Direct acting sympathomimetics – Epinephrine MCQs With Answer

Direct acting sympathomimetics – Epinephrine MCQs With Answer

by

Direct acting sympathomimetics – Epinephrine MCQs With Answer

Direct acting sympathomimetics like epinephrine (adrenaline) are cornerstone drugs in clinical pharmacology and emergency medicine. This keyword-rich introduction covers epinephrine’s mechanism at α and β adrenergic receptors, receptor selectivity, pharmacodynamic effects on cardiovascular, respiratory and metabolic systems, clinical uses (anaphylaxis, cardiac arrest, bronchodilation, vasopressor), dosing forms (1:1000, 1:10,000), metabolism (COMT, MAO), adverse effects and interactions relevant to B.Pharm students. These focused MCQs help you master receptor signaling, therapeutic rationale, contraindications, and safe dispensing practices. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which receptors are primarily activated by epinephrine at low therapeutic concentrations?

  • Predominantly α1 receptors
  • Predominantly β2 receptors
  • Predominantly β1 and β2 receptors
  • Only α2 receptors

Correct Answer: Predominantly β1 and β2 receptors

Q2. The primary mechanism by which epinephrine increases heart rate is:

  • Activation of cardiac muscarinic receptors
  • β1 receptor–mediated increase in cAMP in SA node
  • α1 mediated vasoconstriction increasing preload
  • Inhibition of ventricular Na+ channels

Correct Answer: β1 receptor–mediated increase in cAMP in SA node

Q3. Which enzyme is mainly responsible for the metabolic inactivation of epinephrine in the liver?

  • CYP3A4
  • Monoamine oxidase (MAO)
  • Catechol-O-methyltransferase (COMT)
  • Acetylcholinesterase

Correct Answer: Catechol-O-methyltransferase (COMT)

Q4. Epinephrine’s bronchodilator effect is predominantly mediated through:

  • α1 receptor stimulation
  • β2 receptor activation increasing cAMP in bronchial smooth muscle
  • Antagonism of histamine H1 receptors
  • Inhibition of phosphodiesterase type 5

Correct Answer: β2 receptor activation increasing cAMP in bronchial smooth muscle

Q5. The typical concentration of epinephrine used for intramuscular injection in anaphylaxis (EpiPen) is:

  • 1:1,000 (1 mg/mL)
  • 1:10,000 (0.1 mg/mL)
  • 1:100,000 (0.01 mg/mL)
  • 1:50,000 (0.02 mg/mL)

Correct Answer: 1:1,000 (1 mg/mL)

Q6. In cardiac arrest, epinephrine is administered intravenously typically at which concentration?

  • 1:1,000
  • 1:10,000
  • 1:100,000
  • Undiluted 1 mg/mL bolus

Correct Answer: 1:10,000

Q7. Which of the following adverse effects is most commonly associated with therapeutic doses of epinephrine?

  • Bradycardia
  • Tremor and palpitations
  • Hypoglycemia
  • Dry mouth due to anticholinergic action

Correct Answer: Tremor and palpitations

Q8. Epinephrine causes hyperglycemia by:

  • Stimulating pancreatic β cell insulin release
  • Increasing glycogenolysis via β2 receptors and inhibiting insulin via α2 receptors
  • Blocking glucagon secretion
  • Activating insulin receptors directly

Correct Answer: Increasing glycogenolysis via β2 receptors and inhibiting insulin via α2 receptors

Q9. Which statement about epinephrine and local anesthetics is correct?

  • Epinephrine decreases duration of local anesthesia by vasodilation
  • Epinephrine is contraindicated with local anesthetics because it inactivates them
  • Epinephrine prolongs local anesthetic action by vasoconstriction reducing systemic absorption
  • Epinephrine converts amide anesthetics to esters

Correct Answer: Epinephrine prolongs local anesthetic action by vasoconstriction reducing systemic absorption

Q10. Which receptor mediates the vasoconstrictive action of epinephrine on skin and mucosa?

  • β1 receptors
  • β2 receptors
  • α1 receptors
  • α2 receptors only

Correct Answer: α1 receptors

Q11. Compared to norepinephrine, epinephrine has relatively greater activity at which receptor?

  • α1 receptors only
  • β2 receptors
  • Dopaminergic receptors
  • Muscarinic receptors

Correct Answer: β2 receptors

Q12. Which of the following interactions increases the risk of severe hypertension when epinephrine is given?

