Cefepime neurotoxicity: thresholds and risk factors. A retrospective cohort study

Antimicrobial safety considerations in critically ill patients: part II: focused on anti-microbial toxicities

INTRODUCTION

Antibiotic prescription is a challenging issue in critical care settings. Different pharmacokinetic and pharmacodynamic properties, polypharmacy, drug interactions, and high incidence of multidrug-resistant microorganisms in this population can influence the selection, safety, and efficacy of prescribed antibiotics.

AREAS COVERED

In the current article we searched PubMed, Scopus and Google Scholar for neurotoxicities, hematologic toxicity and fluid stewardship in intensive care units.

EXPERT OPINION

Critically ill patients who receive antimicrobial agents should be monitored for neurological, hematologic toxicities especially seizure, thrombocytopenia, and clostridioides infections. Other toxicities including QTc prolongation, electrolyte disturbances, liver enzyme elevation, and infusion-related reactions were being considered. Other changes, including fluid overload, hypoalbuminemia, augmented renal clearance, increased cardiac outputs in septic shock, and acute kidney injury, may influence treatment efficiency and patient outcome.

Implementation of a β-lactam therapeutic drug monitoring program: Experience from a large academic medical center

DISCLAIMER

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

To describe the implementation and operationalization of a β-lactam (BL) therapeutic drug monitoring(TDM) program at a large academic center.

SUMMARY

BLs are the most used class of antibiotics. Suboptimal antibiotic exposure is a significant concern in hospitalized patients, particularly in those with altered pharmacokinetics. BL-TDM provides clinicians the opportunity to optimize drug concentrations to ensure maximal therapeutic efficacy while minimizing toxicity. However, BL-TDM has not been widely adopted due to the lack of access to assays. The University of Florida Shands Hospital developed a BL-TDM program in 2015. This is a consultative service primarily run by pharmacists and is conducted in all patient care areas. An analysis was performed on the first BL-TDM encounter for 1,438 patients. BL-TDM was most frequently performed for cefepime (61%, n = 882), piperacillin (15%, n = 218), and meropenem (11%, n = 151). BL-TDM was performed a median of 3 days (interquartile range, 1-5 days) from BL initiation. Among patients with available minimum inhibitory concentration (MIC) values and trough concentrations, the pharmacokinetic/pharmacodynamic (PK/PD) target of 100% fT>MIC was attained in 308 patients (88%). BL-TDM resulted in a dosage adjustment in 25% (n = 361) of patients.

CONCLUSION

Implementation of a BL-TDM program requires the concerted efforts of physicians, pharmacists, nursing staff, phlebotomists, and personnel in the analytical laboratory. Standard antibiotic dosing failed to achieve optimal PK/PD targets in all patients; utilizing BL-TDM, dose adjustments were made in 1 of every 4 patients.

Approach to Cefepime-Induced Neurotoxicity in the Setting of Chronic Kidney Disease: A Case Report and Review of Literature

Cefepime-induced neurotoxicity is well-known, but an under-recognized event that can present with a myriad of neurological findings ranging from myoclonus to seizures to comatose state. It is more prevalent in patients with impaired renal clearance as it is mainly cleared by the kidneys. We present a case of a 52-year-old female who was managed in the intensive care unit with severe encephalopathy following empiric antibiotic therapy with cefepime. Although we encountered some unforeseen difficulties executing our initial plan of renal replacement therapy, our patient was successfully treated with fluids and intravenous diuresis with furosemide and was ultimately discharged home with full recovery.

Cefepime-Induced Neurotoxicity in the Setting of Acute Kidney Injury: A Case Series and Discussion of Preventive Measures

Neurotoxicity is a well-described adverse effect of cefepime. Clinical presentation includes mild neurological deficits, aphasia, impairment of consciousness, and even nonconvulsive status epilepticus. Impaired kidney function is considered the most important risk factor for cefepime-induced neurotoxicity (CIN) and frequently occurs during the course of critical diseases with concomitant acute kidney injury (AKI). Physicians should be aware of situations with increased risk of AKI and the preventive actions required to reduce the risk of CIN. We present three patients with AKI who were treated with cefepime for healthcare-associated infections. Subsequently, two patients developed CIN demonstrating very high cefepime levels in plasma. In the third patient, CIN was likely prevented as the increased risk of neurotoxicity was noted and cefepime treatment was ceased immediately. Diagnosis of CIN might be challenging due to various causes of encephalopathy, in particular in the setting of severely ill patients. Electroencephalogram may assist in establishing the diagnosis, in particular when cefepime therapeutic drug monitoring is not available. As CIN is potentially reversible, it is an important differential diagnosis to consider especially in patients with impaired renal function or being susceptible to AKI. Preventive measures of CIN include therapeutic drug monitoring, consideration of a therapeutic alternative, awareness regarding a potential overestimation of the glomerular filtration rate, and electronic health record alerts about risk constellations for potential overdosing.

Cefepime Induced Neurotoxicity Following A Regimen Dose-Adjusted for Renal Function: Case Report and Review of the Literature

Introduction: Cefepime induced neurotoxicity (CIN) is commonly associated with renal dysfunction, however CIN can occur in patients with normal renal function or renally dose-adjusted regimens. Few reports of this kind have obtained cefepime concentrations to assist in diagnosis. Patient Case: A 42-year old female with a complex past medical history was transferred to our facility with chief complaint of worsening shock and respiratory failure, and the patient was also noted to be hypernatremic, experiencing diabetic ketoacidosis (DKA), and acute kidney injury (AKI). Her DKA resolved and hypernatremia and AKI began to improve. As a result, cefepime was dose-adjusted for renal function estimated by the Cockcroft-Gault (CG) equation. Her hospital course was complicated by persistent altered mental status (AMS), preventing extubation. Cefepime was discontinued due to concern for CIN, and a concentration was obtained 13-hours after the last dose which was elevated at 49 µg/mL. Two days following cefepime discontinuation, the patient's mental status improved allowing for successful extubation. The patient remained stable and was discharged to an acute care floor and then ultimately back to home. Conclusion: CIN should be part of a wider differential diagnosis for patients experiencing encephalopathy, and inaccurate renal function estimation may be a risk factor for developing CIN. Furthermore, therapeutic drug monitoring (TDM) may serve as an important clinical tool in diagnosing and managing CIN.

