Oseltamivir Dosing for CrCl 47 mL/min
For a patient with CrCl 47 mL/min, use the standard oseltamivir dose of 75 mg twice daily for treatment or 75 mg once daily for prophylaxis—no dose adjustment is required. 1, 2
Critical Threshold for Dose Adjustment
- The key threshold for oseltamivir dose reduction is CrCl <30 mL/min, not 46-47 mL/min. 1, 3
- Your patient with CrCl 47 mL/min falls well above this threshold and should receive full-dose therapy. 1, 2
- Multiple guidelines and the FDA label consistently establish 30 mL/min as the cutoff, not higher values like 46 or 60 mL/min. 1, 3
Standard Dosing Regimen (CrCl ≥30 mL/min)
For Treatment:
- 75 mg orally twice daily for 5 days 1, 2, 4
- Must be initiated within 48 hours of symptom onset for maximum benefit 2, 4
- Can be taken with or without food, though administration with meals reduces gastrointestinal side effects (nausea/vomiting occur in 10-15% of patients) 2, 4
For Prophylaxis:
- 75 mg orally once daily for 10 days after exposure 1, 2, 4
- Should be started within 48 hours of exposure to an infected individual 2
Pharmacokinetic Rationale
- The FDA label demonstrates that oseltamivir carboxylate (the active metabolite) exposure is inversely proportional to declining renal function. 3
- At CrCl 30-60 mL/min (which includes your patient at 47 mL/min), simulated median exposures with standard 75 mg twice-daily dosing achieve therapeutic trough concentrations (Cmin) of 180 ng/mL and AUC48 of 12,008 ng·h/mL—comparable to patients with normal renal function. 3
- Renal clearance of oseltamivir carboxylate (18.8 L/h) exceeds glomerular filtration rate, indicating tubular secretion contributes to elimination, but this mechanism remains adequate at CrCl 47 mL/min. 3, 5
Common Pitfall to Avoid
- Do not confuse the 30 mL/min threshold with higher cutoffs (such as 60 mL/min) that appear in some older literature or general renal dosing references. 1
- The well-established guideline and FDA-approved threshold is specifically CrCl <30 mL/min for dose reduction. 1, 3
- Some clinicians mistakenly reduce doses at CrCl 30-60 mL/min, which results in subtherapeutic concentrations and reduced efficacy, particularly problematic since early therapeutic concentrations are critical for influenza treatment. 6
When Dose Reduction IS Required (For Reference)
Only if CrCl drops to 10-30 mL/min:
- Treatment: 75 mg once daily (not twice daily) for 5 days 7, 1, 3
- Prophylaxis: 30 mg once daily OR 75 mg every other day for 10 days 7, 1, 3
For CrCl <10 mL/min or hemodialysis: