Ultra-short acting barbiturates – Methohexital sodium MCQs With Answer

Ultra-short acting barbiturates – Methohexital sodium MCQs With Answer

Methohexital sodium is an ultra-short acting barbiturate widely used for induction of anesthesia and electroconvulsive therapy (ECT). This concise introduction for B.Pharm students covers mechanism of action, pharmacokinetics, dosing, adverse effects, interactions, monitoring, and clinical uses. Key terms include ultra-short acting barbiturates, methohexital sodium, induction dose, redistribution, hepatic metabolism, respiratory depression, ECT anesthesia, and drug interactions. Understanding these concepts helps B.Pharm students counsel clinicians, prepare safe IV formulations, and anticipate complications. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary mechanism of action of methohexital?

• Blockade of NMDA receptors
• Inhibition of voltage-gated sodium channels
• Enhancement of GABA-A receptor-mediated chloride influx
• Activation of opioid receptors

Correct Answer: Enhancement of GABA-A receptor-mediated chloride influx

Q2. What is the typical onset of action for intravenous methohexital?

• 5–10 minutes
• 30–60 seconds
• 15–20 minutes
• 2–4 hours

Correct Answer: 30–60 seconds

Q3. What is the usual duration of hypnotic effect after a single IV bolus of methohexital?

• 24–48 hours
• 2–4 hours
• 5–10 minutes
• 30–60 minutes

Correct Answer: 5–10 minutes

Q4. Which clinical use is methohexital particularly favored for?

• Long-term sedation in ICU
• Induction of anesthesia and electroconvulsive therapy (ECT)
• Oral insomnia therapy
• Chronic neuropathic pain

Correct Answer: Induction of anesthesia and electroconvulsive therapy (ECT)

Q5. How is methohexital formulated for clinical use?

• As an oral syrup
• As an oil-based intramuscular injection
• As a water-soluble sodium salt for intravenous use
• As a transdermal patch

Correct Answer: As a water-soluble sodium salt for intravenous use

Q6. What is the primary route of metabolism for methohexital?

• Renal excretion of unchanged drug
• Metabolism by hepatic microsomal enzymes (oxidation)
• Metabolism by plasma esterases
• Excretion via bile unchanged

Correct Answer: Metabolism by hepatic microsomal enzymes (oxidation)

Q7. What is the approximate plasma protein binding of methohexital?

• Less than 10%
• Approximately 70% protein bound
• Nearly 100% bound
• Not protein bound at all

Correct Answer: Approximately 70% protein bound

Q8. In which condition is methohexital contraindicated or should be avoided?

• Acute intermittent porphyria
• Controlled hypertension
• Mild allergic rhinitis
• Uncomplicated myopia

Correct Answer: Acute intermittent porphyria

Q9. What is the most important acute adverse effect of methohexital to monitor for?

• Hyperreflexia
• Respiratory depression and apnea
• Hyperglycemia
• Excessive salivation only

Correct Answer: Respiratory depression and apnea

Q10. What is the first-line management for severe methohexital overdose?

• Administer flumazenil as specific antidote
• Rapid infusion of naloxone
• Supportive care with airway management and assisted ventilation
• Immediate gastric lavage for IV overdose

Correct Answer: Supportive care with airway management and assisted ventilation

Q11. Which of the following drug interactions is clinically significant with methohexital?

• Antagonism by beta-lactam antibiotics
• Additive CNS and respiratory depression with opioids and alcohol
• Reduced effect when coadministered with histamine H2 blockers
• No clinically relevant interactions

Correct Answer: Additive CNS and respiratory depression with opioids and alcohol

Q12. Why is methohexital often preferred for electroconvulsive therapy (ECT)?

• It is a strong anticonvulsant that shortens seizure
• It has minimal anticonvulsant activity, preserving seizure duration
• It causes prolonged muscle relaxation
• It increases intracranial pressure to improve ECT efficacy

Correct Answer: It has minimal anticonvulsant activity, preserving seizure duration

Q13. Which pharmacokinetic property explains the rapid onset of methohexital?