Real-Life Use of Ceftolozane/Tazobactam for the Treatment of Bloodstream Infection Due to Pseudomonas aeruginosa in Neutropenic Hematologic Patients: a Matched Control Study (ZENITH Study)

We sought to assess the characteristics and outcomes of neutropenic hematologic patients with Pseudomonas aeruginosa (PA) bloodstream infection (BSI) treated with ceftolozane-tazobactam (C/T). We conducted a multicenter, international, matched-cohort study of PA BSI episodes in neutropenic hematologic patients who received C/T. Controls were patients with PA BSI treated with other antibiotics. Risk factors for overall 7-day and 30-day case fatality rates were analyzed. We compared 44 cases with 88 controls. Overall, 91% of episodes were caused by multidrug-resistant (MDR) strains. An endogenous source was the most frequent BSI origin (35.6%), followed by pneumonia (25.8%). There were no significant differences in patient characteristics between groups. C/T was given empirically in 11 patients and as definitive therapy in 41 patients. Treatment with C/T was associated with less need for mechanical ventilation (13.6% versus 33.3%; P = 0.021) and reduced 7-day (6.8% versus 34.1%; P = 0.001) and 30-day (22.7% versus 48.9%; P = 0.005) mortality. In the multivariate analysis, pneumonia, profound neutropenia, and persistent BSI were independent risk factors for 30-day mortality, whereas lower mortality was found among patients treated with C/T (adjusted OR [aOR] of 0.19; confidence interval [CI] 95% of 0.07 to 0.55; P = 0.002). Therapy with C/T was associated with less need for mechanical ventilation and reduced 7-day and 30-day case fatality rates compared to alternative agents in neutropenic hematologic patients with PA BSI.

IMPORTANCE Ceftolozane-tazobactam (C/T) has been shown to be a safe and effective alternative for the treatment of difficult to treat infections due to Pseudomonas aeruginosa (PA) in the general nonimmunocompromised population. However, the experience of this agent in immunosuppressed neutropenic patients is very limited. Our study is unique because it is focused on extremely immunosuppressed hematological patients with neutropenia and bloodstream infection (BSI) due to PA (mainly multidrug resistant [MDR]), a scenario which is often associated with very high mortality rates. In our study, we found that the use of C/T for the treatment of MDR PA BSI in hematological neutropenic patients was significantly associated with improved outcomes, and, in addition, it was found to be an independent risk factor associated with increased survival. To date, this is the largest series involving neutropenic hematologic patients with PA BSI treated with C/T.

Evaluation of the safety of cefepime prolonged infusions in pediatric patients with cystic fibrosis

OBJECTIVE

Pediatric cystic fibrosis (CF) patients possess unique pharmacokinetics and may benefit from prolonged beta-lactam infusions to optimize pharmacodynamics. This study compared adverse drug event (ADE) rates with cefepime prolonged (PI) and standard infusions (SI).

METHODS

This retrospective study included pediatric patients treated with cefepime for CF exacerbations between 2009 and 2019. One encounter per patient was analyzed with prioritization of SI encounters given sample size limitations. Baseline lab abnormalities, seizure disorders, and bleeding were exclusion criteria. The primary outcome was a composite safety endpoint (acute kidney injury [AKI], hepatotoxicity, hematologic toxicity, neurotoxicity, and hypersensitivity).

RESULTS

Of 188 patients, 135 received PI and 53 received SI. Baseline characteristics were similar between groups. More PI patients used CF transmembrane conductance regulator (CFTR) modulators (25% vs. 0%, p < 0.01) or had antibiotic allergies (62% vs. 38%, p = 0.02). Difference in rates of composite safety endpoint was not statistically significant between PI and SI (21 [15.6%] vs. 6 [11.3%] p = 0.46) nor was incidence of AKI (16 [11.8%] vs. 6 [11.3%], p = 0.92). Other ADEs were rarely observed. Length of stay (12.2 vs. 10.1 days, p = 0.06), change in discharge ppFEV1 from admission (13 vs. 12, p = 0.91) or from baseline (-4 vs. -6.5, p = 0.33), and time to next exacerbation (249.7 vs. 192.5 days, p = 0.93) were similar.

CONCLUSIONS

No difference in risk of ADEs including AKI was seen with cefepime PI in pediatric CF patients. Clinical outcomes were not significantly different between groups, but sample size may have limited comparison. PI cefepime may be considered in pediatric CF patients to optimize pharmacodynamics.

A Review of Extended and Continuous Infusion Beta-Lactams in Pediatric Patients

Intravenous beta-lactam antibiotics are the most prescribed antibiotic class in US hospitalized patients of all ages; therefore, optimizing their dosing is crucial. Bactericidal killing is best predicted by the time in which beta-lactam drug concentrations are maintained above the organism's minimum inhibitory concentration (MIC), rather than achievement of a high peak concentration. As such, administration of beta-lactam antibiotics via extended or continuous infusions over a minimum of 3 hours, rather than standard infusions over approximately 30 minutes, has been associated with improved achievement of pharmacodynamic targets and improved clinical outcomes in adult medical literature. This review summarizes the pediatric medical literature. Applicable studies include pharmacodynamic models, case series, retrospective analyses, and prospective studies on the use of extended infusion and continuous infusion penicillins, cephalosporins, carbapenems, and monobactams in neonates, infants, children, and adolescents. Specialized patient populations with unique pharmacokinetics and high-risk infections (neonates, critically ill, febrile neutropenia, cystic fibrosis) are also reviewed. While more studies are needed to confirm prospective clinical outcomes, the current body of evidence suggests extended and continuous infusions of beta-lactam antibiotics are well tolerated in children and improve achievement of pharmacokineticpharmacodynamic targets with similar or superior clinical outcomes, particularly in infections associated with high MICs.

