What is the recommended dosing of Tamiflu (oseltamivir) for a patient with impaired renal function?

Tamiflu Renal Dosing

For patients with renal impairment, oseltamivir dosing must be reduced when creatinine clearance falls below 30 mL/min—the critical threshold is CrCl <30 mL/min, not higher values. 1

Standard Dosing (CrCl ≥30 mL/min)

• No dose adjustment is required for patients with CrCl ≥30 mL/min, including those with mild renal impairment 1
• Standard treatment: 75 mg orally twice daily for 5 days 1
• Standard prophylaxis: 75 mg orally once daily for at least 10 days following exposure 1
• Age alone (even >65 years) does not require dose adjustment if renal function is preserved 1

Moderate Renal Impairment (CrCl 10-30 mL/min)

Treatment dosing:

• 75 mg once daily for 5 days (reduce frequency from twice daily to once daily) 1, 2
• Alternative: 30 mg twice daily may be used 3

Prophylaxis dosing:

• 75 mg every other day for 10 days (5 total doses) 1, 2
• Alternative: 30 mg once daily for 10 days 2

Severe Renal Impairment (CrCl <10 mL/min)

For patients on hemodialysis:

• Treatment: 30 mg after each hemodialysis session 1
• Prophylaxis: 30 mg after every alternate hemodialysis session 1

For ESRD patients NOT on hemodialysis:

• Oseltamivir pharmacokinetics have not been adequately studied in this population 4
• Consider alternative therapy with zanamivir (see below) 1

Pharmacokinetic Rationale

• Oseltamivir carboxylate (the active metabolite) is eliminated >99% by renal excretion 4
• Exposure to oseltamivir carboxylate increases inversely proportional to declining renal function 4
• Renal clearance (18.8 L/h) exceeds glomerular filtration rate (7.5 L/h), indicating tubular secretion via organic anion transporter 4
• Hemodialysis contributes minimally to oseltamivir clearance 4

Alternative: Zanamivir for Renal Impairment

Zanamivir (inhaled) requires NO dose adjustment in any degree of renal impairment, making it an excellent alternative for patients with severe renal dysfunction 1

• Treatment: 10 mg (two inhalations) twice daily for 5 days 1
• Prophylaxis: 10 mg (two inhalations) once daily 1
• This applies to all levels of renal impairment, including ESRD 1

Critical Clinical Pearls

Common pitfall: Do not confuse the threshold—dose reduction is mandatory at CrCl <30 mL/min, not at higher values like 46 mL/min or 60 mL/min 1

Timing considerations:

• Treatment should be initiated within 48 hours of symptom onset for maximum effectiveness 2
• Early achievement of therapeutic concentrations is critical for efficacy 5

Tolerability:

• Administer with food to reduce gastrointestinal side effects (nausea/vomiting occur in ~10-15% of patients) 2
• Only ~1% of patients discontinue due to GI effects 2

Formulation options:

• Available as 30 mg, 45 mg, and 75 mg capsules 2
• Oral suspension: 6 mg/mL when reconstituted 2
• Capsules can be opened and mixed with liquid if swallowing is difficult 2

Dosing Algorithm Summary

1. Calculate creatinine clearance (not just GFR) 1
2. If CrCl ≥30 mL/min: Use standard dosing (75 mg twice daily for treatment, 75 mg once daily for prophylaxis) 1
3. If CrCl 10-30 mL/min: Reduce to 75 mg once daily for treatment OR 75 mg every other day for prophylaxis 1, 2
4. If CrCl <10 mL/min on hemodialysis: Use 30 mg per dialysis cycle for treatment OR 30 mg every alternate cycle for prophylaxis 1
5. If CrCl <10 mL/min NOT on dialysis: Consider zanamivir instead (no dose adjustment needed) 1