Fexofenadine

 

1. Generic Name & Brand Names

• Generic Name: Fexofenadine

• Common Brands:

  • Allegra® (Global)

  • Telfast® (EU/Australia)

  • Fexidine® (India)

  • Aller-Relief® (store brands)

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2. Dosage Forms

• Oral:

  • Tablets (30 mg, 60 mg, 120 mg, 180 mg)

  • Orally Disintegrating Tablets (ODT, 30 mg)

  • Liquid Suspension (6 mg/mL)

• No topical/injectable forms

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3. Drug Class

• Active Metabolite of Terfenadine

• Second-Generation H₁ Antihistamine

• Non-sedating (negligible CNS penetration)

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4. Uses

• Seasonal Allergic Rhinitis (Hay Fever):

  • Sneezing, rhinorrhea, itchy eyes/nose

• Chronic Idiopathic Urticaria:

  • Hives (>6 weeks duration)

• Off-label: Mild atopic dermatitis itch

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5. Side Effects

Common (1-5%)	Rare (<1%)
Headache	Tachycardia
Nausea	Hypersensitivity rash
Dyspepsia	Drowsiness (0.2%)
Back pain	Hepatotoxicity
Minimal sedation	Anaphylaxis

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6. Critical Warnings

• Drug Interactions:

  • ⚠️ Avoid with Fruit Juices: Apple/orange/grapefruit ↓ absorption by 30-40% (take with water only).

  • ⚠️ Antacids: Aluminum/magnesium-based ↓ absorption (separate by 2+ hours).

  • ⚠️ P-glycoprotein Inhibitors: Erythromycin/ketoconazole ↑ fexofenadine levels.

• Contraindications:

  • Hypersensitivity to fexofenadine/terfenadine

• Renal Impairment:

  • ↓ Dose if CrCl <80 mL/min (see dosing table).

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7. How to Take

Indication	Adults/≥12 yrs	Children 6-11 yrs
Seasonal Allergies	180 mg once daily	30 mg twice daily
Chronic Urticaria	180 mg once daily	30 mg twice daily
Renal Dosing (CrCl <80):	60 mg once daily	Consult pediatrician

• Key Notes:

  • Take 1 hour before or 2 hours after fruit juice/antacids.

  • Onset: 1-2 hours; Peak effect: 2-3 hours; Duration: 24 hours.

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8. Missed Dose

• Take ASAP if <6 hours late

• Skip if >6 hours; resume next dose

• Never double dose

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9. Overdose

• Symptoms: Dizziness, tachycardia, dry mouth

• Management:

  • Symptomatic treatment (no specific antidote)

  • Dialysis ineffective (80% protein-bound)

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10. Storage

• Temperature: 15-30°C (59-86°F)

• Humidity: Keep ODT in blister until use

• Liquid: Discard after 6 months post-opening

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Critical Safety Notes:

⚠️ Food/Juice Interaction:

• Fruit juices reduce bioavailability by altering OATP transporters. Take with water only.
  ⚠️ Renal Adjustment:

• Mandatory for CrCl <80 mL/min:

  • *CrCl 50-79:* 60 mg daily

  • *CrCl 10-49:* 60 mg every other day
    ⚠️ Pediatric Use:

• Approved for ≥6 years (tablets), ≥2 years (liquid) - avoid adult doses in children.
  ⚠️ Driving Safety:

• 0.2% sedation risk - safer than cetirizine/levocetirizine for high-alert tasks.

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Fexofenadine vs. Other Antihistamines

Feature	Fexofenadine	Cetirizine	Loratadine
Standard Dose	180 mg daily	10 mg daily	10 mg daily
Onset	1-2 hours	30-60 min	1-3 hours
Fruit Juice Int.	Severe	None	Minimal
Renal Adjustment	Required	Required	Not required
Pregnancy	Category C	Category B	Category B

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Clinical Tips:

✅ Optimal Timing: Take at night for next-day pollen protection (peaks at 12h post-dose).
✅ Combination Therapy: Pair with intranasal steroids (e.g., fluticasone) for nasal congestion.
❌ Avoid in Severe Renal Impairment: Contraindicated if CrCl <10 mL/min.

OTC Status: Available without prescription in most countries for ages 6+.

📊 Efficacy Data:

• 180 mg reduces allergy symptoms by 70% vs. placebo (J Allergy Clin Immunol).

• Superior to loratadine for nasal congestion relief (Ann Allergy Asthma Immunol).

Prescribing Insight: First-choice for patients needing zero sedation or those with hepatic impairment (no liver metabolism). Always screen for renal function!