Mixed acting agents – Metaraminol MCQs With Answer

Mixed acting agents – Metaraminol MCQs With Answer

Metaraminol is a mixed-acting vasopressor frequently covered in B. Pharm pharmacology modules. This introduction outlines its mechanism as a predominantly alpha‑adrenergic agonist that also releases norepinephrine, clinical applications for acute intraoperative and neurogenic hypotension, pharmacokinetics influenced by MAO metabolism, dose forms and common adverse effects such as hypertension and reflex bradycardia. Understanding metaraminol helps B. Pharm students link receptor pharmacology, drug interactions (MAOIs, TCAs), and safe IV administration. These MCQs focus on mechanism, dosing, monitoring, stability, contraindications and clinical comparisons with other vasopressors to reinforce applied knowledge for exams and clinical practice. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What best defines a “mixed acting” sympathomimetic agent?

• An agent that acts only on alpha receptors
• An agent that acts only on beta receptors
• An agent that exerts direct receptor agonism and indirectly releases endogenous catecholamines
• An agent that blocks adrenergic receptors

Correct Answer: An agent that exerts direct receptor agonism and indirectly releases endogenous catecholamines

Q2. Metaraminol is classified pharmacologically as:

• A selective beta-2 agonist
• A mixed-acting sympathomimetic with predominant alpha‑1 activity
• A pure indirect sympathomimetic that only releases norepinephrine
• An acetylcholinesterase inhibitor

Correct Answer: A mixed-acting sympathomimetic with predominant alpha‑1 activity

Q3. The primary mechanism by which metaraminol increases blood pressure is:

• Direct beta-2 mediated vasodilation
• Direct alpha-1 receptor stimulation and displacement of norepinephrine from storage vesicles
• Inhibition of angiotensin converting enzyme
• Blocking muscarinic receptors in blood vessels

Correct Answer: Direct alpha-1 receptor stimulation and displacement of norepinephrine from storage vesicles

Q4. The most common clinical indication for metaraminol is:

• Treatment of chronic hypertension
• Acute intraoperative or spinal anaesthesia-induced hypotension
• Management of bronchospasm in asthma
• Long-term heart failure therapy

Correct Answer: Acute intraoperative or spinal anaesthesia-induced hypotension

Q5. Typical onset and duration after an IV bolus of metaraminol are:

• Onset 30–60 minutes; duration 12–24 hours
• Onset 1–2 minutes; duration approximately 20–60 minutes
• Onset immediate; duration 5–10 seconds
• Onset 24 hours; duration days

Correct Answer: Onset 1–2 minutes; duration approximately 20–60 minutes

Q6. Which routes of administration are commonly used for metaraminol?

• Oral tablet once daily
• Intramuscular injection only
• Intravenous bolus or continuous IV infusion
• Topical application to mucous membranes

Correct Answer: Intravenous bolus or continuous IV infusion

Q7. Metaraminol’s receptor activity profile includes:

• Predominant beta-2 agonism with no alpha effect
• Predominant alpha-1 agonism, some alpha-2 activity, minimal beta activity
• Pure muscarinic agonism
• Pure dopamine D2 receptor agonism

Correct Answer: Predominant alpha-1 agonism, some alpha-2 activity, minimal beta activity

Q8. Which enzyme primarily metabolizes metaraminol?

• CYP3A4 in the liver
• Monoamine oxidase (MAO)
• Acetylcholinesterase
• Butyrylcholinesterase

Correct Answer: Monoamine oxidase (MAO)

Q9. Metaraminol is contraindicated or used with extreme caution in patients with:

• Hypotension due to spinal anaesthesia
• Pheochromocytoma
• Acute allergic reaction requiring epinephrine
• Type 1 diabetes without complications

Correct Answer: Pheochromocytoma

Q10. The most common acute adverse cardiovascular effects of metaraminol include:

• Bradycardia due to direct beta-1 agonism only
• Hypertension with reflex bradycardia and possible arrhythmias
• Marked vasodilation and syncope
• Prolonged QT interval only

Correct Answer: Hypertension with reflex bradycardia and possible arrhythmias

Q11. A dangerous drug interaction with metaraminol is seen when combined with:

• Monoamine oxidase inhibitors (MAOIs)
• Topical antihistamines
• Inhaled corticosteroids
• Oral iron supplements

Correct Answer: Monoamine oxidase inhibitors (MAOIs)

Q12. Regarding renal blood flow, metaraminol may:

