Introduction: Atropine is a classic tropane alkaloid central to B.Pharm pharmacology and medicinal chemistry. This concise, student-focused review highlights atropine’s classification as a tertiary muscarinic antagonist, natural sources (Atropa belladonna, Datura), chemical structure (tropane ester of tropic acid), pharmacodynamics and pharmacokinetics, mechanism of action at M1–M5 receptors, clinical pharmacotherapy (preanesthetic medication, ophthalmic mydriasis and cycloplegia, symptomatic bradycardia, antidote in organophosphate poisoning), adverse effects and toxicology (anticholinergic syndrome, contraindication in narrow‑angle glaucoma), drug interactions, and important derivatives (scopolamine, glycopyrrolate). Clear, exam‑oriented keywords and focused points will strengthen revision. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What chemical class does atropine belong to?
- Tropane alkaloid
- Isoquinoline alkaloid
- Indole alkaloid
- Pyrrolizidine alkaloid
Correct Answer: Tropane alkaloid
Q2. Which plant is a primary natural source of atropine?
- Atropa belladonna
- Digitalis purpurea
- Cinchona officinalis
- Rauwolfia serpentina
Correct Answer: Atropa belladonna
Q3. What is the primary mechanism of action of atropine?
- Competitive muscarinic receptor antagonist
- Non‑competitive nicotinic receptor antagonist
- Acetylcholinesterase inhibitor
- Beta‑adrenergic agonist
Correct Answer: Competitive muscarinic receptor antagonist
Q4. Atropine blocks which receptor subtypes?
- Muscarinic M1–M5 receptors
- Only M2 receptors
- Only M3 receptors
- Nicotinic skeletal muscle receptors
Correct Answer: Muscarinic M1–M5 receptors
Q5. Which ocular effect is characteristic of atropine?
- Mydriasis and cycloplegia
- Miosis and accommodation spasm
- Conjunctival vasoconstriction only
- No effect on pupil size
Correct Answer: Mydriasis and cycloplegia
Q6. Atropine is indicated as an emergency treatment for which cardiovascular condition?
- Symptomatic bradycardia
- Essential hypertension
- Atrial fibrillation with rapid ventricular response
- Acute myocardial ischemia as first‑line therapy
Correct Answer: Symptomatic bradycardia
Q7. In organophosphate poisoning, atropine is used primarily to:
- Reverse muscarinic overstimulation
- Reactivate acetylcholinesterase enzyme
- Enhance nicotinic receptor transmission
- Chelate organophosphate compounds
Correct Answer: Reverse muscarinic overstimulation
Q8. Does atropine readily cross the blood–brain barrier?
- Yes — it is a tertiary amine and crosses the BBB
- No — it is a quaternary ammonium compound and cannot cross
- Only when given intrathecally
- Only in neonates
Correct Answer: Yes — it is a tertiary amine and crosses the BBB
Q9. What is the effect of atropine on salivary secretions?
- Marked reduction of salivation (antisialagogue)
- Increased salivation
- No change in salivary flow
- Transient increase followed by decrease
Correct Answer: Marked reduction of salivation (antisialagogue)
Q10. How does atropine affect gastrointestinal motility?
- Decreases motility and secretions, causing constipation
- Increases motility and secretions, causing diarrhea
- No significant effect on GI function
- Only affects gastric acid secretion without motility change
Correct Answer: Decreases motility and secretions, causing constipation
Q11. Atropine is contraindicated in which of the following conditions?
- Acute narrow‑angle glaucoma
- Hypothyroidism
- Hypotension due to hemorrhage
- Type 1 diabetes mellitus
Correct Answer: Acute narrow‑angle glaucoma
Q12. Which drug is the antidote of choice for severe central and peripheral atropine toxicity?
- Physostigmine
- Neostigmine
- Propranolol
- Naloxone
Correct Answer: Physostigmine
Q13. The principal cardiac effect of therapeutic doses of atropine is:
- Tachycardia due to vagal blockade
- Bradycardia due to direct SA node suppression
- Increased AV conduction block
- No effect on heart rate
Correct Answer: Tachycardia due to vagal blockade
Q14. How does atropine affect sweating and thermoregulation?
- Reduces sweating leading to potential hyperthermia
- Increases sweating and causes hypothermia
- No effect on eccrine glands
- Only affects thermoregulation in infants
Correct Answer: Reduces sweating leading to potential hyperthermia
Q15. The mydriatic and cycloplegic effect of topical atropine eye drops typically lasts for:
- Up to 7–10 days
- 12–24 hours
- 1–2 hours
Correct Answer: Up to 7–10 days
Q16. Which pharmacokinetic property best describes atropine?
