Medication review before an extraction

Correct answer: C. Proceed with no modification to either drug

• A. Stopping both drugs compounds the same error. Any decision to alter antiplatelet therapy belongs to the prescribing cardiologist, not the dentist, and is reserved for major surgery.
• B. A coronary stent is not an indication for antibiotic prophylaxis under AHA guidelines. Prophylaxis covers prosthetic valves, previous endocarditis, specified congenital heart disease and transplant valvulopathy.
• C. CORRECT. Dual antiplatelet therapy is NOT interrupted for routine dental extractions. The bleeding is minor, predictable and controllable with local measures — pressure, sutures, oxidised cellulose or gelatin sponge, and tranexamic acid mouthwash if needed. Interrupting therapy in a patient with a coronary stent risks STENT THROMBOSIS, which carries substantial mortality. The risk calculus is not close.
• D. Stopping clopidogrel for five days would restore platelet function but exposes the patient to a catastrophic thrombotic risk for a problem that local haemostasis handles.

Note: Plan for local haemostasis in advance rather than reacting to bleeding. Schedule earlier in the day and earlier in the week so any problem can be reviewed.

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.

Correct answer: B. No modification is required

• A. There is no basis for reducing anaesthetic dose. Dose limits are governed by weight and by cardiovascular and hepatic status.
• B. CORRECT. Cetirizine has no clinically meaningful interaction with local anaesthetics, vasoconstrictors, analgesics or antibiotics used in dentistry, and does not affect haemostasis or healing. No modification is needed. The only practical note is that mild xerostomia can occur, though far less than with first-generation agents.
• C. Epinephrine restriction applies to uncontrolled hyperthyroidism, unstable cardiovascular disease, cocaine or methamphetamine use, and to non-selective beta-blocker therapy — not to antihistamines.
• D. Prophylaxis is determined by cardiac and immune status, not by antihistamine use.

Correct answer: C. Anxiolytic

• A. Antipsychotics such as haloperidol, risperidone and olanzapine act primarily on dopamine D2 receptors and carry extrapyramidal effects, including tardive dyskinesia relevant to oral function.
• B. SSRIs such as fluoxetine and sertraline are also used in generalised anxiety, but buspirone is not an SSRI — it does not inhibit serotonin reuptake.
• C. CORRECT. Buspirone is a non-benzodiazepine ANXIOLYTIC, acting as a partial agonist at 5-HT1A receptors. Its clinical profile is distinctive: it does NOT sedate, does not potentiate alcohol or other CNS depressants, carries no dependence or withdrawal liability, and has NO acute effect — it needs two to four weeks to work, so it is unsuitable for situational or procedural anxiety.
• D. Antiepileptics such as phenytoin, carbamazepine and valproate work on ion channels or GABA transmission. Phenytoin is the one with the notable oral effect, gingival enlargement.

Note: Clinically useful contrast: a benzodiazepine such as triazolam is what you would use for procedural sedation because it acts within an hour. Buspirone would do nothing on the day.