useful agent in the treatment of recurrent calcium stones is

(a) Mannitol

(b) Furosemide

(c) Spironolactone

(d) Hydrochlorothiazide

(e) Acetazolamide

2. Which of the following drugs is correctly associated with its site of action and maximal diuretic efficacy?

(a) Thiazides–distal convoluted tubute–10% of filtered Na+

(b) Spironolactone–proximal convoluted tubule –40%

(c) Bumetanide–thick ascending limb–15%

(d) Metolazone–collecting tubule–2%

(e) All of the above

3. Substance secreted into the blood by a neuron is

(a) Neurohormone

 (b) Neuromodulator

(c) Neuromediator

(d) Neurotransmitter

4. Which of the following is a leukotriene receptor blocker?

(a) Alprostadil

(b) Aspirin

(c) Ibuprofen

(d) LTC4

(e) Zafirlukast

5. A molecule that stimulates nitric oxide synthase, especially the eNOS isoform, is

 

(a) Acetylcholine

(b) Citruline

(c) Isoproterenol

(d) Nitroglycerin

(e) Nitroprusside

6. The primary endogenous substrate for nitric oxide synthase is

(a) Acetylcholine

(b) Angiotensinogen

(c) Arginine

(d) Citruline

(e) Heme

7. Which of the following is a recognizedeffect of nitric oxide?

(a) Arrhythmia

(b) Bronchoconstriction

(c) Constipation

(d) Inhibition of acute graft rejection

(e) Pulmonary vasodilation

8. cAMP is an example of

(a) Neurohormone

(b) Neuromodulator

(c) Neuromediator

(d) Neurotransmitter

9. One effect that theophylline, nitroglycerin, isoproterenol, and histamine have in common is

(a) Direct stimulation of cardiac contractile force

(b) Tachycardia

(c) Increased gastric acid secretion

(d) Postural hypotension

(e) Throbbing headache

10. Which one of the following chemicals does not satisfy the criteria for a neurotransmitter role in the CNS?

(a) Acetylcholine

(b) Dopamine

(c) Glycine

(d) Nitric Oxide

(e) Substance P

11. Neurotransmitters may

(a) Increase chloride conductance to cause  inhibition

(b) Increase potassium conductance to cause excitation

(c) Increse sodium conductance to cause inhibition

(d) Increase calcium conductance to cause inhibition

(e) Exert all of the above actions

>12. Which of the following chemicals is most likely to function as a neurotransmitter in hierarchical systems?

(a) Dopamine

(b) Glutamate

(c) Metenkephalin

(d) Norepinephrine

(e) Serotonin

13. Activation of metabotropic receptors located presynaptically causes inhibition by decreasing the inward flux of

(a) Calcium

(b) Chloride

(c) Potassium

(d) Sodium

(e) None of the above

14. This compound decrease the functional activities of several CNS neurotransmit- ters, including dopamine, norepineph- rine, and serotonin. At high doses it may cause parkinsonism-like extrapyramidal system dysfunction.

(a) Amphetamine

(b) Baclofen

(c) Diazepam

(d) Ketamine

(e) Reserpine

15. This amine neurotransmitter is found in high concentration in cell bodies in the pons and brain stem; at some sites, release of transmitter is autoregulated via presynaptic inhibition.

(a) Acetylcholine

(b) Dopamine

(c) Glutamate

(d) Norepinephrine

(e) Substance P

 

16. Suramin is an antagonists of ________ receptors

(a) Purine

(b) Somatostanin

(c) Neuropeptide Y

(d) Neurotensin

17. Which one of the following statements best describes the mechanism of action of benzodiazepines?

(a) Benzodiazepines activate GABAB receptors in the spinal cord

(b) Their inhibition of GABA transminase leads to increased levels of GABA

(c) Benzodiazepines block glutamate receptors in hierarchical neuronal pathways in the brain

(d) They increase the frequency of opening of chloride ion channels that are coupled to GABAA receptors

(e) They are direct-acting GABA receptor agonists in the CNS

18. Which one of the following statements about the use of triazolam in this elderly patient is accurate?

(a) Ambulatory dysfunction does not occur in elderly patients taking one-half of the conventional adult dose

(b) Hypertension is a common adverse effects of benzodiazepines in patients over 70 years of age

(c) Over-the-counter cold medications may antagonize the hypnotic effects of the drug

(d) She may experience amnesia, especially if she also drinks alcoholic beverages

(e) Triazolam is distinctive in that it does not cause rebound insomnia on abrupt

discontinuance

19. The most likely explanation for the increased sensitivity of elderly patients to a single dose of triazolam and other sedative-hypnotic drugs is

(a) Changes in brain function that accompany the aging process

(b) Decreased renal function

(c) Increased cerebral blood flow

(d) Decreased hepatic metabolism of lipid- soluble drugs

(e) Changes in plasma protein binding

20. Induction of various forms of synaptic plasticity is more closely associated with______ receptors

(a) AMPA

(b) Kainate

(c) NMDA

(d) All of the above

21. Which one of the following drugs may increase anticoagulant effects by displacement of warfarin from plasma protein binding sites and is inactive until converted in the body to an active metabolite?

