Pharmacology · patient case question
What is cetirizine prescribed for?
Patient case: Medication review before an extraction
Patient: Male, 66 years old
Chief complaint: “This broken tooth needs to come out.”
History: Coronary stent placed two years ago; on aspirin 81 mg and clopidogrel. Seasonal allergic rhinitis, takes cetirizine. Generalised anxiety, takes buspirone.
Findings: Non-restorable tooth #30. No swelling. Blood pressure 128/78 mmHg.
Show answer and explanation
Correct answer: B. Seasonal allergic rhinitis
- A. Insomnia is sometimes self-treated with first-generation antihistamines such as diphenhydramine, precisely because they are sedating. Cetirizine is chosen for the opposite property.
- B. CORRECT. Cetirizine is a SECOND-GENERATION H1 antihistamine used for seasonal and perennial allergic rhinitis and for urticaria. Second-generation agents cross the blood-brain barrier poorly, so sedation and anticholinergic effects are much less than with first-generation drugs.
- C. Reflux is treated with proton pump inhibitors such as omeprazole or with H2-receptor blockers such as famotidine. H2 receptors are gastric; H1 receptors mediate allergy.
- D. Motion sickness is treated with scopolamine, an antimuscarinic, or with first-generation antihistamines such as dimenhydrinate and meclizine that do enter the CNS.
Note: Know the split: first-generation — diphenhydramine, chlorpheniramine, promethazine — are sedating and anticholinergic, causing xerostomia. Second-generation — cetirizine, loratadine, fexofenadine — are not.