What is the recommended dosage of fexofenadine (Allegra) for adults and children with normal and impaired renal function?

Recommended Dosage of Fexofenadine (Allegra)

For adults and children with allergic rhinitis or chronic idiopathic urticaria, fexofenadine should be dosed at 60 mg twice daily or 180 mg once daily for normal renal function, and reduced to 60 mg once daily in patients with decreased renal function. 1

Adult Dosing

• Normal renal function:

  • 60 mg twice daily OR
  • 180 mg once daily

• Impaired renal function:

  • 60 mg once daily as the starting dose 1
  • No specific creatinine clearance threshold is specified in the FDA label, but dose reduction is recommended for any degree of renal impairment

Pediatric Dosing

• Children 12 years and older:

  • Same as adult dosing (60 mg twice daily or 180 mg once daily)
  • For impaired renal function: 60 mg once daily

• Children 6-11 years:

  • 30 mg twice daily
  • For impaired renal function: 30 mg once daily 1

• Children under 6 years:

  • Not FDA approved for this age group

Administration

• Should be taken with water
• Can be taken without regard to meals, though taking with food may improve gastrointestinal tolerability 2
• No dosage adjustment is required based on age alone

Clinical Efficacy and Safety Considerations

Fexofenadine has been shown to be effective in both seasonal allergic rhinitis and chronic idiopathic urticaria with a safety profile similar to placebo 2. Clinical studies have demonstrated:

• Significant improvement in total symptom scores in both adults and children with allergic rhinitis 3, 4
• No dose-related increase in sedation, even at doses up to 11 times the recommended therapeutic dose 5
• No clinically significant drug interactions identified 2
• No cardiotoxicity concerns, unlike some older antihistamines

Common Pitfalls to Avoid

1. Failure to adjust dosage in renal impairment: Always reduce the dose in patients with decreased renal function to prevent drug accumulation.

2. Incorrect pediatric dosing: Children 6-11 years require half the adult dose (30 mg twice daily), not the full adult dose.

3. Drug interactions: While no clinically significant drug interactions have been identified, be aware that antacids containing aluminum or magnesium may reduce absorption of fexofenadine if taken simultaneously.

4. Overdosing: Despite fexofenadine's excellent safety profile, there's no evidence that exceeding the recommended doses provides additional therapeutic benefit.

Fexofenadine is a highly specific H1-receptor antagonist that provides effective symptom relief while maintaining a safety profile comparable to placebo, making it an excellent choice for patients requiring an antihistamine without sedative effects.