(a) Buspirone

(b) Chloral hydrate

(c) Clorazepate

(d) Secobarbital

(e) Zaleplon

22. Which one of the following drugs has been used in the management of alcohol withdrawal states and in maintenance treatment of patient with tonic-clonic or partial seizure states? Its chronic use may lead to an increased metabolism of warfarin and phenytoin.

(a) Chlordiazepoxide

(b) Meprobamate

(c) Phenobarbital

(d) Triazolam

(e) Zolpidem

23. A 40-year-old patient with liver dysfunction is scheduled for a surgical procedure. Lorazepam can be used for preanesthetic sedation in this patient without concern for excessive CNS depression because the drug is

(a) A selective anxiolytic like buspirone

(b) Actively secreted in the renal proximal tubule

(c) Conjugated extrahepatically

(d) Eliminated via the lungs

(e) Reversible by administration of naloxone

24. This hypnotic drug facilitates the inhibitory actions of GABA, but it lacks anticonvulsant or muscle relaxing properties and has minimal effect on sleep architecture.

(a) Buspirone

(b) Diazepam

(c) Flurazepam

 (d) Phenobarbital

(e) Zaleplon

25. The most frequent type of drug interaction that occurs in patients using drugs of the sedative hypnotic class is

(a) Additive CNS depression

(b) Antagonism of sedative or hypnotic actions

(c) Competition for plasma protein binding

(d) Induction of liver drug-metabolizing enzymes

(e) Inhibition of liver drug-metabolizing enzymes

26. A 42-year-old man with a history of alcoholism is brought to the emergency room in a confused and delirious state. He has truncal ataxia and ophthalmoplegia. The most appropriate immediate course of action is to administer.

(a) Chlordiazepoxide

(b) Disulfiram

(c) Folic acid

(d) Lorazepam

(e) Thiamine 

27. Which one of the following statements about the bio-disposition of ethanol is accurate?

(a) Ethanol is absorbed at all levels of the gastrointestinal tract

(b) Acetic acid is the initial product of ethanol metabolism

(c) After an intravenous dose, plasma levels of ethanol are lower in women than in men

(d) The elimination of ethanol follows first-order kinetics

(e) Alcohol dehydrogenase exhibits genetic variability

28. Following is GABAA agonist

(a) Muscimol

(b) Baclofen

(c) Bicuculline

(d) None of the above

29. Chronic use of ethanol is reported to increase

(a) Alcohol dehydrogenase

(b) Aldehyde dehydrogenase

(c) Microsomal ethanol-oxidizing system activity

(d) Monoamine oxidase

(e) NADH dehydrogenase

30. The chronic abuse of alcohol predisposes to hepatic damage following overdose of acetaminophen because ethanol

(a) Blocks acetaminophen metabolism

(b) Causes thiamine deficiency

(c) Displaces acetaminophen from plasma proteins

(d) Induces liver drug-metabolizing enzymes

(e) Inhibits renal clearance of acetaminophen

31. The activity of this enzyme is specifically decreased in the Wernicke-Korsakoff syndrome

(a) Alcohol dehydrogenase

(b) Cytochrome P450

(c) L-Aromatic amino acid decarboxylase

 (d) NADH dehydrogenase

(e) Pyruvate dehydrogenase

32. Following is glycine antagonists

(a) Quisqualate

(b) Taurine

(c) Strychnine

(d) â-alanine

33. Which one of the following statements concerning the pharmacokinetics of

antiseizure drugs is accurate?

(a) At high doses, phenytoin elimination follows first-order kinetics

(b) Valporic acid may increase the activity of hepatic ALA synthase and the synthesis of porphyrins

(c) The administration of phenytoin to patients in methadone maintenance programs has led to symptoms of opioid overdose, including respiratory depression

(d) Although ethosuximide has a half-life of approximately 40 hours, the drug is usually taken twice a day

(e) Treatment with vigabatrin may reduce the effectiveness of oral contraceptives

34. With chronic use in seizure states, the adverse effects of this drug include coarsening of facial features, hirsutism, gingival hyperplasia, and osteomalacia.

(a) Carbamazepine

(b) Ethosuximide

(c) Gabapentin

(d) Phenytoin

(e) Valproic acid

35. Which one of the following statements about vigabatrin is accurate?

(a) Blocks neuronal reuptake of GABA

(b) Drug of choice in absence seizures

(c) Is established to be teratogenic in humans

(d) Life-threatening skin disorders may occur

(e) Visual field defects occur in up to one-third of patients

 

36. Withdrawal of antiseizure drugs can cause increased seizure frequency and severity. Withdrawal is least likely to be a problem with

(a) Clonazepam

(b) Diazepam

(c) Ethosuximide

(d) Phenobarbital

(e) Phenytoin

37. A young femal patient who suffers from bipolar affective disorder (BAD) has been managed with lithium. If she becomes pregnant, which one of the following

drugs is likely to be effective in bipolar affective disorder with minimal risk of teratogenicity?

