Direct acting sympathomimetics – Salbutamol MCQs With Answer

Direct acting sympathomimetics – Salbutamol MCQs With Answer is a focused study resource for B.Pharm students covering the pharmacology, clinical use, and safety of salbutamol (albuterol). This introduction emphasizes beta-2 agonist mechanism, receptor selectivity, inhalation delivery, pharmacokinetics, adverse effects, drug interactions, dosing and monitoring in respiratory disorders. Questions are designed to deepen understanding of molecular pharmacology, therapeutic indications, administration techniques and emergency management of bronchospasm. Ideal for exam prep and revision, these MCQs reinforce rational prescribing and patient counseling skills while integrating up-to-date concepts in bronchodilator therapy. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary receptor target of salbutamol?

• Alpha-1 adrenergic receptor
• Beta-1 adrenergic receptor
• Beta-2 adrenergic receptor
• Muscarinic M3 receptor

Correct Answer: Beta-2 adrenergic receptor

Q2. Which of the following best describes salbutamol’s mechanism of action?

• Inhibition of acetylcholinesterase
• Direct activation of adenylate cyclase via beta-2 receptors increasing cAMP
• Blocking calcium channels in smooth muscle
• Antagonism of histamine H1 receptors

Correct Answer: Direct activation of adenylate cyclase via beta-2 receptors increasing cAMP

Q3. Salbutamol is commonly used clinically as a:

• Long-acting oral antihypertensive
• Short-acting bronchodilator for acute bronchospasm
• Proton pump inhibitor
• Central nervous system stimulant

Correct Answer: Short-acting bronchodilator for acute bronchospasm

Q4. The onset of action for inhaled salbutamol is typically:

• 1–5 minutes
• 30–60 minutes
• 2–4 hours
• 24 hours

Correct Answer: 1–5 minutes

Q5. Which formulation of salbutamol is preferred for acute severe bronchospasm in adults?

• Oral sustained-release tablets
• Subcutaneous injection
• Inhaled metered-dose inhaler or nebulized solution
• Topical cream

Correct Answer: Inhaled metered-dose inhaler or nebulized solution

Q6. A common systemic adverse effect of excessive salbutamol use is:

• Bradycardia
• Hypoglycemia
• Tremor
• Constipation

Correct Answer: Tremor

Q7. Which statement about receptor selectivity of salbutamol is correct?

• It is highly selective for beta-1 receptors over beta-2
• It is a non-selective adrenergic agonist acting equally on alpha and beta receptors
• It preferentially stimulates beta-2 receptors with some beta-1 activity at high doses
• It selectively blocks beta-2 receptors

Correct Answer: It preferentially stimulates beta-2 receptors with some beta-1 activity at high doses

Q8. The major metabolic pathway for salbutamol is:

• Hepatic oxidative deamination by MAO
• Sulfation and glucuronidation primarily in the liver
• Methylation by catechol-O-methyltransferase (COMT)
• Direct renal excretion unchanged only

Correct Answer: Sulfation and glucuronidation primarily in the liver

Q9. Which pharmacokinetic property is true for inhaled salbutamol?

• High bioavailability after oral administration producing rapid effect
• Significant first-pass metabolism reduces oral bioavailability
• Completely metabolized in the lungs with no systemic absorption
• Eliminated primarily by pulmonary exhalation

Correct Answer: Significant first-pass metabolism reduces oral bioavailability

Q10. Which ECG change may be seen with salbutamol overdose?

• Prolonged PR interval only
• ST-segment elevation in all leads
• Tachycardia and possible hypokalemia-related U waves
• Complete heart block

Correct Answer: Tachycardia and possible hypokalemia-related U waves

Q11. How does salbutamol cause hypokalemia?

• By increasing renal potassium excretion directly
• By shifting potassium into cells via stimulation of Na+/K+-ATPase through beta-2 activation
• By binding potassium in the gut
• By blocking potassium absorption in the intestines

Correct Answer: By shifting potassium into cells via stimulation of Na+/K+-ATPase through beta-2 activation

Q12. Which patient group requires caution when prescribing salbutamol due to potential cardiac effects?

