What is the recommended dose of cefoxitin (Cefoxitin) for pediatric patients with impaired renal function and suspected infection?

Cefoxitin Dosing for Pediatric Patients with Renal Impairment

For pediatric patients aged 3 months and older with suspected infection and impaired renal function, administer cefoxitin at 150 mg/kg/day divided into 3-4 doses (maximum 12 g/day) intravenously, with dose reduction and interval extension based on creatinine clearance following adult renal dosing guidelines. 1, 2

Standard Pediatric Dosing (Normal Renal Function)

• Children ≥3 months: 150 mg/kg/day divided into 3-4 doses (maximum 12 g/day) by intravenous infusion 1
• Children <3 months: No specific recommendation exists; cefoxitin should be avoided in this age group unless no alternative exists 2
• Doses >2 grams must be administered by intravenous infusion diluted in sodium chloride 0.9% or glucose 5% 1

Renal Impairment Dosing Algorithm

Step 1: Calculate Creatinine Clearance

Use the Schwartz formula for pediatric patients or the Cockcroft-Gault formula (adjusted for pediatric weight) to estimate creatinine clearance 2

Step 2: Apply Dose Modifications

After an initial loading dose of 1-2 grams (or age-appropriate equivalent): 2

• CrCl 30-50 mL/min: 1-2 grams every 8-12 hours 2
• CrCl 10-29 mL/min: 1-2 grams every 12-24 hours 2
• CrCl 5-9 mL/min: 0.5-1 gram every 12-24 hours 2
• CrCl <5 mL/min: 0.5-1 gram every 24-48 hours 2

Step 3: Hemodialysis Considerations

• Give loading dose of 1-2 grams after each hemodialysis session 2
• Follow maintenance dosing per creatinine clearance table above 2

Important Clinical Considerations

Nephrotoxicity Risk

• Increased nephrotoxicity when combined with aminoglycosides or furosemide—monitor renal function closely 1
• Probenecid reduces renal excretion of cefoxitin, resulting in increased and prolonged serum levels 1

Monitoring Requirements

• Perform routine toxicity monitoring (FBC, U&Es, LFTs) intermittently throughout treatment 1
• Critical caveat: Cefoxitin interferes with Jaffé method creatinine assays, producing falsely elevated creatinine values—use enzymatic creatinine assays when available 1

Serious Adverse Effects to Monitor

• Acute renal failure and toxic nephropathy (rare) 1
• Seizures (particularly in renal impairment with inadequate dose adjustment) 1
• Pseudomembranous colitis 1
• Hematologic abnormalities including hemolytic anemia and thrombocytopenia 1

Practical Dosing Example

For a 20 kg child (age 5 years) with moderate renal impairment (CrCl 35 mL/min):

• Standard dose would be: 150 mg/kg/day = 3000 mg/day = 1000 mg every 8 hours
• Adjusted dose: Give loading dose of 1000 mg, then 750-1000 mg every 8-12 hours 2
• Administer each dose as IV infusion over 30-60 minutes 1

Common Pitfalls to Avoid

• Do not use standard pediatric dosing without adjustment in renal impairment—this significantly increases seizure and nephrotoxicity risk 1, 2
• Do not rely on serum creatinine alone if measured by Jaffé method, as cefoxitin causes false elevation 1
• Do not forget the loading dose in renal impairment—therapeutic levels are needed immediately 2
• Drug level monitoring is not currently available in the UK or US, so clinical response and toxicity monitoring are essential 1