Population Pharmacokinetic-Pharmacodynamic Target Attainment Analysis of Flomoxef in the Serum and Liver Tissue of Patients Undergoing Hepatic Resection

The purpose of this study was to investigate the population pharmacokinetics of prophylactic flomoxef based on serum and liver tissue concentrations and to demonstrate a pharmacodynamic target concentration in the serum and liver tissue exceeding the MIC in order to design an effective dosing regimen. Serum samples (n = 210) and liver tissue samples (n = 29) from 43 individuals were analyzed using a nonlinear mixed-effects model. The pharmacodynamics index target value was regarded as the probability of maintaining flomoxef serum trough and liver tissue concentrations exceeding the MIC₉₀ values, 0.5 mg/L and 1.0 mg/L, for Escherichia coli and methicillin-susceptible Staphylococcus aureus, respectively. The final population pharmacokinetic model was a two-compartment model with linear elimination. Creatinine clearance (CL_CR) was identified as a significant covariate influencing total clearance when CL_CR was less than 60 mL/min. The probability of achieving concentrations in the serum and liver tissue exceeding the MIC₉₀ for E. coli or methicillin-susceptible S. aureus for a 1 g bolus dose was above 90% at 2 h after the initial dose. Our findings suggest that population pharmacokinetic parameters are helpful for evaluating flomoxef pharmacokinetics and determining intraoperative flomoxef redosing intervals.

Cefepime Dosing Requirements in Elderly Patients Attended in the Emergency Rooms

Objective

This study aimed to assess the probability of reaching an adequate pharmacokinetic/pharmacodynamic (pK/pD) index for different cefepime dosages in frail patients with bacteremia treated in the emergency room.

Methods

Simulation study based on Gram-negative bacterial strains that cause bacteremia. The probability of reaching a time above the minimum inhibitory concentration (MIC) at 50% and 100% dosing intervals (fT > 50 and fT > 80% MIC) was assessed for two different renal clearance intervals.

Results

One hundred twenty nine strains were collected, the predominant species being Escherichia coli (n = 83 [64.3%]). In patients with a ClCr of 30 mL/min, an fT > 50% MIC was reached in more than 90% of the simulations. However, a dose of at least 1 g every 12 h must be administered to reach an fT > 80% MIC. In patients with a ClCr of 30–60 mL/min, the probability of reaching an fT > 50% MIC was higher than 90% with doses of 1 g every 8 h or more, but this value was not reached in > 90% simulations for any of the doses tested in this study.

Conclusions

Standard cefepime dosing can reach an adequate PK/PD index in frail patients. Nevertheless, a high dose or extended infusion is necessary to reach an fT > 80% MIC in patients with a ClCr > 60 mL/min.

An optimal extended-infusion dosing of cefepime and ceftazidime in critically ill patients with continuous renal replacement therapy

PURPOSE

This study aimed to determine optimal extended-infusion dosing regimens for cefepime and ceftazidime in critically ill patients receiving continuous renal replacement therapy using Monte Carlo Simulations (MCS).

MATERIALS AND METHODS

Pharmacokinetic models were built using published pharmacokinetic/demographic data to predict drug disposition in 5000 virtual critically ill patients receiving continuous venovenous hemofiltration (CVVH) with the standard (20-30 mL/kg/h) and a higher (40 mL/kg/h) effluent rates. MCS was performed to assess the probability of target attainment (PTA) of four cefepime and ceftazidime doses administered over 4-h with the target of ≥60% fT > 4×MIC. The lowest dose attaining PTA ≥90% during the first 48-h was considered optimal. Additionally, risk of drug toxicity was assessed at 48-h using suggested neurotoxicity thresholds.

RESULTS

Cefepime 2 g loading dose (LD), then extended-infusion of 2 g q8hr was optimal in CVVH at 20 mL/kg/h and the same ceftazidime dose was optimal in CVVH at 20-30 mL/kg/h. Higher cefepime and ceftazidime doses were required to be optimal at higher effluent rates. This optimal dose particularly for cefepime likely increases neurotoxicity risk in most virtual patients with all CVVH settings.

CONCLUSIONS

Cefepime and ceftazidime 2 g LD, followed by extended-infusion 2 g q8hr may be optimal in CVVH with standard effluent rates.

Cefepime-Induced Neurotoxicity in a 74-Year-Old Woman

Cefepime is a fourth-generation cephalosporin with anti-pseudomonal coverage. It has been known to cause neurotoxicity, especially in critically ill patients and those with renal impairment. This neurotoxicity is poorly characterized and under-recognized. We present a case of cefepime-induced neurotoxicity in a 74-year-old woman being treated for cellulitis and osteomyelitis. Symptoms were gradual in onset and included confusion, verbal perseveration, and myoclonus. EEG findings included generalized periodic discharges (GPD) and generalized rhythmic delta activity with admixed sharps (GRDA + S). Symptoms resolved one to two days after the cessation of cefepime and anti-epileptic therapy with lorazepam, topiramate, and levetiracetam. We follow this with a discussion of available literature and recommend regular therapeutic drug monitoring in the future.

Therapeutic Drug Monitoring of Antibiotics: Defining the Therapeutic Range

PURPOSE

In the present narrative review, the authors aimed to discuss the relationship between the pharmacokinetic/pharmacodynamic (PK/PD) of antibiotics and clinical response (including efficacy and toxicity). In addition, this review describes how this relationship can be applied to define the therapeutic range of a particular antibiotic (or antibiotic class) for therapeutic drug monitoring (TDM).

METHODS

Relevant clinical studies that examined the relationship between PK/PD of antibiotics and clinical response (efficacy and response) were reviewed. The review (performed for studies published in English up to September 2021) assessed only commonly used antibiotics (or antibiotic classes), including aminoglycosides, beta-lactam antibiotics, daptomycin, fluoroquinolones, glycopeptides (teicoplanin and vancomycin), and linezolid. The best currently available evidence was used to define the therapeutic range for these antibiotics.

