Mephobarbital MCQs With Answer

Introduction: Prepare for pharmacy exams with these Mephobarbital MCQs With Answer — a focused, exam-oriented resource for B.Pharm students studying barbiturate pharmacology. This concise introduction covers mephobarbital’s classification as an anticonvulsant barbiturate, mechanism of action on GABA-A receptors, pharmacokinetics including hepatic N‑demethylation to phenobarbital, clinical uses, adverse effects, drug interactions and toxicology. Each question reinforces key topics: mechanism, metabolism, therapeutic indications, contraindications, monitoring and overdose management. Ideal for revision, test practice and improving retention of essential concepts in pharmacology and therapeutics. Use these MCQs to sharpen clinical reasoning, recall important drug interactions and prepare for university and competitive examinations. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary therapeutic class of mephobarbital?

• Anticonvulsant and sedative-hypnotic
• Antidepressant
• Antipsychotic
• Cholinesterase inhibitor

Correct Answer: Anticonvulsant and sedative-hypnotic

Q2. Mephobarbital is best classified chemically as a derivative of which class?

• Benzodiazepine
• Barbituric acid (barbiturate)
• Hydantoin
• Succinimide

Correct Answer: Barbituric acid (barbiturate)

Q3. Which mechanism most accurately describes mephobarbital’s primary action at the synapse?

• Inhibition of NMDA receptors
• Blockade of sodium channels in axons
• Positive allosteric modulation of GABA-A receptors, increasing duration of Cl- channel opening
• Inhibition of monoamine oxidase

Correct Answer: Positive allosteric modulation of GABA-A receptors, increasing duration of Cl- channel opening

Q4. Mephobarbital is metabolized in the liver mainly by which process?

• N‑demethylation to phenobarbital
• Sulfation at the phenyl ring
• Hydrolysis to urea derivatives

Correct Answer: N‑demethylation to phenobarbital

Q5. The conversion of mephobarbital to phenobarbital makes it best described as which of the following?

• An inactive analogue

Correct Answer: A prodrug of phenobarbital

Q6. Which adverse effect is most characteristic of barbiturates like mephobarbital?

• Hypersalivation
• Central nervous system depression and respiratory depression
• Excessive sympathetic stimulation
• Marked hyperthermia

Correct Answer: Central nervous system depression and respiratory depression

Q7. Which patient condition is an important contraindication for mephobarbital use?

• Porphyria
• Controlled hypertension
• Mild seasonal allergies
• Well-controlled hypothyroidism

Correct Answer: Porphyria

Q8. Mephobarbital induces which of the following pharmacological processes that leads to many drug interactions?

Correct Answer: Induction of hepatic microsomal enzymes (CYP450)

Q9. Which drug effect is most likely when mephobarbital is coadministered with oral contraceptives?

• Increased contraceptive effectiveness
• No interaction
• Reduced contraceptive effectiveness due to enzyme induction
• Complete inhibition of contraceptive absorption

Correct Answer: Reduced contraceptive effectiveness due to enzyme induction

Q10. Therapeutic drug monitoring for mephobarbital is usually performed by measuring levels of which compound?

• Mephobarbital only
• Phenobarbital and mephobarbital (total active moieties)
• Serotonin
• Plasma acetylcholinesterase

Correct Answer: Phenobarbital and mephobarbital (total active moieties)

Q11. Which of the following best describes the clinical use of mephobarbital?

• Treatment of bacterial infections
• Long-term management of some seizure disorders and as a sedative
• First-line therapy for acute myocardial infarction
• As an anxiolytic for panic disorder exclusively

Correct Answer: Long-term management of some seizure disorders and as a sedative

Q12. The greatest risk during combined use of mephobarbital and benzodiazepines is:

• Gastrointestinal bleeding
• Severe additive CNS and respiratory depression
• Hypertensive crisis
• Hyperglycemia

Correct Answer: Severe additive CNS and respiratory depression

Q13. In overdose of mephobarbital, which immediate management step is most important?

• Administer naloxone
• Secure airway and support ventilation
• Give flumazenil
• Administer insulin

Correct Answer: Secure airway and support ventilation

Q14. Which laboratory parameter is most relevant to monitor for chronic mephobarbital therapy?