• Low lipid solubility
• High lipid solubility and rapid brain uptake
• Exclusively renal excretion
• Very high molecular weight preventing passage into CNS

Correct Answer: High lipid solubility and rapid brain uptake

Q14. Regarding use in pregnancy, which statement about methohexital is correct?

• It is completely safe and has no fetal effects
• Crosses the placenta and may cause neonatal respiratory depression; use with caution
• It cannot cross the placenta at all
• It is recommended for routine use in labor analgesia

Correct Answer: Crosses the placenta and may cause neonatal respiratory depression; use with caution

Q15. What is a commonly recommended induction dose of methohexital for an adult?

• 10–15 mg/kg IV bolus
• 1–1.5 mg/kg IV bolus
• 0.01 mg/kg IV bolus
• 50 mg orally

Correct Answer: 1–1.5 mg/kg IV bolus

Q16. Is there a specific pharmacologic antagonist for methohexital?

• Yes, flumazenil reverses methohexital
• Yes, naloxone reverses methohexital
• No specific antagonist; management is supportive
• Yes, physostigmine is the specific antagonist

Correct Answer: No specific antagonist; management is supportive

Q17. Compared with thiopental, how does recovery after methohexital compare?

• Recovery is much slower with methohexital
• Recovery is faster due to more rapid redistribution and metabolism
• Both have identical recovery profiles
• Methohexital causes permanent sedation

Correct Answer: Recovery is faster due to more rapid redistribution and metabolism

Q18. Methohexital belongs to which class of drugs?

• Benzodiazepines
• Opioids
• Ultra-short-acting barbiturates
• Inhalational anesthetics

Correct Answer: Ultra-short-acting barbiturates

Q19. What is the primary cardiovascular effect of methohexital at clinical doses?

• Marked increase in systemic vascular resistance
• Dose-dependent hypotension due to vasodilation
• Severe hypertension only
• No effect on blood pressure

Correct Answer: Dose-dependent hypotension due to vasodilation

Q20. How should methohexital be stored in the pharmacy or operating room?

• Frozen at −20°C
• Store at controlled room temperature, protected from light
• Exposed to light at all times to maintain potency
• Boiled before use to sterilize

Correct Answer: Store at controlled room temperature, protected from light

Q21. What is the usual pediatric induction dose of methohexital?

• 10 mg/kg orally
• 1–1.5 mg/kg IV (weight-based dosing)
• 0.01 mg/kg IM
• Same as adult without adjustment

Correct Answer: 1–1.5 mg/kg IV (weight-based dosing)

Q22. How does hepatic impairment affect methohexital pharmacokinetics?

• It shortens duration due to increased clearance
• It has no effect on methohexital levels
• It prolongs duration of action due to reduced metabolism
• It converts methohexital into an inactive metabolite immediately

Correct Answer: It prolongs duration of action due to reduced metabolism

Q23. How are methohexital metabolites primarily eliminated?

• Exhaled unchanged in breath
• Renal excretion of metabolites
• Primarily via sweat
• Integrated into hair shafts

Correct Answer: Renal excretion of metabolites

Q24. Which hypersensitivity concern applies to methohexital?

• It commonly causes serum sickness in all patients
• Anaphylaxis and hypersensitivity reactions are rare but possible
• It guarantees tolerance with no allergic reactions
• All patients develop skin necrosis

Correct Answer: Anaphylaxis and hypersensitivity reactions are rare but possible

Q25. Which statement about IV compatibility is appropriate for methohexital?

• Compatible with normal saline but should not be mixed with strongly alkaline solutions
• Can be mixed freely with any IV drug without concern
• Only compatible with 5% dextrose and nothing else
• Must be mixed with lactated Ringer’s for activation

Correct Answer: Compatible with normal saline but should not be mixed with strongly alkaline solutions

Q26. Which monitoring is essential during methohexital administration?