• Consistently increase renal perfusion in all patients
• Reduce renal blood flow due to systemic vasoconstriction in some patients
• Have no vascular effects at all
• Cure chronic kidney disease

Correct Answer: Reduce renal blood flow due to systemic vasoconstriction in some patients

Q13. In obstetric practice metaraminol is:

• Never used due to proven teratogenicity
• Used cautiously and has been applied to treat maternal hypotension during spinal anaesthesia
• Recommended as first-line chronic antihypertensive in pregnancy
• Only administered orally to pregnant women

Correct Answer: Used cautiously and has been applied to treat maternal hypotension during spinal anaesthesia

Q14. A common adult IV bolus dosing range for metaraminol is approximately:

• 0.5–1 mg bolus, repeated as needed
• 50–100 mg bolus every hour
• Oral 10 mg once daily
• Topical 0.1% cream application

Correct Answer: 0.5–1 mg bolus, repeated as needed

Q15. Management of severe metaraminol-induced hypertension includes:

• Continue infusion and wait indefinitely
• Administration of an alpha‑adrenergic blocker such as phentolamine and supportive measures
• Give high-dose epinephrine
• Immediate dialysis

Correct Answer: Administration of an alpha‑adrenergic blocker such as phentolamine and supportive measures

Q16. Compared to a pure direct alpha agonist, an indirect component in a mixed-acting drug means:

• The drug only blocks neurotransmitter release
• The drug enhances release of endogenous norepinephrine in addition to direct receptor activation
• The drug only acts centrally and not peripherally
• The drug has no cardiovascular effects

Correct Answer: The drug enhances release of endogenous norepinephrine in addition to direct receptor activation

Q17. Which vasopressor is a pure direct alpha-1 agonist commonly compared to metaraminol?

• Epinephrine
• Norepinephrine
• Phenylephrine
• Dopamine

Correct Answer: Phenylephrine

Q18. Metaraminol intravenous infusion is commonly considered compatible with which IV fluid?

• 0.9% sodium chloride (normal saline)
• Strongly alkaline solutions such as concentrated bicarbonate
• Undiluted lipid emulsions only
• Commercial blood-derived products mixed directly

Correct Answer: 0.9% sodium chloride (normal saline)

Q19. What is the typical effect of metaraminol on heart rate immediately after a BP rise?

• Sustained tachycardia only
• Reflex bradycardia due to baroreceptor-mediated response
• No change in heart rate ever
• Cardiac arrest within seconds

Correct Answer: Reflex bradycardia due to baroreceptor-mediated response

Q20. Metaraminol is particularly useful in which type of shock when there is vasodilation due to loss of sympathetic tone?

• Cardiogenic shock due to pump failure only
• Neurogenic or spinal anaesthesia-induced hypotension
• Anaphylactic shock only (without airway management)
• Hypovolemic shock when fluids are contraindicated

Correct Answer: Neurogenic or spinal anaesthesia-induced hypotension

Q21. Pediatric dosing considerations for metaraminol commonly recommend:

• Fixed adult dose for all children
• Weight-based dosing, e.g., microgram per kg boluses (individualize and titrate)
• Oral dosing is preferred in emergencies
• Use only in neonates without adjustment

Correct Answer: Weight-based dosing, e.g., microgram per kg boluses (individualize and titrate)

Q22. Recommended storage for metaraminol injection includes:

• Storage frozen at -20°C
• Protection from light and storage at controlled room temperature per manufacturer
• Exposure to direct sunlight to maintain potency
• Long-term storage in opened multi-dose vials at room temperature for months

Correct Answer: Protection from light and storage at controlled room temperature per manufacturer

Q23. The duration of action of metaraminol is influenced most by which processes?

• Renal tubular secretion exclusively
• Reuptake into nerve terminals and metabolism by MAO
• Protein binding to albumin alone
• Gastric pH changes

Correct Answer: Reuptake into nerve terminals and metabolism by MAO

Q24. The indirect pressor effect of metaraminol occurs primarily by:

• Blocking vesicular monoamine transporter (VMAT)
• Displacing stored norepinephrine from synaptic vesicles into the synapse
• Stimulating nitric oxide synthase in endothelium
• Enhancing acetylcholine release at neuromuscular junctions

Correct Answer: Displacing stored norepinephrine from synaptic vesicles into the synapse

Q25. Metaraminol’s effect on pulmonary vascular resistance (PVR) is typically to:

• Decrease PVR markedly via beta-2 stimulation
• Increase or maintain PVR due to alpha-mediated vasoconstriction
• No effect on pulmonary vessels at all
• Cure pulmonary hypertension permanently

Correct Answer: Increase or maintain PVR due to alpha-mediated vasoconstriction

Q26. Which vasopressor is a pure direct alpha-1 agonist frequently chosen for rapid, short-term blood pressure support?

