Barbiturate anticonvulsants – Methabarbital MCQs With Answer

Barbiturate anticonvulsants – Methabarbital MCQs With Answer

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Barbiturate anticonvulsants – Methabarbital MCQs With Answer

Barbiturate anticonvulsants, including methabarbital, remain important study topics for B. Pharm students due to their distinct mechanism of action, pharmacokinetics, adverse effects, and drug interactions. Methabarbital acts on GABA-A receptors, influencing chloride conductance and neuronal excitability. Understanding clinical uses in seizure control, dosing considerations, hepatic metabolism, enzyme induction, toxicity management, and formulation differences is crucial for safe therapeutic practice. These MCQs target mechanism, therapeutic indications, monitoring, contraindications, and management of overdose—designed to deepen comprehension beyond basics and sharpen exam readiness. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which is the primary mechanism of action of methabarbital as an anticonvulsant?

  • Inhibition of monoamine oxidase
  • Blockade of voltage-gated sodium channels
  • Positive allosteric modulation of GABA-A receptors
  • Antagonism of NMDA receptors

Correct Answer: Positive allosteric modulation of GABA-A receptors

Q2. At higher concentrations, barbiturates such as methabarbital can produce which additional effect on GABA-A receptors?

  • Increase glutamate release
  • Directly open chloride channels independent of GABA
  • Block GABA binding
  • Activate glycine receptors instead

Correct Answer: Directly open chloride channels independent of GABA

Q3. Methabarbital belongs to which chemical class of anticonvulsants?

  • Benzodiazepines
  • Barbiturates
  • Hydantoin derivatives
  • Sulfonamides

Correct Answer: Barbiturates

Q4. Which pharmacokinetic property largely determines the onset and duration of action of barbiturate drugs?

  • Renal clearance
  • Lipid solubility
  • Plasma protein binding only
  • pKa value exclusively

Correct Answer: Lipid solubility

Q5. Which of the following clinical uses is most appropriate for methabarbital?

  • Treatment of chronic bacterial infections
  • Long-term anticoagulation
  • Adjunctive control of certain seizure disorders
  • First-line therapy for hypertension

Correct Answer: Adjunctive control of certain seizure disorders

Q6. Barbiturates commonly induce which hepatic enzyme system affecting drug interactions?

  • CYP3A4 and other cytochrome P450 enzymes
  • MAO enzymes
  • Glutathione synthetase only
  • Acetylcholinesterase

Correct Answer: CYP3A4 and other cytochrome P450 enzymes

Q7. A major adverse effect of methabarbital therapy is:

  • Severe hyperglycemia
  • Respiratory depression
  • Excessive salivation only
  • Increased myocardial contractility

Correct Answer: Respiratory depression

Q8. Which patient history is a relative contraindication for methabarbital use?

  • Seasonal allergic rhinitis
  • History of porphyria
  • Mild acne
  • Orthodontic treatment

Correct Answer: History of porphyria

Q9. In overdose of phenobarbital-like barbiturates, which elimination-enhancing therapy is commonly used?

  • Urinary acidification
  • Urinary alkalinization
  • Proton pump inhibition
  • Serum albumin infusion

Correct Answer: Urinary alkalinization

Q10. Chronic use of methabarbital can lead to which of the following neuropsychiatric effects?

  • Heightened alertness and insomnia
  • Physical dependence and tolerance
  • Permanent improvement in memory
  • Selective increase in IQ

Correct Answer: Physical dependence and tolerance

Q11. Which monitoring parameter is most relevant when a patient is on long-term barbiturate therapy?

  • Serum sodium every 6 hours
  • Liver function tests and clinical signs of sedation
  • Daily platelet counts
  • Capillary glucose hourly

Correct Answer: Liver function tests and clinical signs of sedation

Q12. Methabarbital’s interaction with warfarin is most likely to cause:

  • Decreased warfarin metabolism leading to bleeding
  • Increased warfarin metabolism reducing anticoagulant effect
  • No interaction at all
  • Immediate reversal of warfarin effects

Correct Answer: Increased warfarin metabolism reducing anticoagulant effect

Q13. Which seizure type is barbiturate therapy particularly effective against?