RESULTS

The therapeutic range associated with maximal clinical efficacy and minimal toxicity is available for commonly used antibiotics, and these values can be implemented when TDM for antibiotics is performed. Additional data are needed to clarify the relationship between PK/PD indices and the development of antibiotic resistance.

CONCLUSIONS

TDM should only be regarded as a means to achieve the main goal of providing safe and effective antibiotic therapy for all patients. The next critical step is to define exposures that can prevent the development of antibiotic resistance and include these exposures as therapeutic drug monitoring targets.

OUP accepted manuscript

Objectives

To describe the therapeutic drug monitoring (TDM) of cefepime in non-critically ill adults and compare four different ways of dosing: conventional table-based; empirically adjusted following TDM; individualized based on a population pharmacokinetic (PopPK) model without TDM; and TDM-adjusted with a Bayesian approach integrating TDM and PopPK.

Methods

We conducted a retrospective study in a tertiary centre to examine the current practice of TDM and to evaluate the potential for improvement by PopPK-based software individualization. The prediction of trough concentrations and the total daily doses (TDD) prescribed according to each approach were compared by calculating the mean logarithmic bias and the root mean squared error, complemented by linear regression and variance analysis.

Results

Among 168 trough concentrations in 119 patients (median: 12 mg/L), 38.6% of measurements exceeded 15 mg/L, the reported threshold for neurotoxicity. Nine patients developed neurotoxicity. The prediction performance of PopPK alone for trough concentrations was moderate, but clearly improved after integration of TDM. Accordingly, TDD were significantly lower for a priori PopPK-based dosage (mean: 2907 mg/24 h) compared with actual table-based dosage (4625 mg/24 h, P < 0.001). They were also lower for a posteriori dosage based on PopPK and TDM (3377 mg/24 h) compared with actual dosage after empirical TDM (4233 mg/24 h, P < 0.001), as model-based adjustment privileged more frequent administrations.

Conclusions

Our observations support routine TDM of cefepime to prevent overdosing and subsequent toxicity in the non-critically ill. Software-based individualization seems promising to optimize the benefits of TDM, but has little potential to replace it.

Cefepime precision dosing tool: From Standard to Precise Dose Using Nonparametric Population Pharmacokinetics

Cefepime is the second most common cephalosporin used in U.S. hospitals. We aim to develop and validate cefepime population pharmacokinetic (PK) model and integrate into precision dosing tool for implementation. Two datasets (680 patients) were used to build cefepime PK model in Pmetrics, and three datasets (34 patients) were used for the validation. A separate application dataset (115 patients) was used for the implementation and validation of a precision dosing tool. The model support points and covariates were used to generate the optimal initial dose (OID). Cefepime PK was described by a two-compartment model including weight and creatinine clearance (CrCl) as covariates. The median rate of elimination was 0.30 hr^-1 (adults) and 0.96 hr^-1 (pediatrics), central volume of distribution 13.85 L, and rate of transfer from the central to the peripheral compartments 1.22 hr^-1 and from the peripheral to the central compartments 1.38 hr^-1. After integration in BestDose, the observed vs. predicted cefepime concentration fit using the application dataset was excellent (R²>0.98) and the median difference between observed and what BestDose predicted in a second occasion was 4%. For OID, cefepime 0.5-1g 4-hour infusion q8-24hr with CrCl<70 mL/min was needed to achieve a target range of free trough:MIC 1-4 at MIC 8 mg/L, while continuous infusion was needed for higher CrCl and weight values. In conclusion, we developed and validated a cefepime model for clinical application. The model was integrated in a precision dosing tool for implementation and the median concentration prediction bias was 4%. OID algorithm was provided.

Dose optimisation of antibiotics used for meningitis

PURPOSE OF REVIEW

Central nervous system (CNS) infections such as ventriculitis and meningitis are associated with significant morbidity and mortality. In part, this may be due to increased difficulties in achieving a therapeutic antibiotic concentration at the site of infection due to both the pharmacokinetic (PK) changes observed during critical illness and the reduced antibiotic penetration through the blood brain barrier. This paper reviews the pharmacodynamics (PD) and CNS PKs of antibiotics used for Gram-negative bacterial CNS infections to provide clinicians with practical dosing advice.

RECENT FINDINGS

Recent PK studies have shown that currently used intravenous antibiotic dosing regimens may not achieve a therapeutic exposure within the CNS, even for reportedly 'susceptible' bacteria per the current clinical meningitis breakpoints. Limited data exist for new β-lactam antibiotic/β-lactamase inhibitor combinations, which may be required for multidrug resistant infections. Intraventricular antibiotic administration, although not a new concept, has further evidence demonstrating improved patient outcomes compared with intravenous therapy alone, despite the ongoing paucity of PK studies guiding dosing recommendations.

SUMMARY

Clinicians should obtain the bacterial minimum inhibitory concentration when treating patients with CNS Gram-negative bacterial infections and consider the underlying PK/PD principles when prescribing antibiotics. Therapeutic drug monitoring, where available, should be considered to guide dosing. Intraventricular therapy should also be considered for patients with ventricular drains to optimise clinical outcomes.

Cefepime-Induced Encephalopathy in a High-Risk Patient With Renal Insufficiency and Cirrhosis

Cefepime is a fourth-generation, cephalosporin antibiotic commonly used as a first-line empirical treatment in a wide range of bacterial infections. It is predominantly excreted renally; therefore, a reduction in kidney function allows for the accumulation of cefepime to potentially toxic levels. Here we present a case of cefepime-induced encephalopathy (CIE) in a 67 years old male patient with advanced-stage renal insufficiency and cirrhosis who was admitted to our hospital for altered mental status (AMS). The patient was initially treated for hepatic encephalopathy (HE) given an elevated ammonia level (105 µg/dL), which had significantly improved. He was also placed on intravenous (IV) cefepime for Pseudomonas bacteremia. Four days later, the patient became drowsy and confused. A detailed workup for secondary causes of AMS was performed however no significant acute abnormalities were detected. The ammonia level remained within the normal range. There was no acute intracranial pathology reported on a head computerized tomography (CT). Furthermore, an electroencephalograph (EEG) was obtained which showed generalized periodic discharge with a tri-phasic wave pattern suggesting non-convulsive status epilepticus (NCSE). CIE was suspected at that point and cefepime administration was stopped. Following cefepime discontinuation, there was a remarkable improvement in the patient’s mental status for several days after cefepime discontinuation that supported the diagnosis of CIE in our patient.

