Introduction: Myasthenia gravis is an autoimmune neuromuscular disorder marked by fatigable muscle weakness due to antibodies against the acetylcholine receptor (AChR) or related proteins. Understanding pharmacology—acetylcholinesterase inhibitors (pyridostigmine, neostigmine), immunosuppressants (corticosteroids, azathioprine, mycophenolate), biologics (rituximab, eculizumab), and supportive therapies (IVIG, plasmapheresis)—is essential for B. Pharm students. Key concepts include mechanism of action, onset and duration, adverse effects, drug interactions, and perioperative management. Mastery of these drugs informs safe dispensing, counselling, and monitoring. This set emphasizes clinical relevance, pharmacokinetics, and exam-style reasoning. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which drug is the first-line symptomatic treatment for generalized myasthenia gravis to improve neuromuscular transmission?
- Pyridostigmine
Correct Answer: Pyridostigmine
Q2. What is the primary mechanism of action of neostigmine in myasthenia gravis?
- Direct agonist at nicotinic acetylcholine receptors
- Inhibition of acetylcholinesterase enzyme
- Blockade of complement activation
- B-cell depletion via CD20 binding
Correct Answer: Inhibition of acetylcholinesterase enzyme
Q3. Which immunosuppressant is commonly used as a steroid-sparing agent in long-term management of myasthenia gravis?
Correct Answer: Azathioprine
Q4. Which monoclonal antibody targets the complement protein C5 and is approved for refractory AChR-positive generalized myasthenia gravis?
Correct Answer: Eculizumab
Q5. Which test historically used short-acting acetylcholinesterase inhibition to transiently improve muscle strength and aid diagnosis of myasthenia gravis?
Correct Answer: Both Edrophonium test and Tensilon test
Q6. A cholinergic crisis due to excess acetylcholinesterase inhibitor presents with which prominent sign that helps distinguish it from myasthenic crisis?
- Worsening muscle weakness only
- Excessive salivation and sweating
- Improved muscle strength after edrophonium
- Isolated ocular symptoms
Correct Answer: Excessive salivation and sweating
Q7. Which antibiotic class is known to potentially worsen myasthenia gravis and should be used with caution?
Correct Answer: Aminoglycosides
Q8. Which drug is most appropriate for rapid short-term removal of pathogenic antibodies during a myasthenic crisis?
Correct Answer: Plasmapheresis
Q9. Which adverse effect is most commonly associated with long-term high-dose corticosteroid therapy in myasthenia gravis?
- Osteoporosis and hyperglycemia
- Increased acetylcholine release
- Renal failure
- Peripheral neuropathy
Correct Answer: Osteoporosis and hyperglycemia
Q10. Which antibody is most commonly detected in generalized adult myasthenia gravis?
- MuSK antibody
- AChR (acetylcholine receptor) antibody
- LRP4 antibody
- Anti-dsDNA antibody
Correct Answer: AChR (acetylcholine receptor) antibody
Q11. Which agent is preferred in pregnancy for symptomatic control of myasthenia gravis because of relative safety and established use?
Correct Answer: Pyridostigmine
Q12. Which of the following is a key monitoring parameter for a patient on azathioprine?
- Liver function tests and complete blood count
- Serum acetylcholine levels
- Urine protein electrophoresis
- Serial thyroid function tests
Correct Answer: Liver function tests and complete blood count
Q13. Rituximab exerts its therapeutic effect in some myasthenia gravis patients by which mechanism?
- Complement inhibition at C5
- Depletion of CD20-positive B cells
- Blockade of acetylcholine receptors
- Direct stimulation of nicotinic receptors
Correct Answer: Depletion of CD20-positive B cells
Q14. Which drug is contraindicated in pregnant women with myasthenia gravis due to teratogenicity?
Correct Answer: Mycophenolate mofetil
Q15. What is the main pharmacodynamic difference between pyridostigmine and edrophonium?
Correct Answer: Pyridostigmine is long-acting; edrophonium is short-acting
Q16. Which therapy provides pooled immunoglobulins and is used for rapid short-term improvement in myasthenic crisis?
Correct Answer: Intravenous immunoglobulin (IVIG)
Q17. Which receptor subtype is directly affected in congenital myasthenic syndromes distinct from autoimmune MG?
