Direct acting parasympathomimetics – Acetylcholine MCQs With Answer

Direct acting parasympathomimetics – Acetylcholine MCQs With Answer

Direct acting parasympathomimetics, especially acetylcholine and its analogs, are central to cholinergic pharmacology taught in B. Pharm courses. This introduction covers mechanisms, receptor selectivity (muscarinic vs nicotinic), receptor subtypes (M1–M5, Nn, Nm), structure–activity relationships, pharmacokinetics, clinical uses (glaucoma, urinary retention, xerostomia), and common adverse effects. Key drugs include acetylcholine, bethanechol, carbachol, methacholine, pilocarpine and nicotine. Understanding these agents helps you predict physiological responses, contraindications (asthma, peptic ulcer), and therapeutic rationale. The following set of focused, exam-style Acetylcholine MCQs is tailored for B. Pharm students to deepen learning and improve exam readiness. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which best describes the primary action of acetylcholine when administered as a direct agonist?

• Blocks acetylcholinesterase
• Activates both muscarinic and nicotinic receptors
• Only activates muscarinic receptors
• Only activates nicotinic receptors

Correct Answer: Activates both muscarinic and nicotinic receptors

Q2. Which direct-acting parasympathomimetic is most commonly used topically to treat glaucoma?

• Bethanechol
• Pilocarpine
• Neostigmine
• Atropine

Correct Answer: Pilocarpine

Q3. Which cholinergic agonist is resistant to hydrolysis by acetylcholinesterase?

• Methacholine
• Acetylcholine
• Carbachol
• Pilocarpine

Correct Answer: Carbachol

Q4. Which direct-acting muscarinic agonist is used to stimulate bladder contraction in urinary retention?

• Bethanechol
• Pilocarpine
• Carbachol
• Nicotine

Correct Answer: Bethanechol

Q5. Which property explains why bethanechol has limited central nervous system effects?

• It is a lipophilic tertiary amine
• It is a quaternary ammonium poorly penetrating the BBB
• It is extensively metabolized by liver P450 enzymes
• It is rapidly deactivated by monoamine oxidase

Correct Answer: It is a quaternary ammonium poorly penetrating the BBB

Q6. Bronchoconstriction produced by muscarinic agonists is primarily mediated by which receptor subtype?

• M1
• M2
• M3
• M4

Correct Answer: M3

Q7. Which muscarinic receptor subtype predominates at the sinoatrial node and slows heart rate?

• M1
• M2
• M3
• M5

Correct Answer: M2

Q8. One recognized therapeutic use of acetylcholine in surgery is:

• Systemic treatment of asthma
• To induce muscle paralysis
• To produce rapid miosis during cataract surgery
• Long-term control of hypertension

Correct Answer: To produce rapid miosis during cataract surgery

Q9. Which direct-acting cholinergic agonist is approved to treat xerostomia (dry mouth) in Sjögren’s syndrome?

• Carbachol
• Methacholine
• Pilocarpine
• Bethanechol

Correct Answer: Pilocarpine

Q10. Which of the following is a common adverse effect of muscarinic agonists that limits their use in asthma patients?

• Hypertension
• Mydriasis
• Bronchospasm
• Dry mouth

Correct Answer: Bronchospasm

Q11. Which muscarinic receptor subtype is primarily responsible for stimulating exocrine gland secretions?

• M1
• M2
• M3
• M4

Correct Answer: M3

Q12. Which statement best describes bethanechol’s pharmacologic action?

• It is a muscarinic antagonist used for peptic ulcers
• It is a selective muscarinic agonist acting on urinary bladder smooth muscle
• It is a nicotinic agonist used for smoking cessation
• It inhibits acetylcholinesterase at synapses

Correct Answer: It is a selective muscarinic agonist acting on urinary bladder smooth muscle

Q13. Which cholinergic agonist is commonly used in a bronchial challenge test to diagnose airway hyperresponsiveness?

• Carbachol
• Methacholine
• Pilocarpine
• Bethanechol

Correct Answer: Methacholine

Q14. Which direct-acting agent primarily stimulates autonomic ganglia and adrenal medulla?

• Pilocarpine
• Nicotine
• Bethanechol
• Atropine

Correct Answer: Nicotine

Q15. Which structural feature is essential for classical acetylcholine-like muscarinic agonist activity?

• An aromatic ring and a tertiary alcohol
• A positively charged nitrogen and an ester separated by two carbon atoms
• A sulfhydryl group and a long alkyl chain
• A bulky lipophilic side chain and halogen atom

Correct Answer: A positively charged nitrogen and an ester separated by two carbon atoms

Q16. Which drug is most appropriate for treating postoperative urinary retention by stimulating detrusor contraction?