Although the exact pathophysiology is unclear, CIE should be suspected in elderly patients, patients with renal dysfunction, and critical illness. Meanwhile, liver dysfunction can be an additional risk factor for CIE as it increases the permeability of the blood-brain barrier (BBB), altered neurotransmission, and neuro-inflammation.

Prospective assessment of breakthrough infections and neurotoxicity and their association with cefepime trough concentrations in patients with febrile neutropenia

Cefepime is a first-line antibiotic for the treatment of febrile neutropenia (FN) in haematological cancer patients. Therapeutic drug monitoring (TDM) of cefepime is frequently advocated. However, it remains unclear what range of concentrations should be targeted for maximal efficacy and minimal toxicity. Therefore, we examined the relationship between cefepime exposure and clinical efficacy or neurotoxicity in FN patients. This prospective, observational, single-centre study included all adult hospitalised patients presenting with FN at the haematology ward and treated with cefepime from August 2019 until October 2020. Primary outcomes were incidence of breakthrough infection and neurotoxicity and their relationship with free cefepime serum trough concentrations. A total of 76 patients were included, contributing 96 cefepime treatment courses. The median (interquartile range) estimated glomerular filtration rate according to the Chronic Kidney Disease Epidemiology Collaboration equation (eGFR_CKD-EPI) and free cefepime trough concentration were 101 (85-112) mL/min/1.73m² and 8.6 (4.9-16.2) mg/L, respectively. Interpatient and intrapatient variability in cefepime trough concentrations was largely explained by renal function. No cefepime-related breakthrough infections occurred during cefepime treatment. Neurotoxicity, probably induced by cefepime administration, occurred during 6/96 (6.3%) treatment courses. Patients with neurotoxicity showed a significant trend for higher trough concentrations (median 15.4 mg/L vs. 8.6 mg/L; P < 0.001). This study provides real-world clinical data showing that high cefepime dosage is efficacious and safe in FN patients. Routine TDM does not appear to be needed in FN patients with preserved renal function. However, TDM might be reserved for FN patients at high risk of cefepime-induced neurotoxicity or when intended to cover pathogens with a minimum inhibitory concentration >1 mg/L.

Population pharmacokinetics of cefepime in critically ill patients receiving extracorporeal membrane oxygenation (an ASAP ECMO study)

OBJECTIVES

This study aimed to describe the population pharmacokinetics (PK) of cefepime during extracorporeal membrane oxygenation (ECMO) and through dosing simulations, identify a maximally effective and safe dosing strategy.

METHODS

Serial cefepime plasma concentrations were measured in patients on ECMO, and data were analysed using a population PK approach with Pmetrics®. Dosing simulations were used to identify the optimal dosing strategy that achieved target trough concentrations (C_min) of 8-20 mg/L. Six patients were enrolled, of which one was receiving renal replacement therapy. Cefepime was best described in a two-compartment model, with total body weight and creatinine clearance (CrCL) as significant predictors of PK parameters. The mean clearance and central volume of distribution were 2.42 L/h and 15.09 L, respectively.

RESULTS

Based on simulations, patients with CrCL of 120 mL/min receiving 1 g 8-hourly dosing achieved a 40-44% probability of efficacy (C_min > 8 mg/L) and 1-6% toxicity (C_min > 20 mg/L). Patients with CrCL 30 mL/min and 65 mL/min receiving 1 g 12-hourly dosing achieved an 84-92% and 46-53% probability of efficacy and 8-44% and 1-8% probability of toxicity, respectively. Simulations demonstrated a lower probability of efficacy and higher probability of toxicity with decreasing patient weight.

CONCLUSION

This study reported reduced cefepime clearance in patients receiving ECMO, resulting in an increased risk of cefepime toxicity. To avoid drug accumulation, modified dosing regimens should be used in critically ill patients on ECMO. Clinicians should adopt therapeutic drug monitoring when treating less susceptible organisms and in patients with reduced renal clearance on ECMO.

Transcriptome and microbiome analyses of the mechanisms underlying antibiotic-mediated inhibition of larval development of the saprophagous insect Musca domestica (Diptera: Muscidae)

Antibiotics are designed to treat bacterial infections in humans and animals; however, the overuse of various antibiotics and consequent contamination in the environment can have adverse effects on aquatic, soil, and saprophytic organisms. The house fly, an important decomposer in ecosystems, has been used for bioconversion of human and animal waste. Vermireactors have been used to remove antibiotics from waste for pollution control, but the effects of antibiotics on fly larvae are unclear. In the present work, we aimed to reveal the mechanism underlying the effects of antibiotics on larval growth in house flies at the transcriptome and microbiome levels and the relationships between genes and the microbiota. Observation of house flies after antibiotic exposure showed that gentamicin sulfate and levofloxacin hydrochloride inhibited larval development to a greater extent than amoxicillin. Transcriptome analysis revealed that biological pathways related to protein synthesis and the metabolism of fatty acids, pentose, and glucuronate were significantly enriched in flies exposed to gentamicin sulfate and levofloxacin hydrochloride. Crucial genes in these pathways were identified as candidates for future study. Microbiome analysis revealed three key bacteria that were closely correlated with gentamicin sulfate and levofloxacin hydrochloride exposure. The correlation network between the differentially expressed genes and bacteria identified an important microbic effector, Pseudomonas and its associated genes. This work will improve the knowledge about the mechanism underlying the effects of antibiotics on the larval development of house flies in the environment and provide guidance for improving the application of house fly bioconversion.

