What is the recommended dose of Cefepime for a patient with impaired renal function (GFR of 42)?

Cefepime Dosing for GFR 42 mL/min

For a patient with GFR 42 mL/min (creatinine clearance 30-60 mL/min range), administer cefepime 500 mg IV every 24 hours for mild-moderate infections, or 1 g IV every 24 hours for severe infections, or 2 g IV every 24 hours for life-threatening infections including febrile neutropenia or severe pneumonia. 1

FDA-Approved Dosing Algorithm

The FDA label provides explicit dosing based on creatinine clearance 1:

• For CrCl 30-60 mL/min (which encompasses your patient's GFR of 42):

  • Standard infections: 500 mg IV every 24 hours 1
  • Moderate-severe infections: 1 g IV every 24 hours 1
  • Severe infections (pneumonia, complicated UTI): 2 g IV every 24 hours 1
  • Life-threatening infections (febrile neutropenia, severe Pseudomonas): 2 g IV every 12 hours 1

• Administer over 30 minutes IV infusion 1

Critical Safety Considerations

Neurotoxicity risk is significantly elevated in renal impairment, particularly when doses are not properly adjusted. 2, 3, 4

Neurotoxicity Warning Signs

• Most cases occur between days 2-5 of therapy 2
• Altered mental status is the most common presentation (92% of cases) 2
• Other manifestations include hallucinations, myoclonus, seizures, and encephalopathy 2, 4
• Patients aged ≥65 years account for 52% of neurotoxicity cases 2

High-Risk Scenarios

Patients with severe renal dysfunction receiving higher doses (≥4 g in first 48 hours) have significantly increased neurotoxicity risk 3:

• In severe renal dysfunction subgroup: 16% developed neurotoxicity with higher doses vs 0% with lower doses 3
• Plasma concentrations ≥22 mg/L carry 50% probability of neurotoxicity 4
• Even mild renal impairment (GFR 41-65 mL/min) can result in 20% neurotoxicity rate with standard high-dose regimens 4

Dosing Selection Strategy

Choose the dose based on infection severity and site 1:

Mild-Moderate Infections

• Uncomplicated UTI or pyelonephritis: 500 mg IV every 24 hours 1
• Uncomplicated skin/soft tissue infections: Consider alternative agent or 1 g IV every 24 hours 1

Severe Infections

• Severe UTI/pyelonephritis: 2 g IV every 24 hours 1
• Moderate-severe pneumonia (non-Pseudomonas): 1 g IV every 24 hours 1
• Pneumonia with Pseudomonas: 2 g IV every 12 hours 1
• Complicated intra-abdominal infections (with metronidazole): 2 g IV every 24 hours 1

Life-Threatening Infections

• Febrile neutropenia: 2 g IV every 12 hours 1
• Severe Pseudomonas infections: 2 g IV every 12 hours 1

Monitoring Requirements

Monitor closely for neurotoxicity development, especially in the first 5 days 2:

• Daily neurological assessment for altered mental status, confusion, myoclonus 2, 4
• If neurotoxicity develops, discontinue cefepime immediately—complete recovery typically occurs within 1-5 days 2
• Consider therapeutic drug monitoring if available, targeting trough concentrations <22 mg/L 4
• Reassess renal function every 2-3 days as clearance may fluctuate in critically ill patients 5

Common Pitfalls to Avoid

Do not use standard dosing (2 g every 8 hours) without renal adjustment—this is the most common error leading to neurotoxicity 2, 4:

• 52% of neurotoxicity cases occurred in patients who never received appropriate renal dose adjustment 2
• Standard high-dose regimens (6 g/day) in patients with GFR 41-65 mL/min resulted in 20% neurotoxicity rate 4

Do not assume stable renal function—critically ill patients may have dynamic changes in clearance requiring dose re-evaluation 5

Do not continue cefepime if neurological symptoms develop—immediate discontinuation results in rapid resolution (85% within 1-5 days) 2