High-dose cefepime therapy is recommended for febrile neutropenia. Safety issues have been raised in a recent meta-analysis reporting an increased risk of mortality during cefepime therapy. Cefepime-related neurological toxicity has been associated with overdosing due to severe renal dysfunction. This study aimed to investigate the association between cefepime plasma concentrations and neurological toxicity in febrile neutropenic patients. Cefepime trough concentrations (by high-performance liquid chromatography) were retrospectively analyzed for 30 adult febrile neutropenic patients receiving the recommended high-dose regimen (6 g/day for a glomerular filtration rate [GFR] of >50 ml/min). The dose adjustment to renal function was evaluated by the ratio of the cefepime daily dose per 100 ml/min of glomerular filtration. The association between cefepime plasma concentrations and neurological toxicity was assessed on the basis of consistent neurological symptoms and/or signs (by NCI criteria). The median cefepime concentration was 8.7 mg/liter (range, 2.1 to 38 mg/liter) at a median of 4 days (range, 2 to 15 days) after the start of therapy. Neurological toxicity (altered mental status, hallucinations, or myoclonia) was attributed to cefepime in 6/30 (20%) patients (median GFR, 45 ml/min; range, 41 to 65 ml/min) receiving a median dose of 13.2 g/day per 100 ml/min GFR (range, 9.2 to 14.3 g/day per 100 ml/min GFR). Cefepime discontinuation resulted in complete neurological recovery for five patients and improvement for one patient. A multivariate logistic regression model confirmed high cefepime concentrations as an independent predictor of neurological toxicity, with a 50% probability threshold at >22 mg/liter (P ‫؍‬ 0.05). High cefepime plasma concentrations are associated with neurological toxicity in febrile neutropenic patients with mild renal dysfunction. Careful adherence to normalized dosing per 100 ml/min GFR is crucial. Monitoring of plasma concentrations may contribute to preventing neurological toxicity of high-dose therapy for this life-threatening condition.Cefepime, an extended-spectrum cephalosporin, is recommended for the empirical therapy of febrile neutropenia (11). The time during which the antibiotic plasma concentration is higher than the MIC for the causative pathogen is crucial for efficacy under this life-threatening condition (16). High-dose cefepime therapy (6 g/day for a glomerular filtration rate [GFR] of Ͼ50 ml/min) is recommended to achieve coverage of the most frequent bacterial pathogens in febrile neutropenia, including Pseudomonas aeruginosa (9, 26). Despite success rates of up to 60 to 80%, similar to those of other broadspectrum beta-lactams, cefepime therapy has recently been found to be associated with higher mortality rates (29). These findings indirectly suggest that the excess mortality might be due to toxicity. In vitro and in vivo studies have attributed the proconvulsive effect of cephalosporins to the drug-induced suppression of inhibitory neurotransmission via a concen...

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