• ECG PR interval
• Liver function tests and complete blood count
• Serum potassium only
• Thyroid-stimulating hormone exclusively

Correct Answer: Liver function tests and complete blood count

Q15. Mephobarbital’s effect on GABA-A receptor is best described as:

• Partial agonist at the GABA binding site
• Competitive antagonist of GABA
• Allosteric modulator increasing chloride channel open time
• Blocker of chloride channels

Correct Answer: Allosteric modulator increasing chloride channel open time

Q16. Which structural position on barbituric acid derivatives commonly influences anticonvulsant potency?

• Substitution at N1 only
• Substitution at C5 (alkyl/aryl groups)
• Modification of the carbonyl oxygen
• Changes to the imide hydrogen

Correct Answer: Substitution at C5 (alkyl/aryl groups)

Q17. Which statement about mephobarbital’s protein binding is most accurate?

• It is completely unbound in plasma
• It has moderate plasma protein binding which can be displaced by other drugs
• It binds exclusively to red blood cells
• It irreversibly binds to albumin

Correct Answer: It has moderate plasma protein binding which can be displaced by other drugs

Q18. Mephobarbital can worsen which of the following respiratory conditions?

• Asthma via bronchospasm
• Chronic obstructive pulmonary disease (CNS and respiratory depression can worsen hypoventilation)
• Pulmonary embolism specifically
• Pneumothorax by increasing intrapleural pressure

Correct Answer: Chronic obstructive pulmonary disease (CNS and respiratory depression can worsen hypoventilation)

Q19. Which monitoring is important when mephobarbital is used during pregnancy?

• No monitoring required
• Fetal monitoring and counseling on teratogenic risk; weigh risks vs benefits
• Immediate discontinuation without consultation
• Only maternal blood glucose monitoring

Correct Answer: Fetal monitoring and counseling on teratogenic risk; weigh risks vs benefits

Q20. Mephobarbital is most likely to cause which endocrine effect with long-term therapy?

• Hyperthyroidism
• Inhibition of steroid metabolism leading to reduced efficacy of steroid hormones
• Increased cortisol production
• Stimulation of insulin release

Correct Answer: Inhibition of steroid metabolism leading to reduced efficacy of steroid hormones

Q21. Which of the following is the most appropriate method to increase renal elimination of barbiturates like phenobarbital (related to mephobarbital metabolism)?

• Urinary acidification
• Urinary alkalinization (forced alkaline diuresis)
• Hemodialysis is ineffective
• Administration of cholestyramine

Correct Answer: Urinary alkalinization (forced alkaline diuresis)

Q22. Compared to phenobarbital, mephobarbital’s analgesic properties are:

• Markedly superior
• Non-existent; both are primarily CNS depressants and anticonvulsants
• Significantly pro-inflammatory
• Primarily mediated by opioid receptors

Correct Answer: Non-existent; both are primarily CNS depressants and anticonvulsants

Q23. Which safety consideration is most important when dispensing mephobarbital to elderly patients?

• They have decreased risk of falls
• Increased sensitivity to CNS depression and risk of falls and cognitive impairment
• No dose adjustments are ever required
• It improves memory in elderly

Correct Answer: Increased sensitivity to CNS depression and risk of falls and cognitive impairment

Q24. Which laboratory test can be used to confirm a suspected severe barbiturate poisoning?

• Serum phenobarbital/mephobarbital concentration
• Serum troponin level
• Serum amylase only
• Thyroid hormone panel

Correct Answer: Serum phenobarbital/mephobarbital concentration

Q25. Which drug class is most likely to have reduced plasma concentrations when coadministered with mephobarbital?

• Antibiotics with no hepatic metabolism
• Drugs metabolized by CYP450 enzymes such as warfarin and oral contraceptives
• Intravenous saline
• Local anesthetics used topically

Correct Answer: Drugs metabolized by CYP450 enzymes such as warfarin and oral contraceptives

Q26. Mephobarbital use requires caution with which comorbid psychiatric condition?

• Major depressive disorder due to risk of worsening depression and suicidal ideation
• Seasonal affective disorder only
• Stable personality traits with no change
• Allergic rhinitis

Correct Answer: Major depressive disorder due to risk of worsening depression and suicidal ideation

Q27. Which of the following best describes tolerance and dependence with chronic mephobarbital therapy?