  • Absence seizures exclusively
  • Febrile seizures in neonates and generalized tonic-clonic seizures
  • All psychogenic non-epileptic events
  • Myoclonic seizures only

Correct Answer: Febrile seizures in neonates and generalized tonic-clonic seizures

Q14. What is the principal reason barbiturates were largely replaced by benzodiazepines and newer AEDs?

  • Higher manufacturing cost
  • Narrower spectrum of action
  • Greater risk of dependence, overdose, and enzyme induction
  • No oral formulations available

Correct Answer: Greater risk of dependence, overdose, and enzyme induction

Q15. Which statement about methabarbital metabolism is correct?

  • It is primarily excreted unchanged in urine
  • It undergoes hepatic metabolism and can be affected by enzyme inducers/inhibitors
  • It is metabolized solely by renal glucuronidation
  • It is not metabolized and accumulates in adipose tissue only

Correct Answer: It undergoes hepatic metabolism and can be affected by enzyme inducers/inhibitors

Q16. In a patient taking methabarbital, co-administration of which drug class may lead to additive CNS depression?

  • Beta-blockers
  • Opioids and alcohol
  • Topical antibiotics
  • Proton pump inhibitors

Correct Answer: Opioids and alcohol

Q17. Which clinical sign is most indicative of severe barbiturate toxicity?

  • Mild headache without other symptoms
  • Coma with hypoventilation and hypotension
  • Localized rash only
  • Transient tinnitus alone

Correct Answer: Coma with hypoventilation and hypotension

Q18. Which lab test can help assess respiratory compromise in barbiturate overdose?

  • Serum troponin
  • Arterial blood gas analysis
  • Fasting lipid profile
  • Serum amylase

Correct Answer: Arterial blood gas analysis

Q19. Pharmacologically, barbiturates differ from benzodiazepines because they:

  • Only act on serotonin receptors
  • Can directly open GABA-A chloride channels at high concentrations
  • Are selective agonists at GABA-B receptors
  • Increase glutamate release

Correct Answer: Can directly open GABA-A chloride channels at high concentrations

Q20. Which formulation consideration is important for methabarbital oral tablets?

  • Avoid enteric coating because it accelerates absorption
  • Ensure stability under normal humidity and store in tight container
  • Tablets must be refrigerated at all times
  • They should be administered only as an intravenous solution

Correct Answer: Ensure stability under normal humidity and store in tight container

Q21. Which patient population requires extra caution or avoidance when prescribing methabarbital?

  • Patients with controlled hypothyroidism
  • Pregnant women and lactating mothers due to teratogenicity and neonatal depression risk
  • Patients with seasonal allergies
  • Individuals on topical antifungal creams

Correct Answer: Pregnant women and lactating mothers due to teratogenicity and neonatal depression risk

Q22. Which of the following describes tolerance development to barbiturates?

  • Tolerance does not occur with chronic use
  • Tolerance rapidly develops to sedative effects but less so to respiratory depression
  • Tolerance occurs only for anticonvulsant effects
  • Tolerance results in immediate drug sensitivity

Correct Answer: Tolerance rapidly develops to sedative effects but less so to respiratory depression

Q23. Which drug interaction elevates plasma levels of methabarbital?

  • Co-administration with potent CYP inhibitors
  • Concurrent use with CYP inducers
  • Taking with antacids only
  • Combination with vitamin C

Correct Answer: Co-administration with potent CYP inhibitors

Q24. Withdrawal from chronic barbiturate use is best characterized by:

  • Asymptomatic discontinuation
  • Potentially life-threatening symptoms including anxiety, tremors, and seizures
  • Only mild gastrointestinal upset
  • Immediate improvement in cognition

Correct Answer: Potentially life-threatening symptoms including anxiety, tremors, and seizures

Q25. Which monitoring is useful to detect chronic hepatic effects of barbiturate therapy?

  • Weekly ECG
  • Periodic liver function tests (AST, ALT, bilirubin)
  • Daily urine culture
  • Monthly chest X-ray

Correct Answer: Periodic liver function tests (AST, ALT, bilirubin)

Q26. Which property increases the risk of accumulation with long-term barbiturate therapy?

