Pentobarbital MCQs With Answer

Pentobarbital MCQs With Answer offers B.Pharm students a focused, exam-oriented revision tool on pentobarbital pharmacology. This SEO-friendly collection emphasizes core keywords such as pentobarbital, MCQs, mechanism of action, pharmacokinetics, adverse effects, drug interactions and overdose management. Questions explore GABA-A receptor modulation, hepatic metabolism, enzyme induction, clinical uses, contraindications (eg, porphyria, respiratory depression), dosing principles and emergency treatment. Designed for semester exams, practicals and competitive tests, these MCQs reinforce critical thinking, clinical application and retention of drug-specific details. Practice with clear answers to build confidence and improve performance in pharmacology assessments. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which class of drug does pentobarbital belong to?

• Short-acting barbiturate
• Benzodiazepine
• Opioid analgesic
• Antipsychotic

Correct Answer: Short-acting barbiturate

Q2. What is the primary mechanism of action of pentobarbital?

• Positive allosteric modulation of GABA-A receptors increasing chloride influx
• Competitive antagonism at NMDA receptors
• Inhibition of monoamine oxidase
• Blockade of voltage-gated sodium channels

Correct Answer: Positive allosteric modulation of GABA-A receptors increasing chloride influx

Q3. Pentobarbital primarily affects which neurotransmitter system?

• GABAergic system
• Cholinergic system
• Serotonergic system
• Dopaminergic system

Correct Answer: GABAergic system

Q4. Compared to phenobarbital, pentobarbital is:

• Shorter-acting and more lipophilic
• Longer-acting and less lipophilic
• Non-sedative
• Primarily an antihypertensive

Correct Answer: Shorter-acting and more lipophilic

Q5. The main route of elimination of pentobarbital is:

• Hepatic metabolism followed by renal excretion
• Unchanged renal excretion only
• Exhalation unchanged via lungs
• Biliary excretion exclusively

Correct Answer: Hepatic metabolism followed by renal excretion

Q6. Which enzyme system is induced by chronic pentobarbital therapy?

• CYP450 hepatic enzymes
• Monoamine oxidase A
• Acetylcholinesterase
• Tyrosine hydroxylase

Correct Answer: CYP450 hepatic enzymes

Q7. A serious acute adverse effect of pentobarbital overdose is:

• Respiratory depression leading to respiratory arrest
• Acute pancreatitis
• Hyperreflexia
• Severe hypertension

Correct Answer: Respiratory depression leading to respiratory arrest

Q8. Pentobarbital is contraindicated in patients with:

• Acute intermittent porphyria
• Hypothyroidism
• Mild allergic rhinitis
• Hypercholesterolemia

Correct Answer: Acute intermittent porphyria

Q9. Which of the following is a clinical use of pentobarbital?

• Short-term sedation and control of refractory seizures
• First-line chronic anxiety management
• Long-term insomnia therapy without tolerance
• Primary treatment of Parkinson’s disease

Correct Answer: Short-term sedation and control of refractory seizures

Q10. Which statement about pentobarbital pharmacokinetics is correct?

• It has rapid onset due to high lipid solubility
• It is not absorbed orally
• It is exclusively excreted unchanged in urine
• It does not cross the blood-brain barrier

Correct Answer: It has rapid onset due to high lipid solubility

Q11. In overdose, which treatment is NOT effective for pentobarbital poisoning?

• Flumazenil administration
• Supportive airway management
• Activated charcoal if early
• Consideration of hemodialysis in severe cases

Correct Answer: Flumazenil administration

Q12. Chronic use of pentobarbital may lead to which adaptation?

• Tolerance and physical dependence
• Permanent immunosuppression
• Increased insulin sensitivity
• Enhanced platelet aggregation

Correct Answer: Tolerance and physical dependence

Q13. Which drug interaction is expected with pentobarbital?