• Tolerance and physical dependence can develop, with withdrawal risks on abrupt cessation
• No tolerance occurs
• Dependence develops only after decades
• Drug produces immediate immunologic dependence

Correct Answer: Tolerance and physical dependence can develop, with withdrawal risks on abrupt cessation

Q28. In terms of seizure types, mephobarbital is most effective for which?

• All seizure types without exception
• Certain generalized tonic‑clonic seizures and some partial seizures
• Absence seizures as first-line monotherapy
• Psychogenic nonepileptic seizures only

Correct Answer: Certain generalized tonic‑clonic seizures and some partial seizures

Q29. Which formulation consideration is important for oral mephobarbital products?

• They must be refrigerated
• Stability in tablets and capsules at room temperature; ensure accurate dosing to avoid overdose
• They are always topical creams
• They should be stored in direct sunlight to activate the drug

Correct Answer: Stability in tablets and capsules at room temperature; ensure accurate dosing to avoid overdose

Q30. Which adverse hematologic reaction has been associated with prolonged use of some barbiturates?

• Agranulocytosis or pancytopenia
• Immediate polycythemia
• Platelet hyperfunction
• Increased hemoglobin only

Correct Answer: Agranulocytosis or pancytopenia

Q31. Which symptom is characteristic of barbiturate withdrawal?

• Euphoria without symptoms
• Anxiety, tremors, seizures and insomnia
• Increased appetite and weight gain
• Improved sleep quality

Correct Answer: Anxiety, tremors, seizures and insomnia

Q32. Which pharmacokinetic property explains why mephobarbital may have prolonged effects in chronic therapy?

• Rapid renal clearance only
• Accumulation due to long half-life of active metabolites like phenobarbital and tissue distribution
• Complete first-pass elimination so no systemic exposure
• Exclusive excretion via sweat

Correct Answer: Accumulation due to long half-life of active metabolites like phenobarbital and tissue distribution

Q33. Which safety counseling point is essential for a patient starting mephobarbital?

• Do not drive or operate heavy machinery until you know how it affects you
• Take extra vitamin C to negate side effects
• You can abruptly stop therapy anytime
• It will cure depression

Correct Answer: Do not drive or operate heavy machinery until you know how it affects you

Q34. Which of the following is a recognized effect of enzyme induction by barbiturates on laboratory assays?

• No effect on any assays
• False-low levels of drugs metabolized by induced enzymes (e.g., oral contraceptives, warfarin)
• Universal increase in all hormone levels
• Interference only with blood glucose measurements

Correct Answer: False-low levels of drugs metabolized by induced enzymes (e.g., oral contraceptives, warfarin)

Q35. A B.Pharm student should identify mephobarbital as which of the following in regulatory terms (generalized)?

• Over-the-counter vitamin supplement
• Controlled substance requiring prescription and monitoring
• Non-prescription herbal remedy
• Topical cosmetic product

Correct Answer: Controlled substance requiring prescription and monitoring

Q36. Which of the following interactions would be expected between mephobarbital and warfarin?

• Mephobarbital increases warfarin levels, increasing bleeding risk
• Mephobarbital-induced CYP enzymes may reduce warfarin effect, decreasing INR
• No interaction occurs
• Warfarin blocks mephobarbital absorption entirely

Correct Answer: Mephobarbital-induced CYP enzymes may reduce warfarin effect, decreasing INR

Q37. Which patient education point is important about alcohol consumption while taking mephobarbital?

• Alcohol has no effect on barbiturate action
• Alcohol can potentiate CNS depression; avoid drinking
• Alcohol reduces the half-life of mephobarbital
• Consume alcohol to prevent withdrawal

Correct Answer: Alcohol can potentiate CNS depression; avoid drinking

Q38. Which technique can be used in severe barbiturate poisoning to remove drug from circulation?

• Hemodialysis or charcoal hemoperfusion in severe cases
• Topical absorption therapy
• Activated charcoal is always contraindicated
• Intramuscular oil injections

Correct Answer: Hemodialysis or charcoal hemoperfusion in severe cases

Q39. Which of the following best explains why mephobarbital may have varied effects in pediatric patients?