- Well absorbed orally and widely distributed; crosses placenta and BBB
- Poorly absorbed orally and restricted to plasma
- Exclusively excreted unchanged in bile
- Only administered parenterally due to complete first‑pass inactivation
Correct Answer: Well absorbed orally and widely distributed; crosses placenta and BBB
Q17. In preanesthetic medication, atropine is used primarily to:
- Reduce respiratory and salivary secretions and prevent vagal reflexes
- Induce analgesia
- Enhance skeletal muscle relaxation
- Reduce risk of malignant hyperthermia
Correct Answer: Reduce respiratory and salivary secretions and prevent vagal reflexes
Q18. Which related alkaloid is commonly used for prevention of motion sickness and as an antiemetic?
- Scopolamine (hyoscine)
- Quinine
- Reserpine
- Atropine methyl bromide
Correct Answer: Scopolamine (hyoscine)
Q19. Which antimuscarinic agent is a quaternary ammonium compound and does not readily cross the blood–brain barrier?
- Glycopyrrolate
- Atropine
- Scopolamine
- Tropicamide
Correct Answer: Glycopyrrolate
Q20. Classic features of atropine (anticholinergic) poisoning include:
- Hot, dry, flushed skin; delirium; mydriasis
- Excessive salivation, miosis, bradycardia
- Profuse sweating and pulmonary edema
- Hypotension and pinpoint pupils
Correct Answer: Hot, dry, flushed skin; delirium; mydriasis
Q21. Atropine’s effect on the bronchial tree includes:
- Bronchodilation and reduced bronchial secretions
- Bronchoconstriction and increased secretions
- No effect on bronchial smooth muscle
- Increased bronchial mucus viscosity without tone change
Correct Answer: Bronchodilation and reduced bronchial secretions
Q22. How does atropine affect the urinary bladder?
- Causes urinary retention by relaxing detrusor and increasing sphincter tone
- Promotes micturition by contracting detrusor muscle
- No significant urinary effects
- Increases bladder contractions and frequency
Correct Answer: Causes urinary retention by relaxing detrusor and increasing sphincter tone
Q23. Blockade of which muscarinic receptor subtype by atropine contributes most to tachycardia?
- M2 receptor
- M1 receptor
- M3 receptor
- M4 receptor
Correct Answer: M2 receptor
Q24. Which statement about atropine in organophosphate poisoning is correct?
- Atropine relieves muscarinic symptoms but does not reverse nicotinic neuromuscular blockade
- Atropine reactivates acetylcholinesterase
- Atropine directly detoxifies organophosphates
- Atropine is contraindicated in organophosphate poisoning
Correct Answer: Atropine relieves muscarinic symptoms but does not reverse nicotinic neuromuscular blockade
Q25. Which class of drugs can potentiate the anticholinergic effects of atropine?
- Tricyclic antidepressants
- Beta‑blockers
- Cholinesterase inhibitors
- ACE inhibitors
Correct Answer: Tricyclic antidepressants
Q26. Low doses of atropine may paradoxically produce which effect?
- Transient bradycardia due to blockade of presynaptic inhibitory muscarinic receptors
- Sustained hypertension due to sympathetic stimulation
- Profuse sweating due to cholinergic overactivity
- Immediate mydriasis without systemic effects
Correct Answer: Transient bradycardia due to blockade of presynaptic inhibitory muscarinic receptors
Q27. The characteristic structural feature of atropine is:
- Tropane ring esterified with tropic acid (tropane ester)
- Benzylisoquinoline backbone
- Indole nucleus with tryptamine side chain
- Macrocyclic lactone ring
Correct Answer: Tropane ring esterified with tropic acid (tropane ester)
Q28. Beyond mydriasis, atropine is clinically useful in ophthalmology for:
- Treatment of anterior uveitis to relieve ciliary spasm and prevent posterior synechiae
- Treatment of bacterial conjunctivitis as an antibiotic
- Lowering intraocular pressure in glaucoma
- Stimulating lacrimation in dry eye syndrome
Correct Answer: Treatment of anterior uveitis to relieve ciliary spasm and prevent posterior synechiae
Q29. The principal routes for atropine elimination involve:
- Hepatic metabolism with renal excretion of metabolites
- Excretion unchanged exclusively in feces
- Complete pulmonary elimination
- Renal excretion as unchanged drug only
Correct Answer: Hepatic metabolism with renal excretion of metabolites
Q30. A clinical sign strongly suggestive of atropine overdose is:
- Fixed, dilated pupils unreactive to light
- Pinpoint reactive pupils
- Brisk pupillary light reflex with miosis
- Rapidly alternating anisocoria with constriction
Correct Answer: Fixed, dilated pupils unreactive to light
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