• Phenylephrine
• Metaraminol
• Isoproterenol
• Acetylcholine

Correct Answer: Phenylephrine

Q27. In patients taking nonselective beta-blockers, administration of metaraminol can cause:

• Complete elimination of pressor effect
• Exaggerated alpha-mediated hypertension and pronounced reflex bradycardia
• Unchanged hemodynamic response always
• Immediate bronchospasm due to beta-2 agonism

Correct Answer: Exaggerated alpha-mediated hypertension and pronounced reflex bradycardia

Q28. The oral bioavailability of metaraminol is generally:

• High due to excellent GI absorption
• Poor because of extensive first-pass metabolism by MAO
• 100% with no first-pass effect
• Irrelevant because it is a topical drug

Correct Answer: Poor because of extensive first-pass metabolism by MAO

Q29. The commercially available injectable salt commonly used clinically is:

• Metaraminol sulfate
• Metaraminol bitartrate
• Metaraminol hydrochloride only
• Metaraminol phosphate

Correct Answer: Metaraminol bitartrate

Q30. How does metaraminol primarily restore blood pressure after anaesthesia-induced hypotension?

• By vasodilation of splanchnic circulation only
• By systemic vasoconstriction (increased SVR) and venoconstriction to improve venous return
• By direct inotropic stimulation of myocardium as sole mechanism
• By blocking sympathetic outflow centrally

Correct Answer: By systemic vasoconstriction (increased SVR) and venoconstriction to improve venous return

Q31. Metaraminol is useful specifically for which anaesthesia-related complication?

• Persistent postoperative nausea unrelated to haemodynamics
• Hypotension due to spinal or epidural anesthesia
• Local anesthetic systemic toxicity reversal
• Prolonged neuromuscular blockade

Correct Answer: Hypotension due to spinal or epidural anesthesia

Q32. In patients with uncontrolled hypertension, metaraminol use carries what risk?

• It will normalize blood pressure without risk
• It may precipitate severe hypertensive episodes and end-organ damage
• It is the recommended chronic therapy
• It always produces hypotension instead

Correct Answer: It may precipitate severe hypertensive episodes and end-organ damage

Q33. When administering metaraminol IV, monitoring should routinely include:

• Only capillary blood glucose
• Continuous blood pressure, heart rate and ECG monitoring
• No monitoring is necessary for single bolus doses
• Only urine output hourly without vital sign checks

Correct Answer: Continuous blood pressure, heart rate and ECG monitoring

Q34. Is it advisable to mix metaraminol directly with blood products for transfusion?

• Yes, this is routine practice
• No, avoid direct mixing with blood products; use separate lines or compatible fluids
• Yes, but only if warmed to 42°C
• Only in pediatric blood transfusions

Correct Answer: No, avoid direct mixing with blood products; use separate lines or compatible fluids

Q35. Which vascular effect helps metaraminol increase venous return?

• Venodilation of splanchnic veins
• Venoconstriction increasing preload
• Capillary recruitment exclusively
• Direct renal vasodilation

Correct Answer: Venoconstriction increasing preload

Q36. Co-administration of tricyclic antidepressants (TCAs) with metaraminol can result in:

• Complete loss of metaraminol effect
• Enhanced pressor response and risk of severe hypertension
• Immediate hypoglycemia
• Antagonism of metaraminol causing hypotension

Correct Answer: Enhanced pressor response and risk of severe hypertension

Q37. In septic shock, compared with first-line agents like norepinephrine, metaraminol is:

• The preferred first-line agent in most guidelines
• Sometimes used as an alternative vasopressor when standard agents are unavailable or as a temporizing measure
• Contraindicated in all forms of septic shock
• Only used in oral form for septic shock

Correct Answer: Sometimes used as an alternative vasopressor when standard agents are unavailable or as a temporizing measure

Q38. Peripheral ischemia and tissue necrosis from extravasation are possible because metaraminol causes:

• Strong local vasodilation
• Alpha-mediated vasoconstriction at infusion/extravasation sites
• Direct enzymatic skin digestion
• Rapid bacterial contamination

Correct Answer: Alpha-mediated vasoconstriction at infusion/extravasation sites

Q39. What is a prudent maximum single bolus approach for metaraminol in routine practice?

