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Pharmacology MCQ practice

Autonomic Pharmacology MCQ Practice

Review adrenergic, cholinergic, antimuscarinic, neuromuscular, and autonomic toxicology questions.

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Sample Questions

Adrenergics

Methyldopa lowers BP after conversion to alpha-methylnoradrenaline. Which action belongs to monoamine oxidase?

  • Activates monoamine *oxidase*
  • Forms a false transmitter
  • Stimulates central alpha-2 receptors
  • Reduces sympathetic outflow

Answer: Activates monoamine *oxidase*

Monoamine oxidase metabolises monoamines; activating it is not methyldopa's central antihypertensive mechanism.

Methyldopa forms alpha-methylnoradrenaline, stimulates central alpha-2 receptors, and reduces sympathetic outflow.

Adrenergics

Which classification best describes Methyldopa results in the formation of methylnoradrenaline which?

  • False transmitter
  • Alpha adrenoceptor agonist
  • Beta adrenoceptor agonist
  • Tyrosine hydroxylase inhibitor

Answer: False transmitter

Methyldopa is converted to alpha-methylnoradrenaline, a false transmitter that reduces sympathetic outflow mainly through central alpha-2 agonism.

It is not primarily a beta agonist or tyrosine hydroxylase inhibitor; alpha agonist activity is relevant but less precise than false transmitter here.

Adrenergics

Postural hypotension in a patient prescribed an alpha-1 adrenoceptor antagonist is likely to be worst

  • After three days
  • After three months
  • After the first dose
  • After three weeks

Answer: After the first dose

Alpha-1 antagonists can cause first-dose postural hypotension because sudden venodilation reduces venous return before compensation develops.

Tolerance to the first-dose effect often develops, so symptoms are usually less likely after days, weeks, or months of stable dosing.

Adrenergics

Labetalol is a nonselective beta blocker with some alpha antagonism. It may be preferable to propranolol in patients with

  • Asthma or COPD
  • Peripheral vascular disease
  • Urinary incontinence
  • Nasal congestion

Answer: Peripheral vascular disease

Labetalol has alpha-blocking vasodilator activity, which may make it preferable to propranolol when peripheral vascular disease is a concern.

Asthma remains a caution with nonselective beta blockade, while urinary incontinence and nasal congestion are not reasons to prefer labetalol.

Cholinergics

In patients with pseudocholinesterase deficiency, administration of suxamethonium (succinylcholine) may result in which of the following?

  • Bronchospasm
  • Prolonged apnoea
  • Malignant hyperthermia
  • Blepharospasm

Answer: Prolonged apnoea

Pseudocholinesterase deficiency slows suxamethonium metabolism, causing prolonged paralysis and apnoea.

Bronchospasm and blepharospasm are unrelated; malignant hyperthermia is a separate pharmacogenetic susceptibility.

Cholinergics

Patients with organophosphate poisoning present with bradycardia due to ________ of cardiac ____ receptors. The blanks are

  • Inhibition / M3
  • Activation / M2
  • Activation / M3
  • Inhibition / M2

Answer: Activation / M2

Organophosphate poisoning raises acetylcholine, activating cardiac M2 receptors and causing bradycardia.

M3 receptors mediate gland and smooth muscle effects; inhibition of muscarinic receptors would not explain cholinergic bradycardia.

Learning Design

Drugzzle uses brief single-best-answer rounds, immediate feedback, confidence reflection, and missed-question review to support retrieval practice and safer prescribing reasoning.