(a) Carbamazepine

(b) Clonazepam

(c) Phenytoin

(d) Valproic acid

(e) None of the above

38. The most likely mechanism involved in the antiseizure activity of carbamazepine is

(a) Block of sodium ion channels

(b) Block of calcium ion channels

(c) Facilitation of GABA actions on chloride ion channels

(d) Glutamate receptor antagonism

(e) Inhibition of GABA transaminase

39. Which one of the following statements about phenytoin is accurate?

(a) Displaces sulfonamides from plasma proteins

(b) Drug of choice in myoclonic seizures

(c) Half-life is increased if used with pheno-barbital

(d) Isoniazid (INH) decreases steady state blood levels of phenytoin

(e) Toxicity may occur with only small increments in dose

40. Which one of the following statements concerning nitrous oxide is accurate?

(a) It continues to be a useful component of anesthesia protocols because of its lack of cardiovascular depression

(b) Megaloblastic anemia is a common adverse effect in patients exposed to nitrous oxide for periods longer than 2 hours

(c) It is the most potent of the inhaled anaesthetics

(d) There is a direct association between the use

of nitrous oxide and malignant hyperthermia

(e) More than 30% of nitrous oxide is eliminated via hepatic metabolism

41. Following is GABAB agonist

(a) Muscimol

(b) Baclofen

(c) Picrotoxin

(d) Bicuculline

42. Following is GABAA antagonist

(a) Muscimol

(b) Bicuculline

(c) Strychnine

 (d) Baclofen

43. The inhalation anesthetic with the fastest onset of action is

(a) Enflurane

(b) Isoflurane

(c) Nitric oxide

(d) Nitrogen dioxide

(e) Nitrous oxide

44. An intravenous bolus dose of thiopental usually leads to loss of onsciousness within 10–15 seconds. If no further drugs are administered, the patient will regain consciousness in just a few minutes. The reason for this, that thiopental is

(a) A good substrate for renal tubular secretion

(b) Exhaled rapidly

(c) Rapidly metabolized by hepatic enzymes

(d) Redistributed from brain to other body tissues

(e) Secreted in the bile

45. Respiratory depression following use of this agent may be reversed by adminis- tration of flumazenil

(a) Desflurane

(b) Fentanyl

(c) Ketamine

(d) Midazolam

(e) Propofol

46. Use of this agent is associated with a high incidence of disorientation, sensory and perceptual illusions, and vivid dreams during recovery from anesthesia

(a) Diazepam

(b) Fentanyl

(c) Ketamine

(d) Midazolam

(e) Thiopental

47. Postoperative vomiting is uncommon with this intravenous agent; patients are able to ambulate sooner than those who receive other anaesthetics.

(a) Enflurane

(b) Ketamine

(c) Morphine

(d) Propofol

(e) Remifentanil

48. The pKa of lidocaine is 7.9. In infected tissue at pH 6.9, the fraction in the ionized form will be

(a) 1%

(b) 10%

(c) 50%

(d) 90%

(e) 99%

49. Which of the following statements about nerve blockade with local anaesthetics is most correct?

(a) Block is faster in onset in infected tissues

(b) Block is faster in onset in unmyelinated fibers

(c) Block is slower in onset in hypocalcemia

(d) Block is faster in onset in hyperkalemia

(e) Block is slower in onset in the periphery of a nerve bundle than in the center of a bundle

50. Which of the following was the first com- pound to be identified Pharmacologically as a transmitter in the CNS ?

(a) Glycine

(b) Glutamate

(c) Acetulcholine

(d) Norepinephrine

 

ANSWER KEYS

1. d

2. a

3. a

4. e

5. a

6. c

7. e

8. b

9. b

10. d

11. a

12. b

13. a

14. e

15. d

16. a

17. d

18. d

19. a

20. c

21. b

22. c

23. c

24. e

25. a

26. e

27. a

28. a

29. c

30. d

31. e

32. c

33. d

34. d

35. e

36. c

37. b

38. a

39. e

40. a

41. b

42. b

43. e

44. d

45. d

46. c

47. d

48. d

49. d

50. c

 

EXPLANATIONS 

3.a Neurotransmitter is a substance present in neuron and is secreted by neurons to transmit signals to its postsynaptic targets.

8. b An example of neuromodulator is cAMP. It acts as a second messenger of synaptic transmission.

16. a Suramin is an antagonist of purinergic receptors, specifically P2x and P2y

20. c NMDA receptors are closely associated with the induction of synaptic plasticity. AMPA and kainite receptors are involved in mediation of fast depolarization.

28. a Muscimol is GABAA agonist. Baclofen is a GABAB agonist. Bicuculline is a GABAA antagonist.

32. c Strychnine is an antagonist of glycine receptors. Taurine and â-analine are agonists of glycine receptors. Quisqualate is an agonist of AMPA receptors.

41. b Baclofen is an agonist of GABAB receptor. Muscimol is an agonist of GABAA receptor. Picrotoxin and bicuculline are antagonists of GABAA receptors.

 

50. c In CNS, acetylcholine was the first neurotrans- mitter to be identified pharmacologically. In 1950s Eccles showed that excitation of Renshaw cells by motor axon collaterals was blocked by nicotinic antagonists.