Skeletal muscle relaxants (peripheral) MCQs With Answer

Skeletal muscle relaxants (peripheral) MCQs With Answer

Peripheral skeletal muscle relaxants include neuromuscular blocking agents and direct-acting peripheral spasmolytics used in anesthesia and specific clinical settings. This concise, keyword-rich introduction covers classification (depolarizing vs non-depolarizing), representative drugs (succinylcholine, rocuronium, vecuronium, atracurium, cisatracurium, dantrolene, botulinum toxin), mechanisms at the nicotinic receptor and ryanodine receptor, pharmacokinetics (Hofmann elimination, hepatic/renal metabolism), monitoring (TOF), reversal strategies (neostigmine, sugammadex), and key adverse effects (malignant hyperthermia, hyperkalemia, histamine release). Tailored for B.Pharm students, these MCQs deepen understanding of clinical use, interactions, and safe medication management. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which receptor subtype is primarily blocked by peripheral neuromuscular blocking agents at the neuromuscular junction?

• Muscarinic M2 receptor
• Nicotinic N1 (muscle-type) receptor
• Nicotinic N2 (autonomic ganglia) receptor
• GABA-A receptor

Correct Answer: Nicotinic N1 (muscle-type) receptor

Q2. Which drug is a depolarizing neuromuscular blocker commonly used for rapid sequence intubation?

• Rocuronium
• Succinylcholine
• Vecuronium
• Atracurium

Correct Answer: Succinylcholine

Q3. Which mechanism best describes how succinylcholine causes muscle relaxation?

• Competitive antagonism at nicotinic receptors
• Prolonged depolarization of the motor end plate
• Inhibition of acetylcholine synthesis
• Block of voltage-gated sodium channels in muscle

Correct Answer: Prolonged depolarization of the motor end plate

Q4. Which non-depolarizing neuromuscular blocker is primarily eliminated by Hofmann degradation?

• Pancuronium
• Atracurium
• Pancuronium
• Rocuronium

Correct Answer: Atracurium

Q5. Which adverse effect is characteristically associated with succinylcholine in burn or severe trauma patients?

• Severe hypokalemia
• Hyperkalemia leading to cardiac arrhythmias
• Prolonged sedation due to renal retention
• Significant bronchospasm in all patients

Correct Answer: Hyperkalemia leading to cardiac arrhythmias

Q6. Which drug specifically binds and inactivates steroidal non-depolarizing neuromuscular blockers like rocuronium?

• Sugammadex
• Neostigmine
• Edrophonium
• Atropine

Correct Answer: Sugammadex

Q7. What is the primary clinical use of dantrolene among peripheral skeletal muscle relaxants?

• Treatment of organophosphate poisoning
• Management of malignant hyperthermia and spasticity
• Reversal of non-depolarizing neuromuscular blockade
• Antagonism of benzodiazepine overdose

Correct Answer: Management of malignant hyperthermia and spasticity

Q8. Which statement correctly contrasts potency and onset of neuromuscular blockers?

• Higher potency correlates with faster onset in all agents
• More potent agents often have slower onset due to lower dosing per volume
• Potency and onset are unrelated; onset is solely determined by renal function
• Onset is determined only by route of administration

Correct Answer: More potent agents often have slower onset due to lower dosing per volume

Q9. Which monitoring technique is standard to assess depth of neuromuscular blockade intraoperatively?

• Continuous pulse oximetry
• Train-of-four (TOF) peripheral nerve stimulation
• Capnography alone
• Serum acetylcholine levels

Correct Answer: Train-of-four (TOF) peripheral nerve stimulation

Q10. Which medication is used to reverse non-depolarizing neuromuscular blockade by inhibiting acetylcholinesterase?

• Sugammadex
• Neostigmine
• Succinylcholine
• Dantrolene

Correct Answer: Neostigmine

Q11. Which non-depolarizing agent is known for cardiovascular stimulation and tachycardia due to vagolytic effects?

• Pancuronium
• Mivacurium
• Cisatracurium
• Baclofen

Correct Answer: Pancuronium

Q12. Why are amino glycoside antibiotics clinically relevant when given with neuromuscular blockers?

• They antagonize neuromuscular blockers, reducing effect
• They potentiate neuromuscular blockade by inhibiting presynaptic ACh release
• They increase hepatic metabolism of neuromuscular blockers
• They convert depolarizing block to non-depolarizing block

Correct Answer: They potentiate neuromuscular blockade by inhibiting presynaptic ACh release

Q13. Which feature distinguishes phase II block from phase I block with succinylcholine?

• Phase II shows sustained depolarization without fade on TOF
• Phase II resembles non-depolarizing block with fade on TOF
• Phase II is characterized by fasciculations only
• Phase II cannot be reversed by acetylcholinesterase inhibitors

Correct Answer: Phase II resembles non-depolarizing block with fade on TOF

Q14. Which metabolic pathway accounts for the spontaneous breakdown of atracurium in plasma?

• CYP3A4 oxidation
• Hofmann elimination and ester hydrolysis
• Renal excretion unchanged only
• Glucuronidation in the liver

Correct Answer: Hofmann elimination and ester hydrolysis

Q15. Botulinum toxin exerts its peripheral muscle relaxant effect by which mechanism?

