Direct acting sympathomimetics – Dobutamine MCQs With Answer

Direct acting sympathomimetics – Dobutamine MCQs With Answer

Dobutamine is a prototypical direct acting sympathomimetic and beta1-selective inotropic agent widely studied in cardiovascular pharmacology. This concise, SEO-friendly introduction covers key concepts for B. Pharm students: mechanism of action as a beta1 agonist, hemodynamic effects, indications in acute heart failure and cardiogenic shock, pharmacokinetics, dosing and IV administration, adverse effects like tachyarrhythmia and ischemia, receptor selectivity versus dopamine and isoproterenol, and important drug interactions. These focused MCQs emphasize clinical pharmacology, receptor pharmacodynamics, metabolism, monitoring, and contraindications to build exam-ready understanding. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary receptor target of dobutamine responsible for its positive inotropic effect?

• Alpha-1 adrenergic receptor
• Beta-2 adrenergic receptor
• Beta-1 adrenergic receptor
• Muscarinic M2 receptor

Correct Answer: Beta-1 adrenergic receptor

Q2. Dobutamine is classified as which type of sympathomimetic based on action?

• Indirect acting sympathomimetic
• Mixed acting sympathomimetic
• Direct acting sympathomimetic
• Cholinergic agonist

Correct Answer: Direct acting sympathomimetic

Q3. Which hemodynamic change is most characteristic after IV dobutamine infusion?

• Decrease in cardiac output
• Increase in cardiac output
• Marked systemic vasoconstriction
• Significant decrease in heart rate

Correct Answer: Increase in cardiac output

Q4. Dobutamine has relatively selective activity at which adrenergic receptor subtype?

• Beta-1 over beta-2 and alpha-1
• Beta-2 over beta-1 and alpha-1
• Alpha-1 over beta receptors
• Equal affinity for muscarinic receptors

Correct Answer: Beta-1 over beta-2 and alpha-1

Q5. The main clinical indication for dobutamine is:

• Bronchial asthma maintenance therapy
• Acute decompensated heart failure and cardiogenic shock
• Chronic hypertension control
• Diuretic-resistant edema

Correct Answer: Acute decompensated heart failure and cardiogenic shock

Q6. Which adverse effect is commonly associated with dobutamine infusion?

• Bradycardia
• Tachyarrhythmias
• Excessive salivation
• Severe hyperkalemia

Correct Answer: Tachyarrhythmias

Q7. Dobutamine exhibits what effect on systemic vascular resistance (SVR) at typical doses?

• Marked increase in SVR
• No change in SVR
• Variable; often slight decrease in SVR
• Profound vasodilation causing hypotension

Correct Answer: Variable; often slight decrease in SVR

Q8. The onset of action after IV bolus of dobutamine occurs within:

• 24–48 hours
• 15–30 minutes
• 1–2 hours
• Minutes (1–2 minutes)

Correct Answer: Minutes (1–2 minutes)

Q9. Which metabolic pathway predominantly metabolizes dobutamine?

• CYP3A4 hepatic oxidation
• MAO and COMT enzymatic metabolism
• Renal glucuronidation
• Hydrolysis by plasma esterases

Correct Answer: MAO and COMT enzymatic metabolism

Q10. Dobutamine’s inotropic action increases myocardial oxygen consumption primarily because it:

• Reduces cardiac contractility
• Decreases heart rate markedly
• Enhances contractility and heart rate
• Improves coronary vasodilation without changing contractility

Correct Answer: Enhances contractility and heart rate

Q11. Which monitoring parameter is most important during dobutamine infusion?

• Serum potassium only
• Pulse, blood pressure and ECG monitoring
• Fasting blood glucose hourly
• Daily complete blood count

Correct Answer: Pulse, blood pressure and ECG monitoring

Q12. Compared to dopamine, dobutamine is preferred for increasing:

• Renal perfusion preferentially
• Contractility with less tachycardia
• Peripheral vasoconstriction
• Alpha-1 mediated vasoconstriction

Correct Answer: Contractility with less tachycardia

Q13. Which dosage form is dobutamine commonly available as for clinical use?

