What is the recommended dosing of Fexofenadine (Fenofaxadine) for patients with End-Stage Renal Disease (ESRD)?

Fexofenadine Dosing in ESRD Patients

For adults with end-stage renal disease (ESRD), start fexofenadine at 60 mg once daily (rather than the standard 60 mg twice daily or 180 mg once daily), and administer the dose after hemodialysis sessions on dialysis days. 1

Dosing Algorithm for ESRD

Standard Dose Reduction

• Adults and children ≥12 years: Reduce from standard dosing (60 mg twice daily or 180 mg once daily) to 60 mg once daily as the starting dose in patients with decreased renal function 1
• Children 6-11 years: Reduce from standard dosing (30 mg twice daily) to 30 mg once daily as the starting dose in pediatric patients with decreased renal function 1
• This applies to both seasonal allergic rhinitis and chronic idiopathic urticaria indications 1

Timing with Hemodialysis

• Administer fexofenadine after hemodialysis sessions on dialysis days to prevent premature drug removal and ensure adequate therapeutic levels 2
• This timing principle is consistent across medications requiring renal dose adjustment in ESRD patients 3, 4, 2

Rationale for Dose Reduction

Pharmacokinetic Considerations

• Fexofenadine undergoes renal excretion, and impaired renal function in ESRD leads to accumulation of the parent drug in the body 5
• ESRD affects both renal excretion and may alter plasma protein binding, which influences drug distribution and elimination 5
• The 50% dose reduction (from twice daily to once daily dosing) accounts for the significantly reduced drug clearance in ESRD 1

Safety Profile in Renal Impairment

• Fexofenadine has been specifically studied and shown to be well tolerated in subjects with renal impairment 6
• The drug maintains a high margin of safety even in patients with decreased renal function 6
• Unlike some antihistamines, fexofenadine is truly non-sedating and does not show dose-related increases in sedation, which is particularly important when dosing adjustments are made 6

Critical Pitfalls to Avoid

• Do not use standard adult doses (60 mg twice daily or 180 mg once daily) without dose reduction in ESRD patients, as this increases risk of drug accumulation 1, 5
• Avoid administering before dialysis sessions, which would result in premature drug removal and subtherapeutic levels 2
• Do not assume all nonrenally cleared drugs are safe at standard doses in ESRD, as end-stage renal disease can also affect nonrenal clearance pathways including hepatic metabolism 7
• Monitor for dosing errors, which are among the most common problems in patients with renal failure, particularly in non-tertiary care settings 8

Monitoring Recommendations

• Reassess clinical response within 48-72 hours of initiating therapy 2
• Adjust dosing if there is inadequate symptom control or evidence of drug accumulation 2
• Consider that dosage adjustment based solely on GFR may not always be appropriate, as net renal excretion involves glomerular filtration, tubular secretion, and tubular reabsorption 5