  • Low protein binding
  • Long elimination half-life and high lipid solubility
  • Rapid renal excretion without metabolism
  • Exclusively topical administration

Correct Answer: Long elimination half-life and high lipid solubility

Q27. Which of the following best describes methabarbital’s effect on sleep architecture?

  • Increases REM sleep markedly
  • Suppresses REM sleep and deep slow-wave sleep
  • Has no effect on sleep stages
  • Only enhances circadian rhythm amplitude

Correct Answer: Suppresses REM sleep and deep slow-wave sleep

Q28. Which statement about protein binding of barbiturates is correct?

  • Barbiturates are not protein bound at all
  • Many barbiturates are moderately to highly protein bound, affecting free drug levels
  • Protein binding only affects topical antivirals
  • Protein binding prevents any drug interactions

Correct Answer: Many barbiturates are moderately to highly protein bound, affecting free drug levels

Q29. Which of the following is an appropriate emergency measure in acute barbiturate overdose?

  • Immediate administration of flumazenil
  • Supportive care: airway management, ventilation, and circulatory support
  • Give benzodiazepines to reverse sedation
  • Induce emesis in an unconscious patient

Correct Answer: Supportive care: airway management, ventilation, and circulatory support

Q30. Which anticonvulsant property is least associated with barbiturates?

  • Enhancement of inhibitory GABAergic transmission
  • Direct blockade of sodium channels as primary mechanism
  • Production of CNS depression
  • Ability to induce hepatic enzymes

Correct Answer: Direct blockade of sodium channels as primary mechanism

Q31. Which factor increases free (active) fraction of a highly protein-bound barbiturate?

  • Concurrent hypoalbuminemia
  • Elevated albumin levels
  • Administration with oral iron supplements
  • Reduced renal clearance only

Correct Answer: Concurrent hypoalbuminemia

Q32. Which statement about methabarbital dosing considerations is correct?

  • Start at the maximum dose for all patients
  • Individualize dose based on response, age, hepatic function, and interactions
  • There is no need for dose adjustment in hepatic impairment
  • Dosing is identical for neonates and adults

Correct Answer: Individualize dose based on response, age, hepatic function, and interactions

Q33. Which adverse dermatologic reaction can occur with barbiturate therapy?

  • Stevens-Johnson syndrome (rare but possible)
  • Only non-specific dryness
  • Painless nail growth
  • Exclusive photosensitivity without rash

Correct Answer: Stevens-Johnson syndrome (rare but possible)

Q34. When counseling patients on methabarbital, which instruction is essential?

  • It is safe to drive until you know how it affects you
  • Avoid alcohol and other CNS depressants while taking the drug
  • Stop abruptly if you miss a dose
  • Double the next dose if one is missed

Correct Answer: Avoid alcohol and other CNS depressants while taking the drug

Q35. Which method can enhance elimination of phenobarbital and some barbiturates in severe poisoning?

  • Hemodialysis
  • Activated charcoal only after 48 hours
  • High-dose corticosteroids
  • Topical emollients

Correct Answer: Hemodialysis

Q36. Which receptor subunit interaction underlies barbiturate action on GABA-A?

  • Direct binding to opioid receptors
  • Allosteric binding on GABA-A receptor complex enhancing GABA effect
  • Competitive antagonism at nicotinic receptors
  • Blockade of dopamine D2 receptors

Correct Answer: Allosteric binding on GABA-A receptor complex enhancing GABA effect

Q37. Which is a characteristic pharmacodynamic effect of methabarbital at therapeutic doses?

  • Stimulation of the reticular activating system
  • Central nervous system depression and anticonvulsant activity
  • Potent peripheral vasoconstriction
  • Selective cholinergic activation

Correct Answer: Central nervous system depression and anticonvulsant activity

Q38. In formulation development, methabarbital is best categorized by which Biopharmaceutics classification attribute?

  • Highly water-soluble, non-permeable
  • Variable lipid solubility affecting oral bioavailability and onset
  • Completely non-absorbable
  • Only used as an inhalation anesthetic

Correct Answer: Variable lipid solubility affecting oral bioavailability and onset

Q39. Which laboratory result might reflect enzyme induction from chronic barbiturate therapy?