• Blocking nicotinic receptors at the motor end plate
• Cleaving SNARE proteins and preventing acetylcholine release
• Inhibiting acetylcholinesterase in the synaptic cleft
• Depolarizing the motor end plate similar to succinylcholine

Correct Answer: Cleaving SNARE proteins and preventing acetylcholine release

Q16. Which volatile anesthetic interaction increases the risk of malignant hyperthermia when combined with succinylcholine?

• Isoflurane
• Local anesthetics like lidocaine
• Non-depolarizing blockers like vecuronium
• Barbiturates

Correct Answer: Isoflurane

Q17. Which lab or clinical sign is most indicative of malignant hyperthermia after anesthesia?

• Progressive hyperkalemia without fever
• Rapid rise in end-tidal CO2 and muscle rigidity
• Decreased creatine kinase and bradycardia
• Hypothermia with decreased oxygen consumption

Correct Answer: Rapid rise in end-tidal CO2 and muscle rigidity

Q18. Which non-depolarizing neuromuscular blocker has the fastest onset suitable as an alternative to succinylcholine?

• Pancuronium
• Rocuronium
• Atracurium
• Cisatracurium

Correct Answer: Rocuronium

Q19. Which patient condition increases sensitivity to non-depolarizing neuromuscular blockers, requiring dose reduction?

• Chronic anticonvulsant therapy
• Myasthenia gravis
• Acute hyperkalemia
• Metabolic alkalosis

Correct Answer: Myasthenia gravis

Q20. Which effect is commonly seen with histamine-releasing neuromuscular blockers like tubocurarine?

• Hypertension and tachycardia without bronchospasm
• Hypotension and bronchospasm due to histamine release
• Hyperthermia and rigidity
• Excessive salivation and miosis

Correct Answer: Hypotension and bronchospasm due to histamine release

Q21. Which pharmacokinetic factor most strongly influences recovery time after non-depolarizing blockade?

• Plasma protein binding only
• Drug redistribution, metabolism, and excretion
• Rate of succinylcholine hydrolysis
• Concurrent opioid dosing only

Correct Answer: Drug redistribution, metabolism, and excretion

Q22. Which condition is a contraindication to use of succinylcholine due to risk of severe hyperkalemia?

• Short-term immobilization less than 24 hours
• Burns >24 hours post-injury and severe muscle trauma
• Controlled asthma without airway compromise
• Pregnancy in the first trimester

Correct Answer: Burns >24 hours post-injury and severe muscle trauma

Q23. Which monitoring finding indicates adequate recovery from neuromuscular blockade for safe extubation?

• TOF ratio ≥ 0.9
• TOF count of 1 with fade
• Complete lack of twitch response
• Patient spontaneously opens eyes only

Correct Answer: TOF ratio ≥ 0.9

Q24. Which drug’s duration is most likely prolonged in patients with hepatic failure?

• Atracurium
• Rocuronium
• Cisatracurium
• Succinycholine

Correct Answer: Rocuronium

Q25. Which adverse effect is specifically prevented by giving atropine or glycopyrrolate with neostigmine during reversal?

• Bradycardia and muscarinic overstimulation
• Neostigmine-induced hyperthermia
• Increased neuromuscular blockade potency
• Histamine-mediated bronchospasm

Correct Answer: Bradycardia and muscarinic overstimulation

Q26. Which statement about cisatracurium is true compared to atracurium?

• Cisatracurium is more dependent on renal clearance
• Cisatracurium produces less laudanosine and histamine than atracurium
• Cisatracurium has a significantly longer onset time than atracurium
• Cisatracurium cannot be used in renal failure due to accumulation

Correct Answer: Cisatracurium produces less laudanosine and histamine than atracurium

Q27. Which mechanism explains potentiation of neuromuscular blockade by hypothermia?

• Increased Hofmann elimination
• Decreased metabolism and reduced enzyme activity prolonging drug action
• Enhanced hepatic clearance
• Cold-induced antagonism of neuromuscular blockers

Correct Answer: Decreased metabolism and reduced enzyme activity prolonging drug action

Q28. In organophosphate poisoning, which agent is used as a peripheral antispasmodic rather than a neuromuscular blocker?

• Neostigmine
• Atropine
• Sugammadex
• Rocuronium

Correct Answer: Atropine

Q29. Which laboratory parameter commonly rises due to extensive muscle damage from prolonged sustained contraction in malignant hyperthermia?

• Serum sodium
• Serum creatine kinase (CK)
• Serum albumin
• Serum vitamin D

Correct Answer: Serum creatine kinase (CK)

Q30. Which clinical use best matches botulinum toxin as a peripheral skeletal muscle relaxant?

• Treatment of generalized myasthenia gravis
• Local relief of focal dystonias, spasticity, and cosmetic reduction of wrinkles
• Rapid sequence induction in emergency airway management
• Reversal of non-depolarizing neuromuscular blockade

Correct Answer: Local relief of focal dystonias, spasticity, and cosmetic reduction of wrinkles

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