Centrally acting muscle relaxants MCQs With Answer provide B. Pharm students a focused review of pharmacology, mechanisms, clinical uses, adverse effects and pharmacokinetics of agents such as baclofen, tizanidine, diazepam, cyclobenzaprine and carisoprodol. This topic emphasizes GABA‑B and GABA‑A modulation, alpha‑2 adrenergic agonism, central sedation, drug interactions (CYP, CNS depressants), renal/hepatic handling, withdrawal syndromes and safe prescribing in special populations. Clinical scenarios, toxicology and distinction from peripheral agents (dantrolene, botulinum) are covered to enhance therapeutic reasoning. The MCQs below are designed to deepen understanding and prepare you for exams and practical pharmacy decisions. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which of the following best describes the primary mechanism of action of baclofen?
- GABA-A receptor positive allosteric modulation
- GABA-B receptor agonism reducing presynaptic neurotransmitter release
- Alpha-2 adrenergic antagonism in the spinal cord
- Direct inhibition of sarcoplasmic reticulum calcium release
Correct Answer: GABA-B receptor agonism reducing presynaptic neurotransmitter release
Q2. Tizanidine produces muscle relaxation primarily by which mechanism?
- GABA-A receptor activation
- Dopamine D2 receptor antagonism
- Alpha-2 adrenergic receptor agonism in the central nervous system
- Blockade of acetylcholine receptors at the neuromuscular junction
Correct Answer: Alpha-2 adrenergic receptor agonism in the central nervous system
Q3. Diazepam reduces muscle spasm through which pharmacodynamic action?
- Direct inhibition of ryanodine receptors
- Positive allosteric modulation of GABA-A receptors
- Activation of spinal glycine receptors
- Inhibition of norepinephrine reuptake
Correct Answer: Positive allosteric modulation of GABA-A receptors
Q4. Which of the following is a centrally acting muscle relaxant rather than a peripheral one?
- Dantrolene (ryanodine receptor antagonist)
- Botulinum toxin (inhibits ACh release)
- Baclofen (GABA-B agonist)
- Local intramuscular neuromuscular blocker
Correct Answer: Baclofen (GABA-B agonist)
Q5. A notable adverse effect of tizanidine that requires monitoring during therapy is:
- Renal stones formation
- Hepatotoxicity and elevated liver enzymes
- Pulmonary fibrosis
- Severe hyperglycemia
Correct Answer: Hepatotoxicity and elevated liver enzymes
Q6. Which pharmacokinetic property is true for baclofen?
- Extensive hepatic metabolism by CYP3A4
- Primarily renal excretion unchanged
- Long half-life with active metabolites
- Eliminated via biliary excretion
Correct Answer: Primarily renal excretion unchanged
Q7. Sudden discontinuation of high-dose oral baclofen most commonly risks which complication?
- Serotonin syndrome
- Baclofen withdrawal causing hallucinations and seizures
- Progressive renal failure
- Persistent hypertension crisis
Correct Answer: Baclofen withdrawal causing hallucinations and seizures
Q8. The recommended antidote for acute benzodiazepine overdose is:
- Naloxone
- Flumazenil
- Physostigmine
- Activated charcoal only
Correct Answer: Flumazenil
Q9. Which centrally acting muscle relaxant is most associated with anticholinergic side effects and is structurally related to tricyclic antidepressants?
- Baclofen
- Tizanidine
- Cyclobenzaprine
- Methocarbamol
Correct Answer: Cyclobenzaprine
Q10. Carisoprodol’s major active metabolite that contributes to dependence is:
- Meprobamate
- Chlordiazepoxide
- Phenobarbital
- Norcarisoprodol
Correct Answer: Meprobamate
Q11. Which statement correctly contrasts centrally acting relaxants with dantrolene?
- Both act primarily at the neuromuscular junction to block ACh receptors
- Centrally acting agents act in the CNS; dantrolene acts on skeletal muscle ryanodine receptors
- Dantrolene is a GABA receptor agonist like baclofen
- Centrally acting drugs are purely peripheral and do not cross the blood‑brain barrier
Correct Answer: Centrally acting agents act in the CNS; dantrolene acts on skeletal muscle ryanodine receptors
Q12. Dantrolene’s mechanism of action involves:
- Alpha-2 adrenergic agonism
- Blocking ryanodine receptor-mediated calcium release from sarcoplasmic reticulum
- Enhancing GABAergic neurotransmission in the spinal cord
- Inhibiting acetylcholinesterase at the neuromuscular junction
Correct Answer: Blocking ryanodine receptor-mediated calcium release from sarcoplasmic reticulum
Q13. Which centrally acting muscle relaxant also has established anticonvulsant properties and is used in seizure emergencies?
- Diazepam
- Tizanidine
- Baclofen
- Methocarbamol
Correct Answer: Diazepam
Q14. For spasticity in multiple sclerosis, which oral agent is commonly first-line?