• Reduced plasma levels of warfarin due to CYP induction
• Inhibition of rifampicin metabolism
• Potentiation of epinephrine action
• Decreased effect of levodopa via receptor blockade

Correct Answer: Reduced plasma levels of warfarin due to CYP induction

Q14. Pentobarbital enhances the duration of GABA-A receptor-mediated chloride channel opening. This property is best described as:

• Positive allosteric modulation with direct agonist activity at high concentrations
• Competitive antagonism at the GABA binding site
• Selective GABA reuptake inhibition
• Non-competitive NMDA receptor blockade

Correct Answer: Positive allosteric modulation with direct agonist activity at high concentrations

Q15. Which clinical monitoring is most important when administering IV pentobarbital?

• Respiratory rate and oxygenation
• Serum amylase level
• Thyroid function tests
• Serial chest X-rays

Correct Answer: Respiratory rate and oxygenation

Q16. Pentobarbital use in pregnancy is associated with:

• Potential fetal harm and neonatal respiratory depression
• Protection against congenital malformations
• Enhanced fetal growth
• Prevention of gestational diabetes

Correct Answer: Potential fetal harm and neonatal respiratory depression

Q17. Which physical property contributes to pentobarbital’s rapid brain penetration?

• High lipid solubility
• Large molecular weight
• Strong ionization at physiological pH
• Extensive plasma protein binding preventing entry

Correct Answer: High lipid solubility

Q18. Which electrolyte abnormality may be monitored in severe pentobarbital overdose management?

• Hypoventilation-related respiratory acidosis with hypercapnia
• Severe hypernatremia without respiratory change
• Isolated hypocalcemia
• Marked hypokalemia unrelated to ventilation

Correct Answer: Hypoventilation-related respiratory acidosis with hypercapnia

Q19. Which symptom is characteristic of barbiturate withdrawal?

• Anxiety, tremors, and potential seizures
• Improved sleep and euphoria
• Bradycardia and increased appetite
• Hyporeflexia with weight gain

Correct Answer: Anxiety, tremors, and potential seizures

Q20. Pentobarbital’s effect on hepatic enzymes results in which clinical consequence?

• Decreased plasma levels of co-administered drugs metabolized by CYP450
• Immediate hepatotoxicity in all patients
• Inhibition of gluconeogenesis causing hypoglycemia
• Enhanced renal clearance of proteins

Correct Answer: Decreased plasma levels of co-administered drugs metabolized by CYP450

Q21. Which laboratory test may be useful to assess severe pentobarbital toxicity?

• Arterial blood gas and serum electrolytes
• Serum troponin only
• Thyroid-stimulating hormone exclusively
• Cerebrospinal fluid culture

Correct Answer: Arterial blood gas and serum electrolytes

Q22. Pentobarbital produces which effect on sleep architecture?

• Reduced REM sleep and altered sleep stages
• Increased REM sleep with vivid dreaming
• Complete normalization of sleep patterns
• No effect on sleep stages

Correct Answer: Reduced REM sleep and altered sleep stages

Q23. Which formulation of pentobarbital is commonly used in emergency settings?

• Intravenous sodium pentobarbital solution
• Transdermal patch
• Inhalation aerosol
• Topical cream

Correct Answer: Intravenous sodium pentobarbital solution

Q24. Pentobarbital is most likely to potentiate the depressant effects of which co-administered drug?

• Alcohol (ethanol)
• Metformin
• Levothyroxine
• Insulin

Correct Answer: Alcohol (ethanol)

Q25. For status epilepticus refractory to benzodiazepines, pentobarbital may be used to:

• Induce a barbiturate coma to suppress seizures
• Stimulate seizure activity for diagnosis
• Replace benzodiazepines for long-term therapy
• Prevent electrolyte imbalance

Correct Answer: Induce a barbiturate coma to suppress seizures

Q26. Which patient population requires special caution when using pentobarbital?