  • Concurrent β-blocker therapy
  • Concurrent MAO inhibitor therapy
  • Concurrent ACE inhibitor therapy
  • Concurrent loop diuretic therapy

Correct Answer: Concurrent MAO inhibitor therapy

Q13. The term “direct-acting sympathomimetic” with respect to epinephrine means:

  • Epinephrine requires conversion to an active metabolite to act
  • Epinephrine directly binds and activates adrenergic receptors
  • Epinephrine causes catecholamine release from nerve terminals only
  • Epinephrine blocks adrenergic receptors

Correct Answer: Epinephrine directly binds and activates adrenergic receptors

Q14. Epinephrine’s effect on systolic and diastolic blood pressure at low doses is typically:

  • Increase in systolic, decrease in diastolic due to β2 vasodilation
  • Decrease in both systolic and diastolic
  • Increase in diastolic with no change in systolic
  • No effect on blood pressure

Correct Answer: Increase in systolic, decrease in diastolic due to β2 vasodilation

Q15. Which cellular second messenger system is activated by β-adrenergic receptors stimulated by epinephrine?

  • IP3/DAG via Gq
  • cAMP via Gs
  • cGMP via guanylyl cyclase
  • Direct ion channel opening without second messenger

Correct Answer: cAMP via Gs

Q16. Epinephrine administration can precipitate myocardial ischemia mainly due to:

  • Coronary vasodilation decreasing perfusion pressure
  • Increased myocardial oxygen demand from tachycardia and contractility
  • Reduction in afterload leading to decreased coronary perfusion
  • Activation of parasympathetic reflexes

Correct Answer: Increased myocardial oxygen demand from tachycardia and contractility

Q17. Which of the following is a contraindication or caution for epinephrine use?

  • Hypersensitivity to penicillin
  • Pheochromocytoma without α-blockade
  • Asthma refractory to β2 agonists
  • Bradycardia due to high vagal tone

Correct Answer: Pheochromocytoma without α-blockade

Q18. During anaphylaxis, epinephrine is life-saving because it:

  • Only blocks leukotriene receptors
  • Causes bronchoconstriction to limit allergens
  • Activates α1-mediated vasoconstriction and β2-mediated bronchodilation
  • Reduces IgE production immediately

Correct Answer: Activates α1-mediated vasoconstriction and β2-mediated bronchodilation

Q19. The phenomenon of tachyphylaxis to epinephrine refers to:

  • Enhanced response with repeated dosing
  • Rapid decrease in drug response after repeated administration
  • Permanent receptor upregulation
  • Delayed onset of action after multiple doses

Correct Answer: Rapid decrease in drug response after repeated administration

Q20. Which preparation of epinephrine is appropriate for topical hemostasis during minor surgery?

  • Epinephrine 1:10,000 IV bolus
  • Topical epinephrine-soaked gauze (concentrated solution)
  • Epinephrine subcutaneous 1:1,000 injection only
  • Oral epinephrine tablets

Correct Answer: Topical epinephrine-soaked gauze (concentrated solution)

Q21. Which structural feature is essential for epinephrine’s activity at adrenergic receptors?

  • A tertiary amine with long alkyl chain
  • Catechol ring with two hydroxyl groups at ortho positions
  • Large benzyl substituent at para position
  • Thioether linkage to aromatic ring

Correct Answer: Catechol ring with two hydroxyl groups at ortho positions

Q22. Epinephrine’s action to decrease renal blood flow is mainly mediated by:

  • β1-mediated renal vasodilation
  • α1-mediated renal vasoconstriction
  • Direct nephrotoxicity
  • Inhibition of renin release only

Correct Answer: α1-mediated renal vasoconstriction

Q23. A pharmacist should avoid mixing epinephrine with which IV solution due to instability?

  • Normal saline (0.9% NaCl)
  • Alkaline solutions such as sodium bicarbonate
  • Dextrose 5% in water (D5W)
  • Lactated Ringer’s solution

Correct Answer: Alkaline solutions such as sodium bicarbonate

Q24. Epinephrine’s effect on lipolysis is primarily through which receptor subtype?

  • α2 inhibitory receptors on adipocytes
  • β3 receptors increasing cAMP and activating hormone-sensitive lipase
  • Muscarinic receptors
  • Dopamine D2 receptors

Correct Answer: β3 receptors increasing cAMP and activating hormone-sensitive lipase

Q25. Which monitoring parameter is most important when administering IV epinephrine in an ICU?