• Patients with well-controlled asthma and no comorbidities
• Patients with ischemic heart disease or arrhythmias
• Young healthy athletes
• Patients with chronic kidney disease only

Correct Answer: Patients with ischemic heart disease or arrhythmias

Q13. The recommended reliever dose for salbutamol via metered-dose inhaler (MDI) in adults is usually:

• 1 puff every 12 hours
• 1–2 puffs every 4–6 hours as needed for bronchospasm
• 10 puffs every hour continuously
• One puff only once in lifetime

Correct Answer: 1–2 puffs every 4–6 hours as needed for bronchospasm

Q14. Which of the following is a long-acting beta-2 agonist used for maintenance rather than salbutamol?

• Terbutaline
• Salmeterol
• Ephedrine
• Phenylephrine

Correct Answer: Salmeterol

Q15. Nebulized salbutamol is preferred over MDI in which situation?

• Mild intermittent asthma controlled with a spacer
• Severe acute asthma or when the patient cannot coordinate inhaler use
• For routine long-term control therapy
• For treating allergic rhinitis only

Correct Answer: Severe acute asthma or when the patient cannot coordinate inhaler use

Q16. Which drug interaction increases the risk of tachyarrhythmia with salbutamol?

• Concurrent use of inhaled corticosteroids
• Non-selective beta-blockers like propranolol
• Concurrent systemic corticosteroids
• Monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants

Correct Answer: Monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants

Q17. Which monitoring parameter is important during high-dose salbutamol therapy?

• Serum sodium only
• Blood glucose and serum potassium
• Platelet count weekly
• Urine culture periodically

Correct Answer: Blood glucose and serum potassium

Q18. Which stereochemical property is relevant to salbutamol?

• It is a racemic mixture with (R)-enantiomer primarily responsible for beta-2 activity
• It exists only as a single achiral molecule
• Its (S)-enantiomer is the active bronchodilator
• Chirality does not affect its pharmacology

Correct Answer: It is a racemic mixture with (R)-enantiomer primarily responsible for beta-2 activity

Q19. Tolerance to salbutamol with frequent use is mainly due to:

• Upregulation of beta-2 receptors
• Downregulation/desensitization of beta-2 receptors
• Increased muscarinic receptor activity
• Depletion of synaptic norepinephrine

Correct Answer: Downregulation/desensitization of beta-2 receptors

Q20. In pregnancy, salbutamol is classified as which category (general guidance)?

• Contraindicated in all trimesters
• Generally considered safe when clinically indicated with caution
• Teratogenic and banned
• Safe without any monitoring

Correct Answer: Generally considered safe when clinically indicated with caution

Q21. The use of salbutamol can lead to which metabolic disturbance during therapy?

• Hypercalcemia
• Hypokalemia
• Hyponatremia only
• Metabolic acidosis

Correct Answer: Hypokalemia

Q22. Which of these is NOT a clinical indication for salbutamol?

• Acute exacerbation of asthma
• Bronchospasm due to COPD
• Hyperthyroidism as first-line therapy
• Prevention of exercise-induced bronchoconstriction

Correct Answer: Hyperthyroidism as first-line therapy

Q23. The primary route of elimination for salbutamol and its metabolites is:

• Fecal excretion only
• Renal excretion via urine
• Exhaled air as unchanged drug
• Biliary secretion solely

Correct Answer: Renal excretion via urine

Q24. What counseling point should be given to patients using an MDI for salbutamol?

• Shake the inhaler, exhale fully, actuate while inhaling deeply, and hold breath for ~10 seconds
• Use the inhaler while exhaling slowly for two minutes
• Always swallow the inhaled dose to increase absorption
• Store the inhaler in the freezer at all times

Correct Answer: Shake the inhaler, exhale fully, actuate while inhaling deeply, and hold breath for ~10 seconds

Q25. Which is a sign of salbutamol overdose requiring urgent attention?

• Mild dry mouth
• Severe tachycardia, seizures, significant hypotension
• Improved breath sounds
• Slight improvement in exercise tolerance

Correct Answer: Severe tachycardia, seizures, significant hypotension

Q26. Which of the following drugs may antagonize the bronchodilator effect of salbutamol?