Assessment of cefepime toxicodynamics: comprehensive examination of pharmacokinetic/pharmacodynamic targets for cefepime-induced neurotoxicity and evaluation of current dosing guidelines

BACKGROUND

Cefepime-induced neurotoxicity (CIN) is an increasingly reported adverse event; however, the toxicity threshold remains unclear. This study was conducted to provide a comprehensive examination of the most appropriate threshold for CIN, and evaluate the ability of current dosing regimens to attain therapeutic targets.

METHODS

Data of the incidence of CIN and cefepime plasma concentrations were collected retrospectively from patients administered cefepime. Population pharmacokinetic modelling was used to determine daily cefepime trough concentration (C_min), maximum serum concentration and area under the concentration-time curve. The ability of each pharmacokinetic parameter to predict CIN was evaluated using receiver operating characteristic (ROC) curves, from which optimal toxicity thresholds were determined. Pharmacokinetic simulation was used to evaluate the ability of cefepime dosing guidelines to meet established efficacy targets, whilst maintaining exposure below the determined CIN threshold.

RESULTS

In total, 102 cefepime courses were evaluated, with CIN reported in 10. ROC analyses showed that all cefepime pharmacokinetic parameters were strongly predictive of CIN. C_min of 49 mg/L was identified as the optimal toxicity target, based on its predictive ability (0.88, 95% confidence interval 0.758-0.999, P<0.001) and ease of clinical use. Assessment of cefepime dosing regimens predicted that only 29% of simulated patients achieve therapeutic targets, with patients with impaired renal function more likely to exhibit subtherapeutic concentrations (89%), and patients with normal renal function likely to have potentially toxic exposure (64%).

CONCLUSIONS

The findings from this study provide evidence that cefepime exposure is highly predictive of CIN, with C_min of 49 mg/L being the most appropriate toxicity threshold. Further research is required to optimize cefepime dosing in the context of this therapeutic target.

Evaluation Of Individualized Cefepime Dosing Strategy Using Population Pharmacokinetics

The use of population pharmacokinetics (PK) to optimize cefepime dosing could be an effective strategy, given the increasing prevalence of resistant gram-negative organisms. The objective of this study is to retrospectively compare dosing using PK approach (intervention) versus traditional dosing (control) for cefepime in patients with hospital-acquired pneumonia (HAP) or ventilator-associated pneumonia (VAP). Adult hospitalized patients with HAP or VAP receiving cefepime for ≥ 72 hours were screened first from August 2018 to January 2019 to be included in the intervention group, then screened during the pre-intervention period from August 2017 to July 2018 for the control group. Clinical improvement on day 7 of cefepime therapy was achieved in 72 % of the patients in the intervention group and 70 % of the patients in the control group (p = 0.8110). However, the clinical cure rate in the intervention group was higher than that of the control group (50 vs. 36.5 %, p = 0.0034). Cefepime dosing using population PK appears to be a novel, effective, and safe dosing strategy for patients with HAP or VAP. This article is protected by copyright. All rights reserved.

Neurotoxicity Despite a Renal Function-Adjusted Cefepime Regimen: A Case Study

An 83-year-old man, presenting decreased renal function (estimated glomerular filtration rate 21 mL/min/1.73 m), was treated for a bone and joint infection (on a trans-metatarsal right foot amputation) caused by Klebsiella Pneumonia sensitive to cefepime. The starting dose (1 g bid) was based on recommendations for patients presenting severe infections. One week after treatment initiation, the patient developed neurotoxicity, exhibiting extremely high plasma cefepime concentrations. Based on TDM, the dose was reduced by 8 times the original dose. This case report highlights the importance of therapeutic drug monitoring for cefepime, especially in patients presenting altered renal functions, as typical recommendations are estimated for standard patients.

Pharmacokinetic/Pharmacodynamic Dosage Individualization of Cefepime in Critically Ill Patients: A Case Study

OBJECTIVE

The authors report on a case of a 59-year-old man hospitalized in the intensive care unit because of severe SARS-COV-2 infection (COVID-19).

BACKGROUND

The patient had several comorbidities, including liver cirrhosis. He developed ventilation-associated bacterial pneumonia for which he was administered cefepime at an initial dose of 2 g/8 hours. Therapeutic drug monitoring was performed, showing overexposure with an initial trough concentration of >60 mg/L.

METHODS

Analysis of pharmacokinetic data and model-based dose adjustment was performed using BestDose software.

RESULTS

The patient had unexpected pharmacokinetic parameter values. Serum creatinine was only moderately increased, whereas measured creatinine clearance based on urine collection showed impaired renal function. Bacterial minimum inhibitory concentration was also considered in the dosing decisions. After dose reduction to 0.5 g/8 hours, the cefepime trough concentration progressively declined and reached the target values by the end of the therapy. A post-hoc analysis provided a different interpretation of drug overexposure.

CONCLUSION

This case report illustrates how physiological, microbiological, and drug concentration data can be used for model-based dosage individualization of cefepime in intensive care unit patients.

Unmasking antibiotic-associated neurological disorders: The underminer in Intensive Care Unit

Psychosis is a common and intractable disorder of hospitalization, especially in patients hospitalized in Intensive Care Unit (ICU). Along with the widely use of multiple antibiotics in community-acquired infection and hospital-acquired infection, the occurrence of antibiotic-associated neurological disorders has become more frequently. However, antibiotic neurotoxicity is often overlooked or misinterpreted. In this review, we summarized the neurological disorders caused by antibacterial agent usage and firstly systematically formulated the pathogenesis of antibiotic-associated neurotoxic reactions. Precautions of the complications are critical in preventing serious clinical outcome as the inducement is curable. Regular neurological physical examination, electroencephalogram (EEG) examination, lumbar puncture and therapeutic drug monitoring closely are essential for early diagnosis and differential diagnosis.