• 50 mg bolus routinely
• Typically 0.5–1 mg bolus and titrate; avoid large unchecked boluses
• 10 g bolus for severe hypotension
• Oral 100 mg is the standard emergency dose

Correct Answer: Typically 0.5–1 mg bolus and titrate; avoid large unchecked boluses

Q40. The preferred pharmacologic antidote for severe alpha-mediated hypertension from metaraminol is:

• Propranolol
• Phentolamine (an alpha-adrenergic blocker)
• Atropine only
• Furosemide

Correct Answer: Phentolamine (an alpha-adrenergic blocker)

Q41. Does metaraminol readily cross the blood‑brain barrier?

• Yes, it has high CNS penetration producing central stimulation
• No, it has limited CNS penetration due to polarity and structure
• Yes, and it causes euphoria
• It permanently destroys the blood-brain barrier

Correct Answer: No, it has limited CNS penetration due to polarity and structure

Q42. Continuous infusion of metaraminol over time can lead to reduced response due to:

• Renal excretion saturation
• Peripheral tachyphylaxis from depletion of norepinephrine stores and receptor desensitization
• Enhanced potency over time with no tolerance
• Immediate allergic sensitization in all patients

Correct Answer: Peripheral tachyphylaxis from depletion of norepinephrine stores and receptor desensitization

Q43. Which metabolic pathway primarily terminates the action of the indirect component of metaraminol?

• Glucuronidation in the gut
• Monoamine oxidase (MAO) metabolism in nerve terminals and liver
• Renal filtration without metabolism
• Hydrolysis by plasma esterases

Correct Answer: Monoamine oxidase (MAO) metabolism in nerve terminals and liver

Q44. Structurally, metaraminol belongs to which chemical class?

• Sulfonylureas
• Sympathomimetic amines (phenethylamine/arylethanolamine derivatives)
• Benzodiazepines
• Beta-lactam antibiotics

Correct Answer: Sympathomimetic amines (phenethylamine/arylethanolamine derivatives)

Q45. Which of the following statements about commercial metaraminol preparation is correct?

• Metaraminol is only available as an oral sustained-release tablet
• It is commonly supplied as metaraminol bitartrate injection for parenteral use
• It is only available as an inhaled nebulizer solution
• It is available as an over-the-counter topical gel

Correct Answer: It is commonly supplied as metaraminol bitartrate injection for parenteral use

Q46. Use of metaraminol with MAO inhibitors may cause which severe reaction?

• Profound hypotension immediately
• Exaggerated and possibly life-threatening hypertension (hypertensive crisis)
• Complete loss of consciousness in all patients
• No interaction at all

Correct Answer: Exaggerated and possibly life-threatening hypertension (hypertensive crisis)

Q47. Reflex bradycardia after metaraminol administration occurs because:

• The drug directly stimulates the vagus nerve chemically
• Elevated arterial pressure activates baroreceptors, increasing vagal tone and decreasing heart rate
• The drug directly blocks sinoatrial node ion channels
• The drug chelates calcium in the bloodstream

Correct Answer: Elevated arterial pressure activates baroreceptors, increasing vagal tone and decreasing heart rate

Q48. For IV bolus administration, best practice regarding infusion site is:

• Use any small distal vein without monitoring
• Prefer central venous access or a large forearm vein for repeated boluses to reduce extravasation risk
• Always administer via intraosseous only
• Inject subcutaneously for fastest action

Correct Answer: Prefer central venous access or a large forearm vein for repeated boluses to reduce extravasation risk

Q49. Which intravenous solution should generally be avoided when preparing metaraminol for infusion?

• Normal saline (0.9% NaCl)
• Dextrose 5% in water (D5W)
• Strongly alkaline solutions such as concentrated sodium bicarbonate where compatibility is unknown
• Manufacturer‑recommended diluent per product label

Correct Answer: Strongly alkaline solutions such as concentrated sodium bicarbonate where compatibility is unknown

Q50. For B. Pharm students, the key learning point about metaraminol and mixed‑acting agents is to:

• Memorize a single dose for every clinical scenario without understanding mechanisms
• Understand receptor pharmacology, indirect vs direct actions, interactions (MAOIs/TCAs), dosing, monitoring and clinical implications
• Only focus on chemical synthesis and ignore clinical use
• Assume all vasopressors are interchangeable without risk

Correct Answer: Understand receptor pharmacology, indirect vs direct actions, interactions (MAOIs/TCAs), dosing, monitoring and clinical implications

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