• Only blood glucose monitoring
• Continuous monitoring of oxygen saturation, ECG and capnography
• No monitoring is required for short procedures
• Only blood pressure every 2 hours

Correct Answer: Continuous monitoring of oxygen saturation, ECG and capnography

Q27. Which clinical signs characterize severe methohexital overdose?

• Coma, hypotension and hypoventilation
• Severe agitation and hyperthermia only
• Isolated rash without systemic signs
• Excessive urination and hypertension

Correct Answer: Coma, hypotension and hypoventilation

Q28. What is the role of activated charcoal in methohexital overdose?

• Highly effective for IV overdoses
• Of limited value for IV overdoses; focus is on supportive care
• The primary and only treatment option
• Causes rapid reversal of CNS depression

Correct Answer: Of limited value for IV overdoses; focus is on supportive care

Q29. How does chronic use of barbiturates like methohexital lead to tolerance?

• Decreased renal excretion
• Induction of hepatic enzymes and receptor-level adaptations
• Permanent increase in blood-brain barrier permeability
• Tolerance does not develop with barbiturates

Correct Answer: Induction of hepatic enzymes and receptor-level adaptations

Q30. What effect does methohexital have on hepatic drug metabolism?

• It inhibits all hepatic enzymes
• It induces hepatic microsomal enzymes, reducing levels of coadministered drugs
• It irreversibly destroys cytochrome P450
• It has no effect on other drugs

Correct Answer: It induces hepatic microsomal enzymes, reducing levels of coadministered drugs

Q31. Compared with propofol for induction, which is a practical difference favoring propofol?

• Propofol causes more postoperative nausea than methohexital
• Propofol provides smoother recovery and less postoperative nausea than methohexital
• Methohexital has a longer half-life than propofol making it better
• Propofol is an oral medication while methohexital is IV only

Correct Answer: Propofol provides smoother recovery and less postoperative nausea than methohexital

Q32. Is methohexital a trigger for malignant hyperthermia?

• Yes, it is a known trigger
• No, it does not trigger malignant hyperthermia and is considered safe
• Only when combined with benzodiazepines
• Only in pediatric patients

Correct Answer: No, it does not trigger malignant hyperthermia and is considered safe

Q33. What is the abuse potential of methohexital?

• No abuse potential; nonaddictive
• Has abuse and dependence potential as a sedative-hypnotic
• Causes immediate immunization so abuse is impossible
• Only addictive when taken orally

Correct Answer: Has abuse and dependence potential as a sedative-hypnotic

Q34. Is methohexital suitable for management of prolonged status epilepticus?

• Ideal for long-term control due to prolonged action
• Not preferred for long-term control due to short duration; useful for brief procedures
• Completely ineffective as an anticonvulsant
• Only useful when given orally

Correct Answer: Not preferred for long-term control due to short duration; useful for brief procedures

Q35. How should methohexital be administered to reduce risk of apnea during induction?

• Administer as a rapid IV push without monitoring
• Administer as a bolus over 15–30 seconds while monitoring respiration
• Always give intramuscularly to reduce apnea
• Administer subcutaneously for slow absorption

Correct Answer: Administer as a bolus over 15–30 seconds while monitoring respiration

Q36. What consideration applies to continuous infusion of methohexital?

• Continuous infusion never leads to accumulation
• Continuous infusion may lead to accumulation; monitor closely
• Continuous infusion is the preferred outpatient route
• Continuous infusion eliminates need for respiratory monitoring

Correct Answer: Continuous infusion may lead to accumulation; monitor closely

Q37. What effect does methohexital have on intracranial pressure (ICP) at clinical doses?

• Increases ICP markedly
• Decreases intracranial pressure due to cerebral vasoconstriction and reduced metabolism
• No effect on cerebral physiology
• Causes uncontrolled cerebral edema

Correct Answer: Decreases intracranial pressure due to cerebral vasoconstriction and reduced metabolism

Q38. What pediatric-specific risk is associated with methohexital?

• Increased risk of prolonged apnea in neonates and infants
• Guaranteed hyperactivity after administration
• Complete absence of sedative effect
• Enhanced growth in infants

Correct Answer: Increased risk of prolonged apnea in neonates and infants

Q39. What is the recommendation regarding breastfeeding after significant methohexital exposure?

