Can I give 2g of ceftizoxime to a patient with impaired renal function (GFR of 24)?

Ceftizoxime Dosing in Severe Renal Impairment (GFR 24)

You can give ceftizoxime to a patient with a GFR of 24 mL/min, but you must reduce the dose to 250-500 mg every 12 hours for standard infections, or 0.5-1 gram every 12 hours for life-threatening infections. 1

Dose Adjustment Algorithm

The FDA label for ceftizoxime provides explicit dosing guidance based on creatinine clearance, which closely approximates GFR 1:

• For GFR 24 mL/min (falls in the 5-49 mL/min range):
  • Moderate to severe infections: 250-500 mg every 12 hours 1
  • Life-threatening infections: 0.5-1 gram every 12 hours 1
  • Initial loading dose: 500 mg to 1 gram IM or IV is recommended before starting maintenance dosing 1

Your proposed 2 gram dose is NOT appropriate without dose reduction. The maximum recommended dose for life-threatening infections in this degree of renal impairment is 1 gram every 12 hours (2 grams total daily), which is substantially less than a single 2 gram dose 1.

Pharmacokinetic Rationale

The need for dose reduction is driven by significant pharmacokinetic changes in renal impairment 2, 3:

• Elimination half-life increases dramatically: From 1.6-1.9 hours in normal renal function to 16.9 ± 4.5 hours in chronic kidney failure patients 3, 4
• Clearance is reduced proportionally to the degree of renal dysfunction, as ceftizoxime is cleared entirely by glomerular filtration without metabolism 3
• Drug accumulation occurs without dose adjustment, increasing toxicity risk 2, 4

Research demonstrates that appropriately adjusted doses achieve similar minimum plasma concentrations and adequate time above MIC (100% for patient isolates) across all renal function groups, with comparable clinical outcomes 2.

Critical Safety Considerations

Beta-lactam neurotoxicity risk increases in renal impairment, even with dose adjustments 5. Monitor for:

• Confusion or encephalopathy
• Myoclonus
• Seizures 5

Timing with dialysis: If the patient undergoes hemodialysis, no additional supplemental dosing is required after dialysis, but time the dose to be given at the end of dialysis 1. Ceftizoxime is removed by both hemodialysis and peritoneal dialysis 3, 4.

Monitoring Requirements

• Therapeutic drug monitoring should guide further dosing decisions, particularly in severe infections 1
• Assess renal function at steady state using current serum creatinine, as the dosing table assumes stable renal function 1
• Monitor for neurological symptoms throughout treatment, especially given the prolonged half-life in this population 5, 4