Direct acting sympathomimetics – Bitolterol MCQs With Answer

Direct acting sympathomimetics like Bitolterol are important beta2-adrenergic agents in respiratory pharmacology and therapeutics. This concise introduction for B.Pharm students reviews Bitolterol’s role as a prodrug converted to colterol, its beta2 selectivity, mechanism of increasing intracellular cAMP, routes of administration (inhalation), clinical indications in acute and chronic asthma, metabolism by plasma esterases, and common adverse effects such as tremor and tachycardia. The content highlights comparisons with salbutamol/albuterol, key drug interactions, monitoring points and safety considerations. An evidence-based review of mechanism and safety helps exam readiness. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which statement best describes the primary mechanism of action of Bitolterol?

• It directly blocks muscarinic receptors on bronchial smooth muscle
• It is a prodrug converted to colterol, a selective beta2-adrenergic agonist
• It inhibits phosphodiesterase in airway epithelial cells
• It is an alpha1-adrenergic agonist causing bronchodilation

Correct Answer: It is a prodrug converted to colterol, a selective beta2-adrenergic agonist

Q2. Bitolterol is primarily administered by which route for asthma therapy?

• Oral tablets
• Intravenous infusion
• Inhalation (MDI or nebulizer)
• Topical application

Correct Answer: Inhalation (MDI or nebulizer)

Q3. The active metabolite of Bitolterol is:

• Terbutaline
• Colterol
• Salbutamol
• Isoproterenol

Correct Answer: Colterol

Q4. Which intracellular second messenger increases following beta2 receptor activation by colterol?

• IP3 (Inositol trisphosphate)
• cGMP (Cyclic GMP)
• cAMP (Cyclic AMP)
• Ca2+ (Intracellular calcium)

Correct Answer: cAMP (Cyclic AMP)

Q5. Compared with non-selective beta agonists, selective beta2 agonists like colterol produce less:

• Bronchodilation
• Hypoglycemia
• Cardiac beta1-mediated tachycardia at therapeutic doses
• Relaxation of bronchial smooth muscle

Correct Answer: Cardiac beta1-mediated tachycardia at therapeutic doses

Q6. Which enzyme system primarily converts Bitolterol to its active metabolite?

• CYP3A4 hepatic oxidation
• Plasma esterases
• Monoamine oxidase (MAO)
• Renal dehydrogenases

Correct Answer: Plasma esterases

Q7. A key clinical advantage of using Bitolterol as a prodrug is:

• Longer systemic half-life due to hepatic accumulation
• Decreased bitter taste in oral formulations
• Reduced local airway irritation and improved lung selectivity
• Guaranteed absence of cardiovascular effects

Correct Answer: Reduced local airway irritation and improved lung selectivity

Q8. Which adverse effect is commonly associated with beta2-agonists including Bitolterol?

• Hyperkalemia
• Tremor
• Dry mouth
• Urinary retention

Correct Answer: Tremor

Q9. Excessive beta2-agonist use can cause which electrolyte disturbance?

• Hyperkalemia
• Hypokalemia
• Hypernatremia
• Hyponatremia

Correct Answer: Hypokalemia

Q10. Bitolterol’s bronchodilator effect is mediated primarily by relaxation of which tissue?

• Bronchial smooth muscle
• Alveolar epithelium
• Pulmonary endothelial cells
• Intercostal muscles

Correct Answer: Bronchial smooth muscle

Q11. Which clinical indication is most appropriate for Bitolterol?

• Chronic obstructive gout
• Acute and chronic bronchospasm in asthma
• First-line therapy for pulmonary embolism
• Treatment of bacterial bronchitis

Correct Answer: Acute and chronic bronchospasm in asthma

Q12. Which drug interaction is clinically significant with beta2-agonists like Bitolterol?