• Albuterol (same drug)
• Propranolol, a non-selective beta-blocker
• Salmeterol, a long-acting beta-2 agonist
• Theophylline at therapeutic levels

Correct Answer: Propranolol, a non-selective beta-blocker

Q27. In pediatric dosing, inhaled salbutamol via MDI with spacer is preferred because:

• Children cannot develop side effects from inhaled drugs
• It improves drug delivery to lungs and reduces oropharyngeal deposition
• It makes the drug systemic faster
• It eliminates the need for monitoring vital signs

Correct Answer: It improves drug delivery to lungs and reduces oropharyngeal deposition

Q28. A clinical benefit of adding a spacer to an MDI is:

• Reduced lung deposition and increased throat side effects
• Improved coordination, increased lung deposition, and reduced oropharyngeal deposition
• It chemically alters salbutamol making it longer acting
• It converts salbutamol into an oral medication

Correct Answer: Improved coordination, increased lung deposition, and reduced oropharyngeal deposition

Q29. Which physiologic effect in skeletal muscle is associated with beta-2 agonists like salbutamol?

• Muscle paralysis
• Increased glycogenolysis and tremor
• Decreased blood flow to muscles
• Permanent muscle hypertrophy

Correct Answer: Increased glycogenolysis and tremor

Q30. Which laboratory change may be observed after high-dose salbutamol therapy?

• Hyperkalemia due to muscle breakdown
• Elevated serum potassium due to cell lysis
• Decreased serum potassium due to intracellular shift
• Marked leukopenia

Correct Answer: Decreased serum potassium due to intracellular shift

Q31. Salbutamol’s clinical effect on bronchial smooth muscle is mediated by which intracellular messenger?

• cGMP
• cAMP
• Inositol triphosphate (IP3)
• Diacylglycerol (DAG)

Correct Answer: cAMP

Q32. Which adverse reaction is more common with systemic (oral) salbutamol compared to inhaled therapy?

• Localized throat irritation only
• Increased systemic side effects like tremor, tachycardia and hypokalemia
• Improved local bronchodilation without side effects
• Increased risk of topical dermatitis

Correct Answer: Increased systemic side effects like tremor, tachycardia and hypokalemia

Q33. The use of salbutamol as a tocolytic (to suppress preterm labor) is characterized by:

• First-line, safe long-term use without monitoring
• Occasional off-label short-term use with cardiovascular risks
• Primary uterine stimulant action
• It is ineffective on uterine smooth muscle

Correct Answer: Occasional off-label short-term use with cardiovascular risks

Q34. Which of the following best explains why salbutamol can produce hyperglycemia?

• By decreasing hepatic gluconeogenesis
• By stimulating glycogenolysis and increasing hepatic glucose output via beta-2 activation
• By directly increasing insulin secretion
• By inhibiting pancreatic alpha cells

Correct Answer: By stimulating glycogenolysis and increasing hepatic glucose output via beta-2 activation

Q35. When switching a patient from nebulized salbutamol to MDI, what is an important consideration?

• MDI delivers significantly higher systemic dose always
• Use of a spacer and correct inhaler technique to ensure equivalent lung delivery
• MDI cannot be used in adults
• No dose adjustment or instruction is required

Correct Answer: Use of a spacer and correct inhaler technique to ensure equivalent lung delivery

Q36. Which is an appropriate first-line action for a patient experiencing an acute asthma attack?

• Administer inhaled salbutamol immediately
• Prescribe long-term leukotriene modifiers only
• Administer oral antibiotics
• Delay treatment until symptoms worsen

Correct Answer: Administer inhaled salbutamol immediately

Q37. Which of the following statements about salbutamol and exercise-induced bronchoconstriction (EIB) is correct?

• Salbutamol is ineffective for EIB
• Inhaled salbutamol 15–30 minutes before exercise can prevent EIB
• Oral salbutamol must be taken daily to prevent EIB only
• Salbutamol should be taken immediately after exercise to prevent EIB

Correct Answer: Inhaled salbutamol 15–30 minutes before exercise can prevent EIB

Q38. Which pharmacodynamic interaction could potentiate hypokalemia when combined with salbutamol?

• Concurrent treatment with potassium-sparing diuretics
• Concurrent use of high-dose insulin
• Concurrent use of loop diuretics like furosemide
• Concurrent alkali therapy only

Correct Answer: Concurrent use of loop diuretics like furosemide

Q39. Which adverse effect is LESS likely with low-dose inhaled salbutamol?