Tolerance and microbiological efficacy of cefepime or piperacillin/tazobactam in combination with vancomycin as empirical antimicrobial therapy of prosthetic joint infection: a propensity-matched cohort study

BACKGROUND

The use of piperacillin/tazobactam with vancomycin as empirical antimicrobial therapy (EAT) for prosthetic joint infection (PJI) has been associated with an increased risk of acute kidney injury (AKI), leading us to propose cefepime as an alternative since 2017 in our reference centre.

OBJECTIVES

To compare microbiological efficacy and tolerance of these two EAT strategies.

METHODS

All adult patients with PJI empirically treated with vancomycin+cefepime (n = 89) were enrolled in a prospective observational study and matched with vancomycin+piperacillin/tazobactam-treated historical controls (n = 89) according to a propensity score including age, baseline renal function and concomitant use of other nephrotoxic agents. The two groups were compared using Kaplan-Meier curve analysis, and non-parametric tests regarding the proportion of efficacious empirical regimen and the incidence of empirical therapy-related adverse events (AE).

RESULTS

Among 146 (82.0%) documented infections, the EAT was considered efficacious in 77 (98.7%) and 65 (98.5%) of the piperacillin/tazobactam- and cefepime-treated patients, respectively (P = 1.000). The rate of AE, particularly AKI, was significantly higher in the vancomycin+piperacillin/tazobactam group [n = 27 (30.3%) for all AE and 23 (25.8%) for AKI] compared with the vancomycin+cefepime [n = 13 (14.6%) and 6 (6.7%)] group (P = 0.019 and <0.001, respectively), leading to premature EAT discontinuation in 20 (22.5%) and 5 (5.6%) patients (P = 0.002). The two groups were not significantly different regarding their comorbidities, and AKI incidence was not related to vancomycin plasma overexposure.

CONCLUSIONS

Based on the susceptibility profile of bacterial isolates from included patients, microbiological efficacy of both strategies was expected to be similar, but vancomycin + cefepime was associated with a significantly lower incidence of AKI.

A retrospective study to determine the cefepime-induced neurotoxicity threshold in hospitalized patients

OBJECTIVES

Cefepime-induced neurotoxicity (CIN) has been demonstrated to be associated with cefepime plasma concentrations; however, the toxicity threshold remains unclear. The primary objective of this study was to identify the cefepime plasma trough concentration at which neurotoxicity occurs. Secondary objectives were to determine the incidence of CIN at a large tertiary institution and to identify patient factors associated with the development of CIN.

METHODS

A retrospective review of all adult patients administered cefepime between October 2017 and May 2018 in a tertiary hospital was conducted to determine total incidence of CIN. A receiver operating characteristic (ROC) curve was constructed to review the sensitivity and specificity of using various cefepime trough plasma concentrations to predict the development of neurotoxicity. Cefepime plasma concentrations were measured using ultra-HPLC. A regression was conducted to identify patient factors associated with CIN.

RESULTS

In total, 206 patients were administered 259 courses of cefepime, with an overall CIN incidence of 6% (16/259 courses). A total of 64 courses had a cefepime trough concentration measured (24.7%). A cefepime trough concentration of 36 mg/L provided the best differentiation between patients who experienced neurotoxicity and those who did not. No other patient covariates were identified to be significantly associated with neurotoxicity occurring.

CONCLUSIONS

A cefepime trough plasma concentration ≥36 mg/L appears to be the most sensitive and specific cut-off to predict CIN occurring. No patient factors were associated with the development of CIN when accounting for cefepime trough plasma concentrations.

Personalized ß-lactam dosing in patients with coronavirus disease 2019 (COVID-19) and pneumonia: A retrospective analysis on pharmacokinetics and pharmacokinetic target attainment

ABSTRACT

Pathophysiological changes are important risk factors for critically ill patients with pneumonia manifesting sub-therapeutic antibiotic exposures during empirical treatment. The effect of coronavirus disease 2019 (COVID-19) on antibiotic dosing requirements is uncertain. We aimed to determine the effect of COVID-19 on ß-lactam pharmacokinetics (PK) and PK target attainment in critically ill patients with a personalized dosing strategy.Retrospective, single-center analysis of COVID-19 ± critically ill patients with pneumonia (community-acquired pneumonia or hospital-acquired pneumonia) who received continuous infusion of a ß-lactam antibiotic with dosing personalized through dosing software and therapeutic drug monitoring. A therapeutic exposure was defined as serum concentration between (css) 4 to 8 times the EUCAST non-species related breakpoint).Data from 58 patients with pneumonia was analyzed. Nineteen patients were tested COVID-19-positive before the start of the antibiotic therapy for community-acquired pneumonia or hospital-acquired pneumonia. Therapeutic exposure was achieved in 71% of COVID-19 patients (68% considering all patients). All patients demonstrated css above the non-species-related breakpoint. Twenty percent exceeded css above the target range (24% of all patients). The median ß-lactam clearance was 49% compared to ß-lactam clearance in a standard patient without a significant difference regarding antibiotic, time of sampling or present COVID-19 infection. Median daily doses were 50% lower compared to standard bolus dosing.COVID-19 did not significantly affect ß-lactam pharmacokinetics in critically ill patients. Personalized ß-lactam dosing strategies were safe in critically ill patients and lead to high PK target attainment with less resources.

Setting the Beta-Lactam Therapeutic Range for Critically Ill Patients: Is There a Floor or Even a Ceiling?

Beta-lactam antibiotics exhibit high interindividual variability in drug concentrations in patients with critical illness which led to an interest in the use of therapeutic drug monitoring to improve effectiveness and safety. To implement therapeutic drug monitoring, it is necessary to define the beta-lactam therapeutic range-in essence, what drug concentration would prompt a clinician to make dose adjustments up or down. This objective of this narrative review was to summarize evidence for the "floor" (for effectiveness) and "ceiling" (for toxicity) for the beta-lactam therapeutic range to be used with individualized therapeutic drug monitoring.

DATA SOURCES

Research articles were sourced from PubMed using search term combinations of "pharmacokinetics," "pharmacodynamics," "toxicity," "neurotoxicity," "therapeutic drug monitoring," "beta-lactam," "cefepime," "meropenem," "piperacillin/tazobactam," "ICU," and "critical illness."