• Concurrent use with beta-blockers reduces bronchodilatory effect
• Coadministration with antacids increases activity
• ACE inhibitors enhance beta2 selectivity
• Loop diuretics prevent metabolism of Bitolterol

Correct Answer: Concurrent use with beta-blockers reduces bronchodilatory effect

Q13. In pharmacology, tachyphylaxis to beta2 agonists refers to:

• Progressive receptor upregulation
• Rapid decrease in response after repeated dosing
• Permanent loss of drug effect after one dose
• Improved efficacy with chronic use

Correct Answer: Rapid decrease in response after repeated dosing

Q14. Compared to salbutamol (albuterol), Bitolterol is best described as:

• More selective for alpha receptors
• A prodrug that is converted to an active beta2 agonist
• An inhaled corticosteroid
• A long-acting beta2 agonist (LABA)

Correct Answer: A prodrug that is converted to an active beta2 agonist

Q15. Which physiologic effect occurs after beta2 receptor activation in bronchial smooth muscle?

• Increased intracellular calcium via IP3
• Activation of adenylate cyclase and increased cAMP
• Inhibition of guanylate cyclase and decreased cGMP
• Opening of sodium channels causing depolarization

Correct Answer: Activation of adenylate cyclase and increased cAMP

Q16. The onset of action for inhaled Bitolterol is typically:

• Within minutes (rapid onset)
• After several hours (delayed onset)
• After several days (cumulative onset)
• Immediate and permanent

Correct Answer: Within minutes (rapid onset)

Q17. Which adverse cardiovascular effect may be seen with excessive inhaled beta2-agonist use?

• Bradycardia
• Tachycardia and palpitations
• Hypotension without reflex changes
• Atrioventricular block type III

Correct Answer: Tachycardia and palpitations

Q18. Which patient population requires caution when prescribing beta2-agonists like Bitolterol?

• Patients with stable hypothyroidism
• Patients with severe coronary artery disease or arrhythmias
• Patients with controlled eczema
• Healthy young athletes with no comorbidities

Correct Answer: Patients with severe coronary artery disease or arrhythmias

Q19. The primary route of metabolism for Bitolterol’s prodrug moiety is:

• Renal glucuronidation
• Hydrolysis by plasma esterases
• Mitochondrial oxidation
• Sulfation in the liver

Correct Answer: Hydrolysis by plasma esterases

Q20. Which statement about tolerance to beta2 agonists is true?

• Tolerance cannot occur with inhaled agents
• Tolerance may develop with chronic frequent use, reducing effectiveness
• Tolerance increases bronchodilator potency over time
• Tolerance is immediately reversible after one dose

Correct Answer: Tolerance may develop with chronic frequent use, reducing effectiveness

Q21. Which adverse metabolic effect is associated with beta2 agonists?

• Hyperglycemia
• Hypoglycemia
• Increased insulin sensitivity
• Decreased gluconeogenesis

Correct Answer: Hyperglycemia

Q22. Which statement best describes selectivity of colterol at therapeutic doses?

• Highly selective for alpha2 receptors
• Selective for beta2 receptors with minimal beta1 effects at therapeutic doses
• Equally active at beta1 and beta2 receptors at low doses
• Selective for muscarinic M3 receptors

Correct Answer: Selective for beta2 receptors with minimal beta1 effects at therapeutic doses

Q23. Which monitoring parameter is most relevant when initiating high-dose inhaled beta2 agonists?

• Serum creatinine levels
• Blood glucose and serum potassium
• Prothrombin time
• Serum bilirubin

Correct Answer: Blood glucose and serum potassium

Q24. Which best describes a contra-indication or precaution for Bitolterol?

• Concomitant use of nonselective beta-blockers may antagonize action
• Concurrent therapy with inhaled corticosteroids is contraindicated
• Use in patients with type 1 diabetes is strictly prohibited
• Cannot be used with short-acting bronchodilators

Correct Answer: Concomitant use of nonselective beta-blockers may antagonize action

Q25. Which exam-style pharmacokinetic concept applies to Bitolterol as a prodrug?

• Prodrug approach may reduce local irritation and increase lung targeting
• Prodrug form is always more potent than active drug
• Prodrug is inactive in plasma and requires hepatic CYP metabolism exclusively
• Prodrug use eliminates the need for dosing adjustments

Correct Answer: Prodrug approach may reduce local irritation and increase lung targeting

Q26. Which adverse effect is least likely with inhaled selective beta2 agonists at standard doses?

• Tremor
• Reflex tachycardia
• Hypokalemia
• Severe hypertension from alpha1 stimulation

Correct Answer: Severe hypertension from alpha1 stimulation

Q27. Which pharmacologic class does Bitolterol belong to?