• Elderly patients due to increased sensitivity and fall risk
• Young athletes for performance enhancement
• Patients with hyperthyroidism for tremor control
• Individuals with stable mild asthma

Correct Answer: Elderly patients due to increased sensitivity and fall risk

Q27. Pentobarbital’s analgesic properties are:

• Minimal; it is primarily sedative-hypnotic rather than analgesic
• Equivalent to morphine
• Superior to NSAIDs for inflammatory pain
• Directly mediated by opioid receptors

Correct Answer: Minimal; it is primarily sedative-hypnotic rather than analgesic

Q28. Which of the following is a forensic/ethical use associated with pentobarbital?

• Use in physician-assisted euthanasia or lethal injection in some jurisdictions
• Common use as an over-the-counter sleep aid
• Preferred drug for pediatric ADHD
• Routine vaccination adjuvant

Correct Answer: Use in physician-assisted euthanasia or lethal injection in some jurisdictions

Q29. Which effect does pentobarbital have on cardiac function at therapeutic doses?

• Minimal direct cardiac stimulation but may cause hypotension due to vasodilation
• Marked positive inotropic effect
• Severe coronary vasospasm
• Chronic tachyarrhythmias in all patients

Correct Answer: Minimal direct cardiac stimulation but may cause hypotension due to vasodilation

Q30. When counseling patients, which warning is essential for those prescribed pentobarbital?

• Avoid alcohol and other CNS depressants due to additive respiratory depression
• It is safe to drive on the first dose
• It increases energy and alertness
• It cures anxiety permanently

Correct Answer: Avoid alcohol and other CNS depressants due to additive respiratory depression

Q31. Which pharmacokinetic property explains accumulation with repeated pentobarbital dosing?

• Hepatic metabolism with potential for enzyme saturation and variable half-life
• Immediate renal clearance without accumulation
• Complete first-pass elimination preventing systemic effect
• Exclusive biliary excretion with no hepatic metabolism

Correct Answer: Hepatic metabolism with potential for enzyme saturation and variable half-life

Q32. In patients with hepatic impairment, pentobarbital dosing should be:

• Reduced due to decreased metabolism and prolonged action
• Increased to overcome liver dysfunction
• Unchanged because elimination is renal only
• Stopped completely because it is renally cleared

Correct Answer: Reduced due to decreased metabolism and prolonged action

Q33. Which adverse effect is more likely with pentobarbital than with benzodiazepines?

• Severe respiratory depression and higher risk of fatal overdose
• Milder sedation with no dependence
• Selective REM sleep enhancement
• Lower potential for tolerance

Correct Answer: Severe respiratory depression and higher risk of fatal overdose

Q34. Pentobarbital’s classification by duration of action is:

• Short-acting barbiturate
• Ultra-long-acting barbiturate
• Intermediate-acting benzodiazepine
• Non-depolarizing muscle relaxant

Correct Answer: Short-acting barbiturate

Q35. Which statement about pentobarbital and enzyme induction is true?

• It can accelerate metabolism of oral anticoagulants, reducing their effect
• It universally inhibits all CYP enzymes
• It prevents metabolism of acetaminophen causing toxicity
• It only affects phase II conjugation reactions

Correct Answer: It can accelerate metabolism of oral anticoagulants, reducing their effect

Q36. Which sign would suggest severe central nervous system depression from pentobarbital?

• Coma with depressed reflexes and hypoventilation
• Hyperalertness and insomnia
• Fever with rigors
• Hypertension with tachycardia

Correct Answer: Coma with depressed reflexes and hypoventilation

Q37. Which dosing consideration is important for pediatric patients receiving pentobarbital?

• Careful weight-based dosing and monitoring of respiratory status
• Give adult doses regardless of weight
• No monitoring needed due to safety
• Use oral dosing only for severe seizures

Correct Answer: Careful weight-based dosing and monitoring of respiratory status

Q38. The onset of action after intravenous administration of pentobarbital is approximately:

• Rapid, within minutes
• Several hours
• Several days
• No measurable onset

Correct Answer: Rapid, within minutes

Q39. Which monitoring parameter helps detect early respiratory compromise from pentobarbital?

