Cetirizine MCQs With Answer

Cetirizine MCQs With Answer

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Cetirizine MCQs With Answer introduces B. Pharm students to cetirizine’s pharmacology, mechanism, pharmacokinetics, therapeutic uses, adverse effects, interactions, and dosage considerations. This concise, keyword-rich guide covers cetirizine as a second-generation H1 antihistamine, its inverse agonist action at H1 receptors, low central nervous system penetration, renal excretion, minimal CYP metabolism, and clinical roles in allergic rhinitis and chronic urticaria. Emphasis is placed on safety profiles, pediatric and pregnancy considerations, dosing adjustments in renal impairment, and comparisons with other antihistamines. The questions probe deeper into receptor selectivity, formulation, and clinical decision-making to prepare you for exams and practice. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which best describes the primary mechanism of action of cetirizine?

  • H2 receptor antagonist
  • H1 receptor inverse agonist
  • Leukotriene receptor antagonist
  • Cyclooxygenase inhibitor

Correct Answer: H1 receptor inverse agonist

Q2. Cetirizine is classified as which generation of antihistamines?

  • First-generation antihistamine
  • Second-generation antihistamine
  • Third-generation antihistamine
  • Non-sedating opioid antagonist

Correct Answer: Second-generation antihistamine

Q3. Compared with first-generation antihistamines, cetirizine’s central nervous system sedation is generally:

  • Markedly greater
  • About the same
  • Lower, but more than some second-generation agents like fexofenadine
  • Non-existent

Correct Answer: Lower, but more than some second-generation agents like fexofenadine

Q4. What is the approximate oral bioavailability of cetirizine in adults?

  • Less than 10%
  • Approximately 30%
  • Approximately 70%
  • Nearly 100%

Correct Answer: Approximately 70%

Q5. The typical elimination half-life of cetirizine in healthy adults is closest to:

  • 1–2 hours
  • 4–6 hours
  • 8–10 hours
  • 24–48 hours

Correct Answer: 8–10 hours

Q6. Which statement correctly describes cetirizine metabolism and excretion?

  • Extensive hepatic metabolism with biliary excretion as the main route
  • Minimal hepatic metabolism and primarily renal excretion of unchanged drug
  • Extensive conversion to active metabolites by CYP2D6
  • Eliminated mainly via pulmonary exhalation

Correct Answer: Minimal hepatic metabolism and primarily renal excretion of unchanged drug

Q7. Levocetirizine in relation to cetirizine is:

  • An inactive prodrug of cetirizine
  • The S-enantiomer with less potency
  • The R-enantiomer (active enantiomer) with greater H1 affinity
  • A metabolite that causes increased sedation

Correct Answer: The R-enantiomer (active enantiomer) with greater H1 affinity

Q8. Cetirizine is generally not recommended for infants younger than:

  • 2 weeks
  • 6 months
  • 2 years
  • 6 years

Correct Answer: 6 months

Q9. The most commonly reported adverse effect of cetirizine is:

  • Severe anticholinergic toxicity
  • Hepatotoxicity
  • Somnolence (drowsiness)
  • Excessive stimulation and insomnia

Correct Answer: Somnolence (drowsiness)

Q10. Regarding cardiac safety at therapeutic doses, cetirizine is known to have:

  • High risk of torsades de pointes due to QT prolongation
  • Significant QT prolongation similar to terfenadine
  • Minimal effect on QT interval at recommended doses
  • Contraindication in all patients with any heart disease

Correct Answer: Minimal effect on QT interval at recommended doses

Q11. Which interaction is clinically important with cetirizine?

  • Cetirizine potentiates anticoagulants causing bleeding
  • Concurrent alcohol use may increase CNS depression
  • Grapefruit juice markedly increases cetirizine levels
  • Concurrent use with iron supplements doubles cetirizine absorption

Correct Answer: Concurrent alcohol use may increase CNS depression

Q12. Historically, cetirizine’s pregnancy safety category was classified as:

  • Category X (contraindicated)
  • Category D (evidence of risk)
  • Category B (no evidence of risk in animal studies)
  • Category C (risk cannot be ruled out)

Correct Answer: Category B (no evidence of risk in animal studies)

Q13. Cetirizine’s effect on nasal congestion (obstruction) is best described as:

  • Highly effective as a decongestant
  • Directly vasoconstrictive like pseudoephedrine
  • Limited effect; mainly reduces sneezing, itching, and rhinorrhea
  • Causes rebound congestion with chronic use

Correct Answer: Limited effect; mainly reduces sneezing, itching, and rhinorrhea

Q14. The main route of elimination for cetirizine is:

  • Fecal excretion after extensive biliary secretion
  • Renal excretion of unchanged drug
  • Metabolism to inactive metabolites by CYP2C9 and fecal elimination
  • Exhaled as CO2 after hepatic metabolism

Correct Answer: Renal excretion of unchanged drug

Q15. Which statement about cetirizine and CYP3A4 inhibitors (e.g., ketoconazole) is correct?