• Safe to breastfeed immediately with no restrictions
• Enters breast milk; avoid breastfeeding for a period (e.g., 24 hours) after significant doses
• Causes permanent cessation of lactation
• Breastfeeding increases drug clearance instantly

Correct Answer: Enters breast milk; avoid breastfeeding for a period (e.g., 24 hours) after significant doses

Q40. Which of the following is a correct common trade name for methohexital sodium?

• Brevital sodium
• Versed
• Sublimaze
• Ketalar

Correct Answer: Brevital sodium

Q41. In overdose, what acid-base disturbance is most likely due to hypoventilation?

• Respiratory alkalosis
• Metabolic alkalosis
• Respiratory acidosis
• Metabolic acidosis only

Correct Answer: Respiratory acidosis

Q42. How do enzyme-inducing anticonvulsants affect methohexital levels?

• They decrease methohexital metabolism leading to toxicity
• They increase methohexital metabolism reducing its effect
• They have no impact on methohexital pharmacokinetics
• They convert methohexital to an inactive gas

Correct Answer: They increase methohexital metabolism reducing its effect

Q43. What EEG change can methohexital produce at high doses?

• Focal spike-and-wave only
• Produces generalized depression and can produce burst suppression at high doses
• Causes continuous seizure activity
• No change in EEG activity

Correct Answer: Produces generalized depression and can produce burst suppression at high doses

Q44. Is methohexital appropriate for short ambulatory procedures?

• Suitable for short ambulatory procedures as single bolus due to rapid recovery
• Never used in ambulatory settings
• Only used for multi-day sedation
• Used only as a topical agent for ambulatory care

Correct Answer: Suitable for short ambulatory procedures as single bolus due to rapid recovery

Q45. How does acute alcohol ingestion affect methohexital?

• Acute alcohol potentiates CNS depression
• Acute alcohol completely blocks methohexital action
• Acute alcohol reduces respiratory depression caused by methohexital
• No interaction between alcohol and methohexital

Correct Answer: Acute alcohol potentiates CNS depression

Q46. As a weak acid, how does pH influence methohexital ionization and CNS penetration?

• More unionized in acidic environments facilitating CNS penetration
• Always fully ionized regardless of pH
• More unionized in highly alkaline environments
• pH has no effect on ionization

Correct Answer: More unionized in acidic environments facilitating CNS penetration

Q47. How long should diluted methohexital solution typically be held in a syringe before use?

• Indefinitely; stability is unlimited
• Use promptly after dilution; avoid prolonged storage in syringe
• Store diluted syringes at room temperature for one month
• Freeze diluted syringes for future use

Correct Answer: Use promptly after dilution; avoid prolonged storage in syringe

Q48. What effect does methohexital have on cerebral blood flow?

• Increases cerebral blood flow markedly
• Reduces cerebral blood flow through cerebral vasoconstriction
• Has no effect on cerebral circulation
• Causes uncontrollable cerebral hemorrhage

Correct Answer: Reduces cerebral blood flow through cerebral vasoconstriction

Q49. How should dosing be adjusted in elderly patients receiving methohexital?

• No adjustment; elderly tolerate full adult doses
• Increase dose due to faster clearance
• Reduce dose due to decreased clearance and increased sensitivity
• Switch to oral route only

Correct Answer: Reduce dose due to decreased clearance and increased sensitivity

Q50. Which of the following summarizes methohexital’s clinical profile?

• Long-acting, poor choice for brief procedures, no respiratory effects
• Ultra-short-acting barbiturate used for induction and ECT with rapid onset, short duration, hepatic metabolism, and risk of respiratory depression
• Non-sedating analgesic used for chronic pain
• Topical anesthetic with no systemic absorption

Correct Answer: Ultra-short-acting barbiturate used for induction and ECT with rapid onset, short duration, hepatic metabolism, and risk of respiratory depression

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com