• Pulse oximetry and capnography
• Serum liver enzymes only
• Electrocardiogram exclusively
• Urine output without respiratory assessment

Correct Answer: Pulse oximetry and capnography

Q40. Which of the following is a differential point between pentobarbital and benzodiazepines?

• Barbiturates like pentobarbital can directly activate GABA-A at high doses; benzodiazepines cannot
• Benzodiazepines directly open chloride channels at high doses; barbiturates never do
• Pentobarbital is selective for serotonin receptors
• Benzodiazepines induce hepatic CYP enzymes more strongly than pentobarbital

Correct Answer: Barbiturates like pentobarbital can directly activate GABA-A at high doses; benzodiazepines cannot

Q41. Which adverse dermatologic reaction can occur with barbiturates including pentobarbital?

• Rash and hypersensitivity reactions, including Stevens-Johnson syndrome (rare)
• Immediate hair growth enhancement
• Permanent skin depigmentation in all users
• Universal improvement in acne

Correct Answer: Rash and hypersensitivity reactions, including Stevens-Johnson syndrome (rare)

Q42. In therapeutic drug monitoring, which factor complicates interpreting pentobarbital levels?

• Large interindividual variability in metabolism and protein binding
• Complete absence of plasma protein binding in all patients
• Levels remain constant regardless of dose
• Only urine levels are clinically useful

Correct Answer: Large interindividual variability in metabolism and protein binding

Q43. Which statement about pentobarbital and renal function is correct?

• Renal impairment may prolong elimination of metabolites and require dose adjustment
• Renal function has no impact on dosing
• Renal failure increases hepatic clearance dramatically
• Pentobarbital is cleared only by dialysis

Correct Answer: Renal impairment may prolong elimination of metabolites and require dose adjustment

Q44. Which of the following best describes tolerance to pentobarbital?

• Progressive decrease in sedative effect requiring higher doses
• Immediate hypersensitivity reaction after first dose
• Permanent immunity to CNS depressants
• Complete elimination of withdrawal symptoms

Correct Answer: Progressive decrease in sedative effect requiring higher doses

Q45. Which condition may be exacerbated by pentobarbital use due to respiratory depressant effects?

• Obstructive sleep apnea
• Iron-deficiency anemia
• Hyperthyroidism with tachycardia
• Dermatologic fungal infection

Correct Answer: Obstructive sleep apnea

Q46. Which monitoring is important during a pentobarbital-induced coma?

• Continuous EEG to assess burst-suppression and seizure control
• Weekly lipid profile only
• Monthly chest X-ray
• No monitoring is required once coma is induced

Correct Answer: Continuous EEG to assess burst-suppression and seizure control

Q47. Which laboratory method can be used to detect pentobarbital in biological samples?

• Gas chromatography-mass spectrometry (GC-MS)
• Complete blood count only
• Plain radiography
• Urine dipstick for glucose

Correct Answer: Gas chromatography-mass spectrometry (GC-MS)

Q48. Which coexisting condition increases the risk of adverse effects with pentobarbital?

• Chronic obstructive pulmonary disease (COPD)
• Mild seasonal allergies
• Controlled myopia
• Well-managed hyperlipidemia

Correct Answer: Chronic obstructive pulmonary disease (COPD)

Q49. Which statement is correct regarding pentobarbital and anesthesia?

• It can be used for induction of anesthesia and as a sedative in critical care
• It is the first-line neuromuscular blocking agent
• It is ineffective for any anesthetic purpose
• It is used to reverse opioid overdose

Correct Answer: It can be used for induction of anesthesia and as a sedative in critical care

Q50. Which precaution is essential when storing pentobarbital in a pharmacy setting?

• Keep in a controlled, secure location due to potential for abuse and regulation
• Store on open public shelves for easy access
• Mix with food items to disguise smell
• Store at high temperatures near radiators

Correct Answer: Keep in a controlled, secure location due to potential for abuse and regulation

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.

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