• Oral tablets
• Subcutaneous depot injection
• Intravenous infusion solution
• Transdermal patch

Correct Answer: Intravenous infusion solution

Q14. Dobutamine is contraindicated in patients with:

• Hypersensitivity to beta blockers
• Tachyarrhythmias that compromise cardiac output
• Well-controlled asthma
• Anemia

Correct Answer: Tachyarrhythmias that compromise cardiac output

Q15. The half-life of dobutamine is approximately:

• 10–12 hours
• 2–3 minutes
• 2 minutes
• 1 week

Correct Answer: 2 minutes

Q16. In heart failure, dobutamine primarily improves stroke volume by:

• Increasing venous return only
• Enhancing myocardial contractility via beta-1 stimulation
• Blocking calcium channels
• Antagonizing aldosterone receptors

Correct Answer: Enhancing myocardial contractility via beta-1 stimulation

Q17. A known pharmacodynamic effect of dobutamine on pulmonary circulation is:

• Marked pulmonary vasoconstriction worsening pulmonary edema
• Reduced pulmonary vascular resistance secondary to increased output
• Direct bronchoconstriction
• Complete blockade of pulmonary reflexes

Correct Answer: Reduced pulmonary vascular resistance secondary to increased output

Q18. Which ECG change may occur during dobutamine infusion?

• QT prolongation exclusively
• ST segment changes and arrhythmias
• No ECG changes ever observed
• Consistent PR interval prolongation only

Correct Answer: ST segment changes and arrhythmias

Q19. Tolerance to dobutamine can develop due to:

• Receptor upregulation
• Receptor desensitization and downregulation
• Increased drug absorption in GI tract
• Prolonged renal clearance

Correct Answer: Receptor desensitization and downregulation

Q20. Which drug interaction is clinically significant with dobutamine?

• Combined use with beta blockers reduces dobutamine effect
• Use with diuretics leads to increased dobutamine potency
• Concurrent digoxin inactivates dobutamine chemically
• ACE inhibitors cause immediate hypersensitivity to dobutamine

Correct Answer: Combined use with beta blockers reduces dobutamine effect

Q21. Dobutamine’s stereochemistry contributes to its pharmacology because:

• Only one enantiomer is active and others are inert
• Different enantiomers have opposing alpha and beta activities
• Stereochemistry is irrelevant to receptor binding
• It exists only as a racemic non-chiral molecule

Correct Answer: Different enantiomers have opposing alpha and beta activities

Q22. Which laboratory value should be closely watched during prolonged dobutamine therapy?

• Liver enzymes weekly only
• Serum lactate and electrolytes, especially potassium
• Fasting lipid profile
• Hemoglobin A1c monthly

Correct Answer: Serum lactate and electrolytes, especially potassium

Q23. Inotropic support with dobutamine is most effective in which type of shock?

• Hypovolemic shock without fluid resuscitation
• Cardiogenic shock with low cardiac output
• Anaphylactic shock as first-line therapy
• Obstructive shock due to mechanical obstruction

Correct Answer: Cardiogenic shock with low cardiac output

Q24. Which statement about dobutamine and coronary perfusion is correct?

• Dobutamine always reduces coronary blood flow
• Increased cardiac output can improve coronary perfusion despite higher oxygen demand
• It directly causes coronary artery spasm in all patients
• Dobutamine selectively dilates coronary arteries without affecting heart rate

Correct Answer: Increased cardiac output can improve coronary perfusion despite higher oxygen demand

Q25. The use of dobutamine stress echocardiography relies on:

• Its ability to lower myocardial contractility for testing
• Provocation of regional wall motion abnormalities via increased contractility
• Direct contrast imaging properties of the drug
• Long-term remodeling effects

Correct Answer: Provocation of regional wall motion abnormalities via increased contractility

Q26. Which patient population requires careful consideration before dobutamine use due to increased sensitivity?