  • Serum sodium concentration only
  • ECG and blood pressure monitoring
  • Urine ketones hourly
  • Pulse oximetry alone without BP

Correct Answer: ECG and blood pressure monitoring

Q26. The preferred route of epinephrine administration for severe anaphylaxis in the outpatient setting is:

  • IV bolus
  • Intramuscular injection into lateral thigh
  • Subcutaneous injection into abdomen
  • Inhalation via nebulizer

Correct Answer: Intramuscular injection into lateral thigh

Q27. Which of the following best explains “epinephrine reversal” when given after an α-blocker?

  • Epinephrine causes profound α-mediated vasoconstriction despite blockade
  • With α-blockade, β2 vasodilation predominates causing a fall in blood pressure
  • Epinephrine becomes inactivated by α-blockers leading to no effect
  • α-blockers convert epinephrine into norepinephrine

Correct Answer: With α-blockade, β2 vasodilation predominates causing a fall in blood pressure

Q28. Which laboratory change can epinephrine acutely cause?

  • Decrease in blood glucose
  • Increase in serum potassium due to β2 effect
  • Decrease in serum potassium (hypokalemia) due to β2-mediated cellular uptake
  • Increase in hemoglobin concentration by hemoconcentration only

Correct Answer: Decrease in serum potassium (hypokalemia) due to β2-mediated cellular uptake

Q29. Which statement about epinephrine’s pharmacokinetics is true?

  • Epinephrine has high oral bioavailability
  • Epinephrine is rapidly metabolized; short plasma half-life
  • Epinephrine is primarily excreted unchanged in urine
  • Epinephrine accumulates with chronic oral dosing

Correct Answer: Epinephrine is rapidly metabolized; short plasma half-life

Q30. In the context of local anesthesia with epinephrine, which concentration is commonly used to reduce systemic toxicity?

  • 1:50,000
  • 1:1,000
  • 1:100,000
  • 1:10

Correct Answer: 1:100,000

Q31. Which receptor subtype in vascular smooth muscle leads to contraction via IP3/Ca2+ pathway when stimulated by epinephrine?

  • β2 (Gs)
  • α1 (Gq)
  • β1 (Gi)
  • α2 (Gs)

Correct Answer: α1 (Gq)

Q32. Which clinical scenario most clearly indicates the use of intravenous epinephrine?

  • First-line treatment for mild allergic rhinitis
  • Cardiac arrest with asystole according to ACLS protocols
  • Chronic hypertension management
  • Long-term asthma controller therapy

Correct Answer: Cardiac arrest with asystole according to ACLS protocols

Q33. Combining epinephrine with a nonselective β-blocker may produce:

  • Pure β2-mediated vasodilation
  • Unopposed α-mediated hypertension and reflex bradycardia
  • Enhanced bronchodilation
  • Reduced half-life of epinephrine via increased metabolism

Correct Answer: Unopposed α-mediated hypertension and reflex bradycardia

Q34. Which change occurs in skeletal muscle blood flow with low-dose epinephrine?

  • Decrease due to α1 constriction
  • Increase due to β2-mediated vasodilation
  • No change because skeletal muscle lacks adrenergic receptors
  • Immediate thrombosis of capillaries

Correct Answer: Increase due to β2-mediated vasodilation

Q35. Epinephrine is stored in the adrenal medulla primarily in association with:

  • Lipid droplets
  • Chromaffin granules
  • Golgi vesicles
  • Mitochondria

Correct Answer: Chromaffin granules

Q36. Activation of presynaptic α2 receptors by catecholamines leads to:

  • Increased norepinephrine release
  • Decreased norepinephrine release (negative feedback)
  • Enhanced dopamine conversion to norepinephrine
  • Increased serotonin release

Correct Answer: Decreased norepinephrine release (negative feedback)

Q37. Which statement about epinephrine autoinjectors is correct?

  • Epinephrine autoinjectors deliver the IV dose used in ACLS
  • Autoinjectors are designed for intramuscular delivery into anterolateral thigh
  • They are intended for continuous infusion in outpatient settings
  • Autoinjectors should be injected into buttock for best absorption

Correct Answer: Autoinjectors are designed for intramuscular delivery into anterolateral thigh

Q38. Epinephrine-induced pulmonary edema in overdose results from:

  • Direct alveolar epithelial damage by catecholamines
  • Marked pulmonary vasoconstriction increasing hydrostatic pressure
  • Primary renal failure causing fluid overload only
  • Inhibition of surfactant synthesis

Correct Answer: Marked pulmonary vasoconstriction increasing hydrostatic pressure

Q39. Which agent would antagonize epinephrine’s bronchodilator effects most directly?