  • CYP3A4 inhibitors dramatically increase cetirizine toxicity
  • Cetirizine is extensively metabolized by CYP3A4, so inhibitors double its half-life
  • Cetirizine undergoes minimal CYP3A4 metabolism and shows limited interaction
  • CYP3A4 inducers are contraindicated with cetirizine

Correct Answer: Cetirizine undergoes minimal CYP3A4 metabolism and shows limited interaction

Q16. Recommended dosing frequency for adults for allergic rhinitis is typically:

  • Every 4–6 hours
  • Once daily
  • Three times daily
  • Continuous infusion

Correct Answer: Once daily

Q17. Compared to many first-generation antihistamines, cetirizine’s antimuscarinic (anticholinergic) effects are:

  • Markedly stronger, causing dry mouth and urinary retention
  • Minimal, with low anticholinergic burden
  • Equivalent to atropine
  • Strong enough to treat motion sickness

Correct Answer: Minimal, with low anticholinergic burden

Q18. Chemically, cetirizine is best classified as which derivative?

  • Piperazine derivative related to hydroxyzine
  • Benzodiazepine derivative
  • Phenothiazine derivative
  • Amide local anesthetic derivative

Correct Answer: Piperazine derivative related to hydroxyzine

Q19. The onset of clinical action for cetirizine after oral administration is typically:

  • Within 15 minutes
  • Within 1 hour
  • After 24 hours
  • Only after several days of dosing

Correct Answer: Within 1 hour

Q20. Cetirizine is an approved therapy for which dermatologic allergic condition?

  • Chronic idiopathic urticaria
  • Psoriasis vulgaris
  • Contact dermatitis requiring systemic steroids
  • Severe bullous pemphigoid

Correct Answer: Chronic idiopathic urticaria

Q21. In overdose, the most likely clinical feature of cetirizine toxicity is:

  • Profound cholinergic crisis
  • Severe liver failure
  • Drowsiness and CNS depression
  • Immediate renal shutdown

Correct Answer: Drowsiness and CNS depression

Q22. Common available oral formulations of cetirizine include:

  • Intravenous injection only
  • Topical cream and ointment
  • Tablets, chewable tablets, and oral syrup
  • Transdermal patch only

Correct Answer: Tablets, chewable tablets, and oral syrup

Q23. Cetirizine’s plasma protein binding is best described as:

  • Negligible (<10%)
  • Moderate (~50%)
  • High (~90% or more)
  • Complete (100%)

Correct Answer: High (~90% or more)

Q24. Which enzyme system is primarily responsible for cetirizine metabolism?

  • Extensive CYP3A4-dependent metabolism
  • Predominantly non-CYP pathways with minimal hepatic metabolism
  • Metabolism exclusively by MAO-A
  • Rapid hydrolysis by plasma esterases

Correct Answer: Predominantly non-CYP pathways with minimal hepatic metabolism

Q25. Dose adjustment of cetirizine is required in which condition?

  • Severe renal impairment
  • Mild seasonal allergic rhinitis
  • Uncomplicated mild hepatic steatosis
  • Controlled hypertension

Correct Answer: Severe renal impairment

Q26. Compared to racemic cetirizine, levocetirizine shows:

  • Lower affinity for H1 receptors
  • Higher potency and often lower required dose
  • Complete lack of antihistaminic activity
  • More anticholinergic side effects

Correct Answer: Higher potency and often lower required dose

Q27. Cetirizine reduces histamine-mediated symptoms primarily by blocking:

  • H3 receptors in the CNS
  • H1 receptors on peripheral blood vessels and sensory nerves
  • Histamine synthesis in mast cells
  • Leukotriene B4 receptors

Correct Answer: H1 receptors on peripheral blood vessels and sensory nerves

Q28. Does cetirizine act as a mast cell stabilizer to prevent degranulation?

  • Yes, it is a primary mast cell stabilizer
  • No, it does not have significant mast cell stabilizing properties
  • Only when given intravenously
  • Yes, but only in pediatric patients

Correct Answer: No, it does not have significant mast cell stabilizing properties

Q29. Which statement about cetirizine and motion sickness is correct?

  • Cetirizine is a first-line agent for motion sickness
  • Cetirizine is highly effective due to strong central anticholinergic effects
  • Cetirizine is not effective for motion sickness compared with first-generation antihistamines
  • Cetirizine must be combined with scopolamine to treat motion sickness

Correct Answer: Cetirizine is not effective for motion sickness compared with first-generation antihistamines

Q30. Combining cetirizine with other central nervous system depressants may result in:

  • Reduced antihistaminic efficacy
  • Decreased plasma concentration of cetirizine
  • Additive sedation and enhanced CNS depression
  • Complete antagonism of sedative effects

Correct Answer: Additive sedation and enhanced CNS depression

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