- Baclofen
- Dantrolene
- Botulinum toxin
- Carisoprodol
Correct Answer: Baclofen
Q15. Which drug interaction is particularly important with tizanidine?
- CYP1A2 inhibitors (e.g., ciprofloxacin) markedly increase tizanidine levels
- Inducers of CYP3A4 decrease tizanidine clearance
- Concurrent ACE inhibitors cause severe hyperkalemia with tizanidine
- Co-administration with metformin causes lactic acidosis
Correct Answer: CYP1A2 inhibitors (e.g., ciprofloxacin) markedly increase tizanidine levels
Q16. Combining which class of centrally acting relaxants with opioids significantly increases the risk of respiratory depression?
- Benzodiazepines
- Alpha-2 agonists like tizanidine
- Peripheral ryanodine antagonists
- Muscarinic antagonists
Correct Answer: Benzodiazepines
Q17. Which centrally acting muscle relaxant is most associated with abuse potential due to conversion to a sedative metabolite?
- Methocarbamol
- Carisoprodol
- Baclofen
- Tizanidine
Correct Answer: Carisoprodol
Q18. Intrathecal baclofen therapy is primarily indicated for:
- Mild intermittent muscle cramps
- Severe spasticity refractory to oral agents
- Acute muscle strain in athletes
- Management of myasthenia gravis
Correct Answer: Severe spasticity refractory to oral agents
Q19. Which monitoring parameter is recommended when initiating or increasing tizanidine dose?
- Serum potassium levels weekly
- Liver function tests (baseline and periodic)
- Coagulation profile monthly
- Thyroid function tests
Correct Answer: Liver function tests (baseline and periodic)
Q20. Which muscle relaxant has a long half-life with active metabolites and accumulates in elderly patients?
- Diazepam
- Tizanidine
- Baclofen
- Methocarbamol
Correct Answer: Diazepam
Q21. The analgesic component of centrally acting muscle relaxants is often due to:
- Peripheral blockade of sodium channels in muscles
- Central reduction of polysynaptic reflex activity and suppression of nociceptive transmission
- Production of anti‑inflammatory prostaglandins
- Direct regeneration of damaged muscle fibers
Correct Answer: Central reduction of polysynaptic reflex activity and suppression of nociceptive transmission
Q22. Common adverse effects shared by many centrally acting muscle relaxants include:
- Excessive salivation and hyperkinesia
- Sedation, dizziness and generalized weakness
- Marked hyperthermia and rigidity
- Severe polyuria and polydipsia
Correct Answer: Sedation, dizziness and generalized weakness
Q23. The best immediate management for severe baclofen overdose presenting with respiratory depression is:
- Rapid infusion of naloxone
- Supportive care with airway management and mechanical ventilation as needed
- Administration of flumazenil
- Forced diuresis with high-dose furosemide
Correct Answer: Supportive care with airway management and mechanical ventilation as needed
Q24. Which centrally acting muscle relaxant is contraindicated with recent MAO inhibitor use due to risk of severe interactions?
- Baclofen
- Cyclobenzaprine
- Tizanidine
- Methocarbamol
Correct Answer: Cyclobenzaprine
Q25. In emergency management of status epilepticus with associated muscle rigidity, which agent is commonly used for its anxiolytic, anticonvulsant and muscle‑relaxant effects?
- Tizanidine
- Diazepam
- Carisoprodol
- Botulinum toxin
Correct Answer: Diazepam
Q26. Baclofen exerts much of its antispastic effect at which anatomical site?
- Neuromuscular junction of peripheral muscle
- Spinal cord interneurons and presynaptic terminals
- Basal ganglia dopaminergic neurons
- Cerebellar Purkinje cells only
Correct Answer: Spinal cord interneurons and presynaptic terminals
Q27. A key contraindication or precaution for cyclobenzaprine is:
- History of narrow-angle glaucoma due to anticholinergic effects
- Severe renal hypofunction only
- Concurrent use of levodopa
- Use in patients with COPD only
Correct Answer: History of narrow-angle glaucoma due to anticholinergic effects
Q28. Which centrally acting muscle relaxant requires dose adjustment and caution in severe renal impairment?
- Baclofen
- Cyclobenzaprine
- Tizanidine
- Diazepam
Correct Answer: Baclofen
Q29. In elderly patients, which class of centrally acting muscle relaxants is most strongly associated with increased risk of falls and cognitive impairment?
- Benzodiazepines (e.g., diazepam)
- Tizanidine
- Baclofen
- Methocarbamol
Correct Answer: Benzodiazepines (e.g., diazepam)
Q30. The reduction of spasticity by baclofen is largely due to decreased release of which excitatory neurotransmitter in the spinal cord?
- Acetylcholine
- Glutamate
- Serotonin
- Glycine
Correct Answer: Glutamate
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