  • A selective β2 agonist
  • A β-blocker such as propranolol
  • An α1 agonist
  • An anticholinesterase

Correct Answer: A β-blocker such as propranolol

Q40. Which of the following best describes epinephrine’s effect on platelet function?

  • Strong direct inhibition of platelet aggregation via β2
  • Enhances platelet aggregation through α2-mediated platelet activation
  • No effect on platelets
  • Causes irreversible platelet depletion

Correct Answer: Enhances platelet aggregation through α2-mediated platelet activation

Q41. Which pediatric consideration is important when dosing epinephrine in anaphylaxis?

  • Children should always receive adult dose regardless of weight
  • IM dose is typically 0.01 mg/kg up to 0.3–0.5 mg per dose
  • IV dosing is preferred first-line in outpatient setting
  • Epinephrine is contraindicated in children under 12 years

Correct Answer: IM dose is typically 0.01 mg/kg up to 0.3–0.5 mg per dose

Q42. Which adverse endocrine effect can epinephrine provoke in susceptible patients?

  • Hypothyroidism
  • Thyroid storm due to increased catecholamine sensitivity in hyperthyroid patients
  • Primary adrenal insufficiency
  • Hyperprolactinemia

Correct Answer: Thyroid storm due to increased catecholamine sensitivity in hyperthyroid patients

Q43. What is the effect of epinephrine on renin release from the kidney?

  • It uniformly inhibits renin release via α1
  • β1 stimulation increases renin release
  • No effect on renin secretion
  • Directly converts angiotensinogen to angiotensin I

Correct Answer: β1 stimulation increases renin release

Q44. Which monitoring lab could be transiently altered after epinephrine administration in surgical settings?

  • Increase in blood glucose and lactic acid
  • Long-term increase in hemoglobin A1c immediately
  • Decrease in serum creatinine permanently
  • Increase in total cholesterol immediately

Correct Answer: Increase in blood glucose and lactic acid

Q45. Epinephrine’s effect on uterine smooth muscle is mainly via:

  • α1-mediated relaxation
  • β2-mediated relaxation (tocolysis)
  • Cholinergic receptor antagonism causing contraction
  • Direct mechanical stimulation only

Correct Answer: β2-mediated relaxation (tocolysis)

Q46. Which of the following best characterizes epinephrine’s stereochemistry relevant to activity?

  • Both enantiomers are equally active at adrenergic receptors
  • L-(−)-epinephrine (natural isomer) is more active at adrenergic receptors
  • Only the D-(+)-enantiomer is active
  • Stereochemistry is irrelevant for receptor binding

Correct Answer: L-(−)-epinephrine (natural isomer) is more active at adrenergic receptors

Q47. In the preservation and storage of epinephrine vials, which practice is recommended?

  • Store exposed to light to prevent precipitation
  • Store in a cool, dark place and avoid prolonged exposure to light and heat
  • Freeze vials to extend shelf life
  • Store in alkaline solution to stabilize catechol group

Correct Answer: Store in a cool, dark place and avoid prolonged exposure to light and heat

Q48. Which of the following explains why epinephrine has poor oral bioavailability?

  • Extensive first-pass metabolism by MAO and COMT and poor stability in GI tract
  • Rapid absorption and complete first-pass activation to more potent metabolites
  • It is too lipophilic to cross GI epithelium
  • It binds strongly to intestinal mucin preventing absorption

Correct Answer: Extensive first-pass metabolism by MAO and COMT and poor stability in GI tract

Q49. Which statement about epinephrine-induced glycogenolysis is correct?

  • Glycogenolysis occurs primarily in adipose tissue via epinephrine
  • Epinephrine stimulates hepatic glycogenolysis via β2 receptors increasing blood glucose
  • Epinephrine inhibits glycogen phosphorylase reducing glucose output
  • Glycogenolysis is independent of receptor activation

Correct Answer: Epinephrine stimulates hepatic glycogenolysis via β2 receptors increasing blood glucose

Q50. Which pharmacological principle explains why epinephrine’s cardiovascular effects vary with dose?

  • Dose-dependent receptor selectivity and differential activation of α and β receptors
  • Epinephrine binds only a single receptor regardless of dose
  • Pharmacokinetics remain constant so effects do not change with dose
  • Receptor number increases proportionally with dose

Correct Answer: Dose-dependent receptor selectivity and differential activation of α and β receptors

Leave a Comment