• Bethanechol
• Neostigmine
• Pilocarpine
• Atropine

Correct Answer: Bethanechol

Q17. Why is methacholine used diagnostically in pulmonary function testing?

• It causes bronchodilation in asthmatics
• It is a muscarinic antagonist that blocks airway receptors
• It is a muscarinic agonist causing bronchoconstriction to test hyperresponsiveness
• It acts as an acetylcholinesterase inhibitor

Correct Answer: It is a muscarinic agonist causing bronchoconstriction to test hyperresponsiveness

Q18. Which direct agonist is both muscarinic and nicotinic in action and resists breakdown by acetylcholinesterase?

• Pilocarpine
• Carbachol
• Methacholine
• Bethanechol

Correct Answer: Carbachol

Q19. Which clinical condition is a contraindication to systemic administration of muscarinic agonists?

• Peptic ulcer disease
• Asthma
• Urinary retention
• Xerostomia

Correct Answer: Asthma

Q20. Stimulation of cardiac M2 receptors produces which primary effect?

• Increased contractility
• Decrease in heart rate (negative chronotropy)
• Ventricular arrhythmias
• Systemic vasoconstriction

Correct Answer: Decrease in heart rate (negative chronotropy)

Q21. Which adverse ocular effect is least likely to occur with pilocarpine administration?

• Mydriasis
• Miosis
• Increased lacrimation
• Excessive salivation

Correct Answer: Mydriasis

Q22. How does pilocarpine produce pupillary constriction (miosis)?

• Inhibition of adrenergic receptors on the iris dilator
• Contraction of sphincter pupillae via M3 receptors
• Stimulation of sympathetic ganglia innervating the iris
• Blockade of acetylcholinesterase around the pupil

Correct Answer: Contraction of sphincter pupillae via M3 receptors

Q23. Which drug is used to stimulate salivary flow in radiation-induced xerostomia?

• Methacholine
• Pilocarpine
• Carbachol
• Neostigmine

Correct Answer: Pilocarpine

Q24. Which direct-acting parasympathomimetic is a tertiary amine and can cross the blood–brain barrier?

• Bethanechol
• Carbachol
• Pilocarpine
• Neostigmine

Correct Answer: Pilocarpine

Q25. Which of the following agents primarily stimulates autonomic ganglia and is used in smoking research and cessation therapies?

• Bethanechol
• Pilocarpine
• Nicotine
• Carbachol

Correct Answer: Nicotine

Q26. Which direct-acting cholinergic agonist is effective in lowering intraocular pressure by contracting the ciliary muscle?

• Bethanechol
• Carbachol
• Nicotine
• Morphine

Correct Answer: Carbachol

Q27. Why is acetylcholine seldom used therapeutically for systemic indications?

• It has extensive oral bioavailability
• It is rapidly hydrolyzed by acetylcholinesterase
• It selectively activates only M1 receptors
• It causes permanent receptor desensitization

Correct Answer: It is rapidly hydrolyzed by acetylcholinesterase

Q28. Which direct-acting cholinergic drug has a longer duration of action and is effective in treating urinary retention?

• Acetylcholine
• Methacholine
• Bethanechol
• Pilocarpine

Correct Answer: Bethanechol

Q29. At the neuromuscular junction, acetylcholine causes which immediate event?

• Inhibition of sodium channels
• Depolarization of motor endplate leading to muscle contraction
• Blockade of nicotinic receptors
• Activation of muscarinic receptors on skeletal muscle

Correct Answer: Depolarization of motor endplate leading to muscle contraction

Q30. Administration of muscarinic agonists is relatively contraindicated in patients with which condition?

• Glaucoma (open-angle)
• Peptic ulcer disease
• Urinary retention
• Dry mouth

Correct Answer: Peptic ulcer disease

Q31. Which muscarinic receptor subtype is most closely associated with cognitive function in the central nervous system?

• M2
• M3
• M1
• M4

Correct Answer: M1

Q32. How can you pharmacologically distinguish muscarinic from nicotinic cholinergic effects?

• Use of hexamethonium to block muscarinic receptors
• Administration of atropine abolishes muscarinic but not nicotinic responses
• Use of atropine specifically blocks nicotinic receptors
• Acetylcholinesterase inhibitors selectively block muscarinic effects

Correct Answer: Administration of atropine abolishes muscarinic but not nicotinic responses

Q33. Why do quaternary ammonium cholinergic agonists have poor central nervous system penetration?

• Their large aromatic rings impede transport
• They are highly lipophilic and sequestered in fat
• Permanent positive charge prevents crossing lipid membranes
• They are substrates for P-glycoprotein efflux in the BBB

Correct Answer: Permanent positive charge prevents crossing lipid membranes

Q34. In acute angle-closure glaucoma, which direct-acting cholinergic agonist can be used to induce miosis and open the trabecular meshwork?