• Anticholinergic bronchodilator
• Beta2-adrenergic agonist (prodrug)
• Mast cell stabilizer
• Systemic corticosteroid

Correct Answer: Beta2-adrenergic agonist (prodrug)

Q28. In the event of hypokalemia caused by excessive beta2 stimulation, the immediate management includes:

• Administering oral or IV potassium as needed
• Infusing calcium channel blockers
• Starting aminophylline therapy
• Giving high-dose insulin

Correct Answer: Administering oral or IV potassium as needed

Q29. Which statement about inhaled delivery of Bitolterol is correct?

• Inhaled delivery directly targets airway receptors and reduces systemic exposure
• Inhaled route results in greater systemic side effects than oral administration
• Inhaled Bitolterol cannot achieve rapid bronchodilation
• Inhaled administration bypasses lung receptors and acts systemically only

Correct Answer: Inhaled delivery directly targets airway receptors and reduces systemic exposure

Q30. Which clinical situation requires caution because of potential interaction with beta2-agonists?

• Concurrent MAO inhibitor therapy may enhance sympathomimetic effects
• Concurrent use of topical antifungals increases bronchodilation
• Concurrent calcium supplements prolong duration of action
• Concurrent aspirin therapy prevents metabolism

Correct Answer: Concurrent MAO inhibitor therapy may enhance sympathomimetic effects

Q31. Which description fits the duration of action of Bitolterol when inhaled?

• Ultra-short acting for minutes only
• Short-acting, suitable for relief of acute bronchospasm
• Long-acting, once-daily controller
• Permanent effect requiring single dose

Correct Answer: Short-acting, suitable for relief of acute bronchospasm

Q32. Which structural or chemical property is relevant to Bitolterol being a prodrug?

• It contains ester linkages susceptible to hydrolysis
• It is a peptide that requires enzymatic cleavage in GI
• It is a metal-chelating agent activated in the kidney
• It lacks any functional groups for metabolism

Correct Answer: It contains ester linkages susceptible to hydrolysis

Q33. Which patient counseling point is appropriate for inhaled Bitolterol?

• Use the inhaler daily at fixed times as sole controller therapy
• Use as needed for relief of acute bronchospasm and follow proper inhaler technique
• Take with a high-fat meal to increase absorption
• Stop other inhalers immediately when starting Bitolterol

Correct Answer: Use as needed for relief of acute bronchospasm and follow proper inhaler technique

Q34. Which laboratory change may occur after large doses of beta2-agonists?

• Decreased blood glucose
• Increased serum potassium
• Decreased serum potassium
• Marked leukopenia

Correct Answer: Decreased serum potassium

Q35. Which is a pharmacodynamic consequence of beta2 receptor stimulation in the bronchi?

• Stimulation of mucus secretion and bronchoconstriction
• Smooth muscle relaxation and bronchodilation
• Platelet aggregation
• Fibroblast activation causing scarring

Correct Answer: Smooth muscle relaxation and bronchodilation

Q36. Which class of drugs should be used cautiously or avoided with Bitolterol due to antagonism?

• Beta-blockers (especially nonselective)
• Inhaled corticosteroids
• Mast cell stabilizers
• Leukotriene receptor antagonists

Correct Answer: Beta-blockers (especially nonselective)

Q37. For exam-style questions, which pharmacologic principle explains fewer systemic effects of inhaled prodrugs?

• First-pass hepatic activation increases systemic exposure
• Lung-targeted delivery and local conversion reduce systemic concentrations
• Oral bioavailability is always higher than inhaled
• Inhaled agents are not absorbed at all

Correct Answer: Lung-targeted delivery and local conversion reduce systemic concentrations

Q38. Which clinical finding suggests an exaggerated systemic beta2 effect?

• Peripheral vasodilation with reflex tachycardia
• Profound miosis
• Excessive salivation
• Severe urinary retention

Correct Answer: Peripheral vasodilation with reflex tachycardia

Q39. Which monitoring is most appropriate during an acute severe asthma attack treated with frequent beta2 agonist nebulization?