• Young healthy athletes
• Pediatric and elderly patients with limited cardiac reserve
• Patients on topical antibiotics
• Patients with hyperthyroidism only

Correct Answer: Pediatric and elderly patients with limited cardiac reserve

Q27. The primary route of elimination for dobutamine metabolites is:

• Renal excretion
• Biliary secretion into feces exclusively
• Exhalation via lungs
• Storage in adipose tissue

Correct Answer: Renal excretion

Q28. Which pharmacodynamic property distinguishes dobutamine from norepinephrine?

• Dobutamine has stronger alpha-1 vasoconstrictive effects
• Dobutamine is more beta-1 selective and less vasoconstrictive
• Norepinephrine is primarily a beta-2 agonist
• They are pharmacodynamically identical

Correct Answer: Dobutamine is more beta-1 selective and less vasoconstrictive

Q29. During dobutamine infusion, myocardial ischemia risk increases predominantly because:

• It directly forms coronary thrombi
• Increased myocardial oxygen demand may outstrip supply
• It causes acute severe anemia
• It blocks adenosine receptors in coronary vessels

Correct Answer: Increased myocardial oxygen demand may outstrip supply

Q30. Which clinical parameter indicates improved response to dobutamine in acute heart failure?

• Rising central venous pressure with worsening urine output
• Increased urine output, improved blood pressure and perfusion
• Progressive lactate elevation
• Worsening pulmonary edema on chest X-ray

Correct Answer: Increased urine output, improved blood pressure and perfusion

Q31. Which statement about dobutamine dosing is correct?

• It is dosed orally once daily
• Infusion rates are titrated based on hemodynamic response, commonly 2.5–20 mcg/kg/min
• Fixed high-dose boluses are standard practice
• Topical dosing is recommended for heart failure

Correct Answer: Infusion rates are titrated based on hemodynamic response, commonly 2.5–20 mcg/kg/min

Q32. Which physiological reflex may attenuate the heart rate response to dobutamine?

• Baroreceptor-mediated reflex bradycardia due to increased blood pressure
• Increased sympathetic outflow causing paradoxical bradycardia
• Direct inhibition of sinoatrial node by dobutamine
• Peripheral chemoreceptor suppression leading to tachycardia

Correct Answer: Baroreceptor-mediated reflex bradycardia due to increased blood pressure

Q33. In patients receiving MAO inhibitors, dobutamine effects may be:

• Reduced due to competitive metabolism
• Unchanged
• Potentiated because MAO inhibition slows metabolism of catecholamines
• Converted into a steroid-like compound

Correct Answer: Potentiated because MAO inhibition slows metabolism of catecholamines

Q34. Which adverse effect necessitates immediate reduction or discontinuation of dobutamine?

• Mild headache
• Development of ventricular arrhythmias
• Minor orthostatic dizziness
• Mild cough

Correct Answer: Development of ventricular arrhythmias

Q35. How does dobutamine affect systolic and diastolic function acutely?

• Only improves diastolic relaxation, not systolic function
• Improves systolic contractility and may enhance diastolic relaxation
• Worsens both systolic and diastolic function
• Has no cardiac effects

Correct Answer: Improves systolic contractility and may enhance diastolic relaxation

Q36. Which statement about dobutamine in pregnancy is correct?

• It is absolutely contraindicated in all trimesters
• It may be used when maternal hemodynamic stabilization is necessary, with caution
• It is recommended as first-line to treat chronic hypertension in pregnancy
• It has proven teratogenic effects and is banned

Correct Answer: It may be used when maternal hemodynamic stabilization is necessary, with caution

Q37. Which monitoring device is most useful to assess immediate dobutamine effect on cardiac output?

• 24-hour Holter monitor only
• Continuous invasive arterial pressure and echocardiography or thermodilution cardiac output monitoring
• Fasting lipid panel
• Pulmonary function tests

Correct Answer: Continuous invasive arterial pressure and echocardiography or thermodilution cardiac output monitoring

Q38. Which is a pharmacologic reason dobutamine may be preferred over milrinone in some patients?

• Dobutamine is a phosphodiesterase inhibitor like milrinone
• Dobutamine primarily acts via beta-1 receptors and has shorter half-life allowing rapid titration
• Dobutamine causes long-lasting vasodilation ideal for outpatient use
• Milrinone lacks inotropic effects

Correct Answer: Dobutamine primarily acts via beta-1 receptors and has shorter half-life allowing rapid titration

Q39. Which laboratory sign may indicate myocardial ischemia during dobutamine therapy?