• Palpitations and nervousness
• Oral thrush
• Tremor
• Headache

Correct Answer: Oral thrush

Q40. What is the role of salbutamol in COPD management?

• It is only used for infection treatment in COPD
• Short-acting salbutamol provides symptom relief for bronchospasm but long-acting bronchodilators are preferred for maintenance
• It cures COPD permanently
• It is contraindicated in COPD

Correct Answer: Short-acting salbutamol provides symptom relief for bronchospasm but long-acting bronchodilators are preferred for maintenance

Q41. Which sign indicates inadequate inhaler technique when using an MDI for salbutamol?

• Immediate symptomatic relief and improved peak flow
• Oral candidiasis development only
• Wheezing persists and poor coordination with actuation and inhalation
• Proper spacer use

Correct Answer: Wheezing persists and poor coordination with actuation and inhalation

Q42. In severe asthma unresponsive to initial salbutamol, which therapy might be added in the emergency setting?

• Intravenous magnesium sulfate and systemic corticosteroids
• Oral metformin
• Topical antihistamine cream
• Subcutaneous epinephrine exclusively for all cases

Correct Answer: Intravenous magnesium sulfate and systemic corticosteroids

Q43. Pharmacologically, why are inhaled beta-2 agonists preferred over oral forms for acute relief?

• Inhaled route produces slower onset but less effect
• Inhaled route provides rapid local effect with lower systemic exposure and fewer side effects
• Oral forms are completely inactive
• Inhaled route is more expensive and thus better

Correct Answer: Inhaled route provides rapid local effect with lower systemic exposure and fewer side effects

Q44. Which structural feature of salbutamol contributes to beta-2 selectivity?

• Large lipophilic aromatic ring only
• Substitution on the amine side chain and steric features favoring beta-2 interaction
• It has no functional groups related to receptor selectivity
• Its sulfate group confers selectivity

Correct Answer: Substitution on the amine side chain and steric features favoring beta-2 interaction

Q45. Which clinical test can assess bronchodilator response to salbutamol?

• Chest X-ray only
• Spirometry showing increase in FEV1 after inhaled salbutamol
• Serum salbutamol level measurement
• Complete blood count

Correct Answer: Spirometry showing increase in FEV1 after inhaled salbutamol

Q46. Which precaution is advised when using salbutamol in diabetic patients?

• No precautions are necessary
• Monitor blood glucose since salbutamol can cause hyperglycemia
• Stop insulin therapy when using salbutamol
• Switch to oral salbutamol to avoid blood glucose changes

Correct Answer: Monitor blood glucose since salbutamol can cause hyperglycemia

Q47. Which statement regarding inhaler storage and stability for salbutamol MDIs is correct?

• Keep MDIs at very high temperatures to preserve propellant
• Store at room temperature away from direct heat and sunlight and check dose counter
• Always refrigerate the inhaler
• Expose to sunlight before use to activate drug

Correct Answer: Store at room temperature away from direct heat and sunlight and check dose counter

Q48. Which of the following is a contraindication to salbutamol use?

• Known hypersensitivity to salbutamol or any component of the formulation
• Mild intermittent asthma needing rescue inhaler
• Exercise-induced bronchospasm prevented by pre-exercise inhalation
• Use in pregnancy when benefits outweigh risks

Correct Answer: Known hypersensitivity to salbutamol or any component of the formulation

Q49. In pharmacology exams, salbutamol is often categorized as which type of sympathomimetic?

• Indirect acting sympathomimetic that releases norepinephrine
• Mixed acting sympathomimetic with equal direct and indirect effects
• Direct acting beta-2 selective sympathomimetic
• Pure alpha-adrenergic agonist

Correct Answer: Direct acting beta-2 selective sympathomimetic

Q50. Which counseling point helps reduce systemic absorption and side effects of inhaled salbutamol?

• Swallow the dose after inhalation
• Rinse mouth after use and use a spacer where appropriate
• Use twice the recommended dose each time
• Hold the inhaler in the mouth without inhaling

Correct Answer: Rinse mouth after use and use a spacer where appropriate

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