• Children have identical pharmacokinetics to adults
• Differences in hepatic enzyme maturity and body composition alter metabolism and dosing
• Children are immune to CNS depressant effects
• Pediatrics require no monitoring

Correct Answer: Differences in hepatic enzyme maturity and body composition alter metabolism and dosing

Q40. Which one of the following laboratory results may suggest mephobarbital hepatotoxicity?

• Normal ALT and AST
• Elevation of ALT/AST and bilirubin
• Low serum creatinine only
• High hematocrit without liver enzyme change

Correct Answer: Elevation of ALT/AST and bilirubin

Q41. Which pharmacodynamic property differentiates barbiturates like mephobarbital from benzodiazepines?

• Barbiturates can directly activate GABA-A receptors at high doses, while benzodiazepines require GABA presence
• Benzodiazepines cause irreversible receptor blockade
• Barbiturates do not affect GABA receptors at all
• Both classes are identical in all effects

Correct Answer: Barbiturates can directly activate GABA-A receptors at high doses, while benzodiazepines require GABA presence

Q42. In formulation development, which excipient property is crucial for mephobarbital tablet stability?

• High acidity to catalyze degradation
• Neutral pH and low moisture to prevent hydrolysis
• High enzymatic content
• Light exposure to preserve potency

Correct Answer: Neutral pH and low moisture to prevent hydrolysis

Q43. Which of the following best describes mephobarbital’s potential to cause paradoxical reactions?

• No risk of paradoxical reactions
• May cause paradoxical excitement, especially in children or elderly
• Always causes euphoria without adverse effects
• Paradoxical reactions are only observed with antibiotics

Correct Answer: May cause paradoxical excitement, especially in children or elderly

Q44. Which pharmacokinetic term best describes the conversion of mephobarbital into an active metabolite?

• First-pass activation (bioactivation/prodrug conversion)
• Zero-order elimination only
• Complete renal excretion unchanged
• Transdermal absorption exclusively

Correct Answer: First-pass activation (bioactivation/prodrug conversion)

Q45. Which adverse effect would most likely prompt immediate discontinuation and urgent evaluation of mephobarbital therapy?

• Transient mild headache
• Signs of severe skin reaction (e.g., Stevens‑Johnson syndrome) or severe hepatotoxicity
• Mild dry mouth that resolves
• Temporary mild drowsiness on initiation

Correct Answer: Signs of severe skin reaction (e.g., Stevens‑Johnson syndrome) or severe hepatotoxicity

Q46. Which statement about mephobarbital and breastfeeding is most appropriate?

• It is always safe and requires no counseling
• It can be excreted in breast milk; benefits and risks should be weighed and alternatives considered
• It enhances milk production
• It neutralizes all pathogens in milk

Correct Answer: It can be excreted in breast milk; benefits and risks should be weighed and alternatives considered

Q47. Which adverse cardiovascular effect may occur with severe barbiturate toxicity?

• Severe hypotension and possible cardiovascular collapse
• Persistent hypertension with tachycardia only
• Isolated bradyarrhythmia without other signs
• No cardiovascular effects at any dose

Correct Answer: Severe hypotension and possible cardiovascular collapse

Q48. What is the primary rationale for gradual tapering of mephobarbital when discontinuing therapy?

• To prevent rebound hypertension
• To reduce risk of withdrawal symptoms including seizures and agitation
• To increase drug potency over time
• No rationale; abrupt cessation is preferable

Correct Answer: To reduce risk of withdrawal symptoms including seizures and agitation

Q49. Which laboratory assay technique is commonly used to quantify barbiturate concentrations in plasma for therapeutic monitoring?

• High-performance liquid chromatography (HPLC) or immunoassay
• Urine dipstick for glucose
• Complete blood count only
• Serum osmolarity exclusively

Correct Answer: High-performance liquid chromatography (HPLC) or immunoassay

Q50. For a B.Pharm student, which study focus will most improve clinical use of mephobarbital?

• Only learning brand names
• Understanding mechanism, metabolism, interactions, monitoring and toxicity management
• Memorizing pill color without context
• Studying unrelated vitamins

Correct Answer: Understanding mechanism, metabolism, interactions, monitoring and toxicity management

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