Autonomic pharmacology: sympathomimetics and sympatholytics MCQs With Answer

Autonomic pharmacology: sympathomimetics and sympatholytics MCQs With Answer is designed for M.Pharm students aiming to deepen understanding of adrenergic pharmacology at an advanced level. This collection emphasizes receptor pharmacodynamics, drug-receptor selectivity, clinical applications, adverse effects, and molecular mechanisms such as agonism, antagonism, partial agonists and inverse agonists. Questions integrate therapeutic scenarios—hypertension, heart failure, asthma, shock, pheochromocytoma—and cover pharmacokinetics, tolerance, and drug interactions. Each MCQ is crafted to encourage critical thinking required for postgraduate pharmacology exams and rational therapeutic design. Answers are provided to facilitate self-assessment and focused revision for advanced clinical and research roles.

Q1. Which sympathomimetic agent is a selective beta-2 agonist commonly used as a bronchodilator with minimal cardiac beta-1 stimulation at therapeutic doses?

• Isoproterenol
• Dobutamine
• Salbutamol (albuterol)
• Phenylephrine

Correct Answer: Salbutamol (albuterol)

Q2. A patient with pheochromocytoma requires preoperative blood pressure control to prevent hypertensive crises. Which drug is the best choice for irreversible alpha-adrenergic blockade prior to surgery?

• Prazosin
• Phentolamine
• Phenoxybenzamine
• Propranolol

Correct Answer: Phenoxybenzamine

Q3. Which mechanism best explains the antihypertensive effect of clonidine?

• Peripheral alpha-1 blockade causing vasodilation
• Central alpha-2 agonism reducing sympathetic outflow
• Beta-1 blockade decreasing cardiac output
• Alpha-2 antagonism increasing baroreceptor sensitivity

Correct Answer: Central alpha-2 agonism reducing sympathetic outflow

Q4. Which sympathomimetic increases release of norepinephrine from nerve terminals and is also used as an appetite suppressant?

• Amphetamine
• Ephedrine
• Cocaine
• Clonidine

Correct Answer: Amphetamine

Q5. Which beta-blocker has intrinsic sympathomimetic activity (partial agonist) and is preferred in patients with bradycardia?

• Metoprolol
• Pindolol
• Propranolol
• Atenolol

Correct Answer: Pindolol

Q6. A drug that causes vasoconstriction via alpha-1 receptors and is frequently used as a nasal decongestant is:

• Clonidine
• Phenylephrine
• Isoproterenol
• Terbutaline

Correct Answer: Phenylephrine

Q7. Which sympatholytic agent is a nonselective beta-blocker with high lipid solubility and is effective in migraine prophylaxis?

• Propranolol
• Nadolol
• Metoprolol
• Timolol

Correct Answer: Propranolol

Q8. Which drug is a selective alpha-1 blocker used for long-term management of hypertension and also improves urinary flow in benign prostatic hyperplasia?

• Prazosin
• Phentolamine
• Phenoxybenzamine
• Reserpine

Correct Answer: Prazosin

Q9. Which agent is a mixed alpha and beta agonist used in anaphylactic shock to increase peripheral resistance and cardiac output?

• Norepinephrine
• Isoproterenol
• Epinephrine
• Dobutamine

Correct Answer: Epinephrine

Q10. A patient on a monoamine oxidase inhibitor (MAOI) eats tyramine-rich foods and develops a hypertensive crisis. Which mechanism explains this reaction?

• Tyramine inhibits catecholamine synthesis
• Tyramine displaces norepinephrine from nerve terminals causing massive release
• Tyramine directly stimulates alpha-2 receptors centrally
• Tyramine increases COMT degradation of catecholamines

Correct Answer: Tyramine displaces norepinephrine from nerve terminals causing massive release

Q11. Which pharmacological property distinguishes a partial agonist at beta receptors from a full agonist?

• Produces maximal response regardless of receptor density
• Produces lower intrinsic activity even when occupying all receptors
• Acts as a competitive antagonist in presence of inverse agonists only
• Causes irreversible receptor activation

Correct Answer: Produces lower intrinsic activity even when occupying all receptors

Q12. Which drug is an alpha-2 antagonist that may increase sympathetic tone and is occasionally used to reverse central alpha-2 agonist effects?

• Yohimbine
• Clonidine
• Methyldopa
• Guanethidine

Correct Answer: Yohimbine

Q13. Which sympathomimetic is primarily used as an inotropic agent in cardiogenic shock because of potent beta-1 activity with modest beta-2 and alpha effects?

• Dobutamine
• Phenylephrine
• Terbutaline
• Epinephrine

Correct Answer: Dobutamine

Q14. Which adverse effect is most characteristic of nonselective beta-blockers in patients with asthma?

• Bronchoconstriction due to beta-2 blockade
• Excessive peripheral vasodilation
• Increased aqueous humor production
• Alpha-1 receptor hypersensitivity

Correct Answer: Bronchoconstriction due to beta-2 blockade

Q15. Reserpine decreases sympathetic transmission by which primary mechanism?

• Competitive blockade of alpha receptors
• Inhibition of monoamine oxidase
• Irreversible inhibition of vesicular monoamine transporter (VMAT) leading to depletion of catecholamines
• Enhancement of norepinephrine synthesis

Correct Answer: Irreversible inhibition of vesicular monoamine transporter (VMAT) leading to depletion of catecholamines

Q16. Which drug selectively inhibits catechol-O-methyltransferase (COMT) and is used as an adjunct in Parkinson’s disease, also relevant to catecholamine metabolism?

• Entacapone
• Selegiline
• Moclobemide
• Phenelzine

Correct Answer: Entacapone

Q17. In treating hypertensive emergency due to catecholamine excess, which intravenous drug offers rapid alpha-1 blockade and short duration suitable for titration?

• Phenoxybenzamine
• Nifedipine
• Phentolamine
• Prazosin

Correct Answer: Phentolamine

Q18. Which beta-blocker is highly selective for beta-1 receptors and preferred in patients with chronic obstructive pulmonary disease (COPD) when a beta-blocker is required?

• Atenolol
• Propranolol
• Carvedilol
• Pindolol

Correct Answer: Atenolol

Q19. Which drug is an indirect sympathomimetic that acts primarily by inhibiting norepinephrine reuptake and is used as an antidepressant as well as for neuropathic pain?

• Desipramine
• Ephedrine
• Phenylephrine
• Clonidine

Correct Answer: Desipramine

Q20. Which phenomenon explains rapid loss of vasopressor response during continuous infusion of a direct alpha agonist due to receptor regulation?

• Upregulation of receptor number
• Pharmacokinetic tolerance due to increased clearance only
• Receptor desensitization and downregulation
• Enhanced second messenger signaling

Correct Answer: Receptor desensitization and downregulation

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