What is the recommended dose of fexofenadine (Allegra) for a patient with moderate impaired renal function (GFR of 40)?

Recommended Dosage of Fexofenadine for Patients with GFR of 40

For patients with moderate renal impairment (GFR of 40 mL/min/1.73m²), the recommended dose of fexofenadine (Allegra) is 60 mg once daily. 1

Dosing Considerations in Renal Impairment

• The FDA drug label specifically recommends a starting dose of 60 mg once daily for adult patients with decreased renal function, which includes patients with a GFR of 40 mL/min/1.73m² 1
• For pediatric patients aged 6-11 years with decreased renal function, the recommended dose is 30 mg once daily 1
• A GFR of 40 mL/min/1.73m² falls into the moderate renal impairment category (GFR 30-59 mL/min/1.73m²), requiring dose adjustment 2

Pharmacokinetic Considerations

• Fexofenadine is primarily eliminated through renal excretion, making dose adjustment necessary in patients with decreased kidney function 3
• Unlike many other medications that require substantial dose adjustments in renal impairment, fexofenadine requires a simple reduction in dosing frequency rather than a complex dose calculation 1, 4
• The KDOQI guidelines emphasize the importance of taking GFR into account when dosing medications, particularly for those primarily eliminated by the kidneys 2

Safety Profile in Renal Impairment

• Fexofenadine has been shown to be well-tolerated in subjects with renal impairment when appropriate dose adjustments are made 4
• The safety profile of properly dosed fexofenadine in patients with renal impairment is similar to that observed in patients with normal renal function 4
• Unlike some medications that require extensive monitoring in renal impairment, fexofenadine with appropriate dose adjustment does not require additional monitoring beyond routine care 4, 3

Clinical Application

• For chronic conditions like seasonal allergic rhinitis or chronic idiopathic urticaria, the once-daily reduced dose of 60 mg provides adequate symptom control while minimizing potential adverse effects 1
• The dose reduction from the standard 60 mg twice daily or 180 mg once daily to 60 mg once daily accounts for the decreased drug clearance in patients with moderate renal impairment 1, 5
• If the patient is taking other medications, be aware that fexofenadine has minimal drug interactions, which is advantageous in patients with renal impairment who may be on multiple medications 4

Common Pitfalls to Avoid

• Avoid prescribing the standard dose (60 mg twice daily or 180 mg once daily) to patients with renal impairment, as this may lead to drug accumulation 1, 3
• Do not confuse fexofenadine with other antihistamines that may have different renal dosing requirements 4
• Remember that during acute illness that may further compromise renal function, temporary discontinuation of renally excreted medications may be necessary to prevent adverse effects 2