- Nicotinic acetylcholine receptor subunit mutations
- Muscarinic M2 receptor overactivity
- Dopamine D2 receptor mutation
Correct Answer: Nicotinic acetylcholine receptor subunit mutations
Q18. Which class of drugs should be avoided or used cautiously because they can exacerbate myasthenia gravis by impairing neuromuscular transmission?
- Beta blockers and certain calcium channel blockers
Correct Answer: Beta blockers and certain calcium channel blockers
Q19. What is a distinguishing feature of MuSK-antibody positive myasthenia gravis compared with AChR-positive disease?
- More prominent bulbar and respiratory weakness and poorer response to pyridostigmine
- Better response to cholinesterase inhibitors
- Always associated with thymoma
- Only affects children
Correct Answer: More prominent bulbar and respiratory weakness and poorer response to pyridostigmine
Q20. Which perioperative consideration is most important for a myasthenia gravis patient undergoing anesthesia?
- Avoid or carefully titrate neuromuscular blocking agents and monitor respiratory function
Correct Answer: Avoid or carefully titrate neuromuscular blocking agents and monitor respiratory function
Q21. Which of the following best describes the goal of long-term therapy with corticosteroids in myasthenia gravis?
- Rapid antibody removal in hours
- Immunosuppression to reduce autoantibody production
- Direct enhancement of neuromuscular transmission
- Immediate reversal of a cholinergic crisis
Correct Answer: Immunosuppression to reduce autoantibody production
Q22. Which monitoring is important for a patient receiving eculizumab therapy?
- Vaccination status for Neisseria meningitidis prior to treatment
- Serum acetylcholinesterase activity weekly
- Daily complete blood counts
- Routine creatine kinase for muscle breakdown
Correct Answer: Vaccination status for Neisseria meningitidis prior to treatment
Q23. Which therapeutic option is preferred for rapid immunomodulation in severe myasthenic exacerbation when plasmapheresis is not available?
Correct Answer: Intravenous immunoglobulin (IVIG)
Q24. Which drug interaction is clinically significant in a patient taking pyridostigmine?
- Concomitant use of aminoglycosides increasing neuromuscular blockade
- Statins increasing pyridostigmine clearance
- Proton pump inhibitors enhancing pyridostigmine absorption
- Antacids causing pyridostigmine toxicity
Correct Answer: Concomitant use of aminoglycosides increasing neuromuscular blockade
Q25. What is a common early cholinergic side effect of acetylcholinesterase inhibitors that students should counsel patients about?
- Gastrointestinal cramps and diarrhea
- Hair loss
- Renal colic
- Hyperreflexia
Correct Answer: Gastrointestinal cramps and diarrhea
Q26. Which statement about thymectomy in myasthenia gravis is correct?
- Thymectomy may benefit patients with thymoma or early generalized AChR-positive MG
- Thymectomy is first-line for MuSK-positive MG in all cases
- Thymectomy cures congenital myasthenic syndromes
- Thymectomy must be performed in all ocular MG patients
Correct Answer: Thymectomy may benefit patients with thymoma or early generalized AChR-positive MG
Q27. Which pharmacokinetic property of pyridostigmine affects its dosing schedule?
- Relatively short half-life requiring multiple daily dosing
- Extensive hepatic metabolism permitting once-weekly dosing
- Depot formation allowing monthly injections
- High lipid solubility leading to accumulation in adipose tissue
Correct Answer: Relatively short half-life requiring multiple daily dosing
Q28. In neonatal myasthenia gravis due to transplacental antibodies, what is the usual course and mainstay of treatment?
- Transient weakness managed supportively and with anticholinesterases if needed
- Permanent weakness requiring lifelong immunosuppression
- Immediate thymectomy in the neonate
- Treatment with eculizumab in all cases
Correct Answer: Transient weakness managed supportively and with anticholinesterases if needed
Q29. Which laboratory or electrophysiological test supports the diagnosis of myasthenia gravis by showing decremental response to repetitive stimulation?
- Repetitive nerve stimulation (RNS) study
Correct Answer: Repetitive nerve stimulation (RNS) study
Q30. Which agent used in other autoimmune disorders is contraindicated in women planning pregnancy and should be avoided in women with MG who wish to conceive?
Correct Answer: Methotrexate
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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