• Decreased troponin levels
• Rising cardiac troponin and CK-MB
• Low serum creatinine only
• Elevated hemoglobin without symptoms

Correct Answer: Rising cardiac troponin and CK-MB

Q40. Which combination is potentially hazardous and requires caution when using dobutamine?

• Dobutamine with beta blockers to enhance effect
• Dobutamine with monoamine oxidase inhibitors due to potentiation
• Dobutamine with isotonic saline infusion only
• Dobutamine with aspirin for cardioprotection

Correct Answer: Dobutamine with monoamine oxidase inhibitors due to potentiation

Q41. Inotropic effect of dobutamine is mediated by increased intracellular:

• Sodium via Na/K ATPase inhibition only
• Cyclic AMP leading to enhanced calcium entry
• cGMP causing vasodilation without contractile change
• ATP depletion in myocytes

Correct Answer: Cyclic AMP leading to enhanced calcium entry

Q42. Dobutamine may be less effective in patients with chronic beta-blocker therapy because:

• Beta blockers upregulate beta receptors making dobutamine too potent
• Beta blockers competitively inhibit beta-1 receptors, reducing dobutamine action
• Beta blockers increase renal clearance of dobutamine
• There is no interaction between them

Correct Answer: Beta blockers competitively inhibit beta-1 receptors, reducing dobutamine action

Q43. Which pharmacokinetic property explains dobutamine’s rapid titratability?

• High oral bioavailability
• Very short plasma half-life and rapid metabolism
• Depot formation at injection site
• Slow hepatic clearance over days

Correct Answer: Very short plasma half-life and rapid metabolism

Q44. A careful consideration when using dobutamine in ischemic heart disease is to:

• Use the highest possible dose immediately
• Balance inotropic benefit against increased oxygen demand and monitor closely
• Avoid ECG monitoring since it adds no value
• Stop all anti-anginal therapy

Correct Answer: Balance inotropic benefit against increased oxygen demand and monitor closely

Q45. Which receptor action at high doses of dobutamine may contribute to vasoconstriction?

• Activation of muscarinic receptors
• Alpha-1 adrenergic receptor stimulation from certain stereoisomers
• Direct nitric oxide release
• Blockade of alpha-2 receptors only

Correct Answer: Alpha-1 adrenergic receptor stimulation from certain stereoisomers

Q46. For B. Pharm students, understanding dobutamine’s mechanism best supports learning in which subject area?

• Pharmaceutical analysis only
• Clinical pharmacology and therapeutics
• Pharmaceutical chemistry of ointments
• Biostatistics exclusively

Correct Answer: Clinical pharmacology and therapeutics

Q47. Which feature makes dobutamine suitable for short-term cardiac support?

• Long duration of action with once-weekly dosing
• Rapid onset and short half-life allowing quick titration and withdrawal
• Oral administration for home use
• Ineffectiveness at clinical doses

Correct Answer: Rapid onset and short half-life allowing quick titration and withdrawal

Q48. Which sign suggests inadequate response to dobutamine in cardiogenic shock?

• Improved mentation and urine output
• Persistent hypotension and rising lactate despite titration
• Decreased heart rate and improved perfusion
• Resolution of pulmonary congestion

Correct Answer: Persistent hypotension and rising lactate despite titration

Q49. In pharmacology exams, dobutamine’s classification is most commonly taught under:

• Calcium channel blockers
• Direct-acting catecholamine beta-adrenergic agonists
• ACE inhibitors
• Loop diuretics

Correct Answer: Direct-acting catecholamine beta-adrenergic agonists

Q50. A key counseling point for health professionals managing dobutamine therapy is to:

• Advise patients to take dobutamine with meals at home
• Ensure continuous IV infusion under monitoring and adjust dose based on hemodynamic response
• Recommend long-term outpatient use without monitoring
• Suggest combining with OTC stimulants to improve effect

Correct Answer: Ensure continuous IV infusion under monitoring and adjust dose based on hemodynamic response

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com