  • Decreased clearance of co-administered drugs metabolized by CYP enzymes
  • Unchanged levels of all concomitant medications
  • Increased plasma levels of drugs metabolized by induced enzymes
  • Decreased plasma levels of drugs metabolized by induced enzymes

Correct Answer: Decreased plasma levels of drugs metabolized by induced enzymes

Q40. Which statement best summarizes the role of methabarbital in modern anticonvulsant therapy?

  • First-line for all epilepsy types due to safety
  • Used less frequently today but important in specific indications and as historical basis for understanding barbiturates
  • No longer of any clinical or educational relevance
  • Preferred for treatment of bacterial meningitis

Correct Answer: Used less frequently today but important in specific indications and as historical basis for understanding barbiturates

Q41. Which pharmacological property explains rapid CNS penetration of some barbiturates?

  • High molecular weight only
  • High lipid solubility facilitating blood-brain barrier crossing
  • Exclusive renal transport mechanisms
  • Active transport via P-glycoprotein into the brain

Correct Answer: High lipid solubility facilitating blood-brain barrier crossing

Q42. In treating neonatal seizures, which barbiturate is most commonly referenced historically?

  • Phenobarbital
  • Pentobarbital exclusively
  • Methotrexate
  • Diazepam only

Correct Answer: Phenobarbital

Q43. Which effect on cardiovascular system can occur with barbiturate overdose?

  • Severe hypertension only
  • Hypotension due to vasodilation and myocardial depression
  • Marked bradycardia with hypertension
  • Immediate increase in cardiac output

Correct Answer: Hypotension due to vasodilation and myocardial depression

Q44. Which precaution is important when switching a patient from methabarbital to another antiepileptic?

  • Immediate abrupt discontinuation is safe
  • Gradual cross-tapering to avoid withdrawal seizures
  • No need to consider interactions
  • Cease all other medications during the switch

Correct Answer: Gradual cross-tapering to avoid withdrawal seizures

Q45. Which symptom is typical during early barbiturate withdrawal?

  • Excessive calmness and sedation
  • Anxiety, tremor, insomnia, and autonomic hyperactivity
  • Improved seizure control without medication
  • Acute renal colic only

Correct Answer: Anxiety, tremor, insomnia, and autonomic hyperactivity

Q46. Which statement about pediatric use of barbiturates is correct?

  • Children always require higher mg/kg doses than adults without exception
  • Careful dosing and monitoring are required due to variable metabolism and sensitivity
  • There are no age-related pharmacokinetic differences
  • Barbiturates are contraindicated in all children

Correct Answer: Careful dosing and monitoring are required due to variable metabolism and sensitivity

Q47. Which laboratory or clinical measure is least useful for routine monitoring of methabarbital therapy?

  • Assessment of sedation and cognitive function
  • Periodic liver function tests
  • Daily serum drug level measurement for every patient
  • Evaluation for signs of dependence and interactions

Correct Answer: Daily serum drug level measurement for every patient

Q48. Which class of drugs can have reduced efficacy when given with chronic barbiturate therapy due to enzyme induction?

  • Oral contraceptives
  • Topical emollients
  • Inhaled bronchodilators only
  • Topical antifungals only

Correct Answer: Oral contraceptives

Q49. Which counseling point addresses drug storage and safety for methabarbital?

  • Store within reach of children for easy dosing
  • Keep in original container, tightly closed, away from children and heat
  • Mix with other household medicines for convenience
  • Dispose of any unused drug down the sink

Correct Answer: Keep in original container, tightly closed, away from children and heat

Q50. For pharmacists, which responsibility is critical when dispensing methabarbital?

  • Ignore patient medication history
  • Verify drug interactions, counsel on CNS depression risks, and ensure safe storage
  • Recommend doubling doses if seizures persist without consulting prescriber
  • Encourage simultaneous alcohol consumption to improve sleep

Correct Answer: Verify drug interactions, counsel on CNS depression risks, and ensure safe storage

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