• Serial serum potassium and ECG monitoring if high doses used
• Daily liver function tests
• Monthly hemoglobin monitoring
• Immediate brain MRI

Correct Answer: Serial serum potassium and ECG monitoring if high doses used

Q40. Which statement about long-term use of short-acting beta2 agonists is correct?

• Overuse can worsen asthma control and risk exacerbations
• They prevent airway remodeling when used daily
• They have no tolerance potential with chronic use
• They are ideal sole therapy for persistent asthma

Correct Answer: Overuse can worsen asthma control and risk exacerbations

Q41. Which of the following is the most appropriate step if a patient using inhaled Bitolterol reports persistent tremor and palpitations?

• Increase the dose to overcome tolerance
• Assess inhaler technique and consider dose reduction or alternative therapy
• Stop all asthma medications immediately
• Switch to oral Bitolterol tablets

Correct Answer: Assess inhaler technique and consider dose reduction or alternative therapy

Q42. Which pharmacological property helps reduce systemic side effects of Bitolterol compared with systemic beta2 agonists?

• High oral bioavailability
• Prodrug conversion targeted in pulmonary tissues
• High lipid solubility causing accumulation
• Irreversible receptor binding

Correct Answer: Prodrug conversion targeted in pulmonary tissues

Q43. Which sign would indicate potentially life-threatening overdose of a beta2 agonist?

• Mild cough
• Severe tachyarrhythmia and hypotension
• Enhanced appetite
• Mild dizziness that resolves spontaneously

Correct Answer: Severe tachyarrhythmia and hypotension

Q44. Which exam-focused comparison is true: Bitolterol vs. terbutaline?

• Both are prodrugs requiring plasma esterases
• Bitolterol is a prodrug converted to colterol; terbutaline is an active beta2 agonist
• Terbutaline is an alpha agonist while Bitolterol is beta2 selective
• Both are long-acting inhaled corticosteroids

Correct Answer: Bitolterol is a prodrug converted to colterol; terbutaline is an active beta2 agonist

Q45. Which pharmacotherapeutic principle applies to using a prodrug bronchodilator?

• Prodrugs always increase systemic toxicity
• Prodrugs may improve pharmacokinetic or tolerability profiles by local activation
• Prodrugs are ineffective in inhaled form
• Prodrugs eliminate need for combination therapy

Correct Answer: Prodrugs may improve pharmacokinetic or tolerability profiles by local activation

Q46. Which side effect is most likely reduced by converting an active beta2 agonist into a prodrug for inhalation?

• Local bronchial smooth muscle relaxation
• Systemic cardiovascular stimulation
• Bronchial mucosal hydration
• Improved airway clearance

Correct Answer: Systemic cardiovascular stimulation

Q47. Which counseling advice improves deposition of inhaled Bitolterol in the lower airways?

• Inhale rapidly and hold breath for a second
• Use proper slow deep inhalation with a breath-hold after actuation
• Exhale forcefully immediately after inhalation
• Take the inhaler without priming or shaking

Correct Answer: Use proper slow deep inhalation with a breath-hold after actuation

Q48. Which laboratory abnormality should be anticipated in severe beta2-agonist overuse?

• Hyperkalemia and acidosis
• Hypokalemia and transient hyperglycemia
• Marked leukocytosis with left shift
• Severe hyponatremia

Correct Answer: Hypokalemia and transient hyperglycemia

Q49. Which therapeutic combination is commonly used for long-term asthma control, not solely for Bitolterol?

• Long-acting beta2 agonist plus inhaled corticosteroid
• Beta2 agonist plus systemic antibiotic daily
• Beta2 agonist plus intranasal decongestant
• Beta2 agonist alone as only long-term controller in all patients

Correct Answer: Long-acting beta2 agonist plus inhaled corticosteroid

Q50. In exam questions, which statement summarizes the clinical role of Bitolterol?

• An inhaled beta2 prodrug used for acute relief of bronchospasm with lung-targeted activation
• An oral anti-inflammatory agent for asthma maintenance
• A systemic beta1 agonist primarily for heart failure
• A leukotriene receptor antagonist used as first-line monotherapy

Correct Answer: An inhaled beta2 prodrug used for acute relief of bronchospasm with lung-targeted activation

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