Za Pharmacy
Drugs, Supplies and Delivery
Fexofenadine
Fexofenadine is a safe, non-sedating option for allergic rhinitis and urticaria, with minimal drug interactions and CNS effects. Adherence to BNF dosing guidelines, avoidance of interacting substances, and dose adjustments in renal impairment optimize therapeutic outcomes.
Fexofenadine is a second-generation antihistamine that selectively antagonizes peripheral H₁ histamine receptors. Unlike first-generation antihistamines, it minimally crosses the blood-brain barrier, reducing central nervous system (CNS) effects such as sedation. Its mechanism involves:
- Competitive Inhibition: Blocks histamine binding to H₁ receptors, preventing allergic responses like vasodilation, bronchoconstriction, and itching.
- Peripheral Selectivity: Avoids interaction with CNS receptors, minimizing drowsiness (Lippincott).
Fexofenadine is approved for:
- Allergic Rhinitis:
- Seasonal (hay fever) and perennial allergic rhinitis.
- Chronic Idiopathic Urticaria:
- Reduces itching and hives.
- Off-Label Uses:
- Mild allergic skin reactions (e.g., insect bites).
Adults and Adolescents (≥12 years):
- Allergic Rhinitis: 120 mg once daily.
- Chronic Urticaria: 180 mg once daily.
Children (6–11 years):
- Allergic Rhinitis/Urticaria: 30 mg twice daily.
Renal Impairment:
- Creatinine Clearance <30 mL/min: Reduce dose to 60 mg once daily (BNF).
Administration Tips:
- Take with water; avoid fruit juices (e.g., grapefruit, orange) that may impair absorption.
Separate from antacids (aluminum/magnesium) by ≥2 hours
Fexofenadine is generally well-tolerated. Common and rare effects include:
- Common: Headache (7%), nausea (2%), dizziness (1%).
- Rare: Fatigue, dry mouth, hypersensitivity reactions (rash, angioedema).
- Cardiac Safety: No significant QT prolongation (unlike terfenadine) (Lange).
- Contraindications:
- Hypersensitivity to fexofenadine or components.
- Pregnancy/Lactation:
- Pregnancy: Use only if benefits outweigh risks (limited human data).
- Lactation: Excreted in breast milk; use with caution (BNF).
- Renal Impairment: Dose adjustment required (see above).
- Pediatric Use: Not recommended for children <6 years.
Fexofenadine interacts with:
- P-glycoprotein Inhibitors:
- Erythromycin, Ketoconazole: Increase fexofenadine plasma levels (monitor for side effects).
- Antacids: Reduce absorption (administer 2 hours apart).
- Fruit Juices: Grapefruit, apple, orange juices decrease bioavailability (Lippincott).
- Generic: Fexofenadine Hydrochloride.
- Brand Names: Allegra® (US), Telfast® (UK, AU), Fexidine® (IN).