• Pilocarpine
• Bethanechol
• Methacholine
• Propranolol

Correct Answer: Pilocarpine

Q35. Which muscarinic receptor subtype mediates gastric acid secretion on parietal cells?

• M1
• M2
• M3
• M5

Correct Answer: M3

Q36. Which drug can stimulate sweating (via sympathetic cholinergic fibers) and is used diagnostically in sweat testing?

• Pilocarpine
• Carbachol
• Bethanechol
• Morphine

Correct Answer: Pilocarpine

Q37. Which muscarinic receptor subtype is coupled to Gi proteins and inhibits adenylate cyclase?

• M1
• M2
• M3
• M4

Correct Answer: M2

Q38. Muscarinic agonist–induced vasodilation in intact blood vessels is mediated by which mechanism?

• Direct relaxation of vascular smooth muscle M2 receptors
• Endothelial M3 receptor–mediated nitric oxide release
• Activation of sympathetic adrenergic receptors
• Blockade of calcium channels in smooth muscle

Correct Answer: Endothelial M3 receptor–mediated nitric oxide release

Q39. Which statement correctly contrasts carbachol with acetylcholine?

• Carbachol is more rapidly hydrolyzed than acetylcholine
• Carbachol is less susceptible to cholinesterase and activates both muscarinic and nicotinic receptors
• Carbachol is a muscarinic antagonist
• Carbachol cannot be used in ophthalmic applications

Correct Answer: Carbachol is less susceptible to cholinesterase and activates both muscarinic and nicotinic receptors

Q40. Which agent is the drug of choice for diagnostic methacholine challenge testing for bronchial hyperreactivity?

• Acetylcholine
• Methacholine
• Pilocarpine
• Bethanechol

Correct Answer: Methacholine

Q41. Which direct-acting cholinergic agonist is considered relatively selective for muscarinic receptors with minimal nicotinic activity?

• Carbachol
• Bethanechol
• Nicotine
• Suxamethonium

Correct Answer: Bethanechol

Q42. Which structural modification of acetylcholine analogs increases resistance to acetylcholinesterase hydrolysis?

• Introduction of a carbamate ester replacing the acetyl group
• Addition of an aromatic benzene ring
• Converting the tertiary amine to a quaternary ammonium
• Removal of the ester linkage entirely

Correct Answer: Introduction of a carbamate ester replacing the acetyl group

Q43. Which mnemonic correctly represents common muscarinic excess symptoms (SLUDGE)?

• Somnolence, Lethargy, Urination, Diaphoresis, Gastrointestinal pain, Emesis
• Salivation, Lacrimation, Urination, Diarrhea, Gastrointestinal upset, Emesis
• Sweating, Lightheadedness, Urgency, Dry mouth, Gastric stasis, Emesis
• Seizures, Lethargy, Urination, Dyspnea, Glaucoma, Edema

Correct Answer: Salivation, Lacrimation, Urination, Diarrhea, Gastrointestinal upset, Emesis

Q44. Contraction of the ciliary muscle by muscarinic agonists produces which visual change?

• Relaxation for distant vision
• Contraction producing near vision (accommodation)
• Loss of accommodation
• Permanent mydriasis

Correct Answer: Contraction producing near vision (accommodation)

Q45. Which receptor mediates fast excitatory transmission in autonomic ganglia?

• Muscarinic M2
• Nicotinic Nn (neuronal)
• M3 muscarinic
• Beta-adrenergic

Correct Answer: Nicotinic Nn (neuronal)

Q46. Which drug is preferred to stimulate bladder emptying with minimal systemic vascular effects?

• Bethanechol
• Acetylcholine
• Pilocarpine
• Methacholine

Correct Answer: Bethanechol

Q47. Which direct-acting muscarinic agonist is used both in glaucoma therapy and to stimulate salivary secretion?

• Carbachol
• Pilocarpine
• Bethanechol
• Methacholine

Correct Answer: Pilocarpine

Q48. Excessive stimulation of cardiac M2 receptors can lead to which conduction abnormality?

• Ventricular fibrillation
• AV block
• Hypertrophic cardiomyopathy
• Atrial septal defect

Correct Answer: AV block

Q49. Which muscarinic agonist is used in pilocarpine iontophoresis to induce sweat for cystic fibrosis testing?

• Pilocarpine
• Carbachol
• Bethanechol
• Neostigmine

Correct Answer: Pilocarpine

Q50. Which direct-acting agent is commonly applied topically to the eye because it resists acetylcholinesterase and produces sustained miosis?

• Methacholine
• Carbachol
• Acetylcholine
• Pilocarpine

Correct Answer: Carbachol

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