STUDY SELECTION

Articles were selected if they included preclinical, translational, or clinical data on pharmacokinetic and pharmacodynamic thresholds for effectiveness and safety for beta-lactams in critical illness.

DATA SYNTHESIS

Experimental data indicate a beta-lactam concentration above the minimum inhibitory concentration of the organism for greater than or equal to 40-60% of the dosing interval is needed, but clinical data indicate that higher concentrations may be preferrable. In the first 48 hours of critical illness, a free beta-lactam concentration at or above the susceptibility breakpoint of the most likely pathogen for 100% of the dosing interval would be reasonable (typically based on Pseudomonas aeruginosa). After 48 hours, the lowest acceptable concentration could be tailored to 1-2× the observed minimum inhibitory concentration of the organism for 100% of the dosing interval (often a more susceptible organism). Neurotoxicity is the primary dose-dependent adverse effect of beta-lactams, but the evidence remains insufficient to link a specific drug concentration to greater risk.

CONCLUSIONS

As studies advance the understanding of beta-lactam exposure and response in critically ill patients, it is essential to clearly define the acceptable therapeutic range to guide regimen selection and adjustment.

Cefepime Dosing in Neonates: What is the Evidence?

OBJECTIVE

Recommended cefepime dosing strategies in neonates varies in commonly utilized dosing references with regard to dose and frequency. The objective of this review is to summarize and evaluate the available literature describing cefepime dosing in neonatal patients.

STUDY DESIGN

We performed a literature review in MEDLINE using the keyword cefepime. The search was limited to the English language, humans, and patients <2 months of age. We evaluated four pharmacokinetic studies and two studies describing the use of cefepime in clinical practice.

RESULTS

The available studies assessing cefepime serum concentrations in neonatal patients demonstrated maintenance of adequate pharmacokinetic parameters when utilizing a dosing frequency of every 12 hours, specifically for organisms with a minimum inhibitory concentration (MIC) ≤ 8 mg/L. In studies evaluating clinical outcomes of cefepime use in neonates, the most frequent adverse effects reported included seizures and hypophosphatemia. Microbiologic cure was demonstrated with a dosing regimen of 50 mg/kg per dose every 12 hours.

CONCLUSION

Cefepime dosed 30 to 50 mg/kg per dose every 12 hours may be appropriate to achieve a concentration two to four times above an MIC ≤ 8 mg/L for at least 60% of the dosing interval in neonatal patients.

Cefepime Population Pharmacokinetics and Target Attainment in Critically Ill Patients on Continuous Renal Replacement Therapy

Sepsis causes half of acute kidney injuries in the intensive care unit (ICU). ICU patients may need continuous renal replacement therapy (CRRT), which will affect their antimicrobial exposure. We aimed to build a cefepime population pharmacokinetic (PK) model in CRRT ICU patients and perform simulations to assess target attainment. Patients who were ≥18 years old, were admitted to the ICU, and received cefepime 2 g every 8 h as a 4-h infusion while on CRRT were enrolled prospectively. Samples were collected from the predialyzer ports, postdialyzer ports, and effluent fluid at 1, 2, 3, 4, and 8 h after the first dose and at steady state. Age, sex, weight, urine output, and CRRT parameters were recorded. Pmetrics was used for population PK and simulations. The target exposure was 100% of the dosing interval during which the free beta-lactam concentration is above the MIC (fT _>MIC). Ten patients were included; their mean age was 53 years, and mean weight was 119 kg. Seventy percent were males. Cefepime was described by a five-compartment model. The downtime was applied to the CRRT flow rates, which were used to describe the rates of transfer between the compartments. At MICs of ≤8 mg/liter, intermittent infusion of 2 g cefepime every 8 h achieved good target attainment both early in therapy and at steady state. Only extended- and continuous-infusion regimens achieved good target attainment at MICs of 16 mg/liter. In conclusion, 2 g cefepime infused over 30 min followed by extended infusion of 2 g every 8 h achieved good target attainment at MICs of ≤16 mg/liter with different CRRT flow rates and may be considered in resistant bacterial infections.

Towards precision medicine: Therapeutic drug monitoring-guided dosing of vancomycin and β-lactam antibiotics to maximize effectiveness and minimize toxicity

PURPOSE

The goal of this review is to explore the role of antimicrobial therapeutic drug monitoring (TDM), especially in critically ill, obese, and older adults, with a specific focus on β-lactams and vancomycin.

SUMMARY

The continued rise of antimicrobial resistance prompts the need to optimize antimicrobial dosing. The aim of TDM is to individualize antimicrobial dosing to achieve antibiotic exposures associated with improved patient outcomes. Initially, TDM was developed to minimize adverse effects during use of narrow therapeutic index agents. Today, patient and organism complexity are expanding the need for precision dosing through TDM services. Alterations of pharmacokinetics and pharmacodynamics (PK/PD) in the critically ill, obese, and older adult populations, in conjunction with declining organism susceptibility, complicate attainment of therapeutic targets. Over the last decade, antimicrobial TDM has expanded with the emergence of literature supporting β-lactam TDM and a shift from monitoring vancomycin trough concentrations to monitoring of the ratio of area under the concentration (AUC) curve to minimum inhibitory concentration (MIC). PK/PD experts should be at the forefront of implementing precision dosing practices.

CONCLUSION

Precision dosing through TDM is expanding and is especially important in populations with altered PK/PD, including critically ill, obese, and older adults. Due to wide PK/PD variability in these populations, TDM is vital to maximize antimicrobial effectiveness and decrease adverse event rates. However, there is still a need for studies connecting TDM to patient outcomes. Providing patient-specific care through β-lactam TDM and transitioning to vancomycin AUC/MIC monitoring may be challenging, but with experts at the forefront of this initiative, PK-based optimization of antimicrobial therapy can be achieved.

Negative myoclonus as the leading symptom in acute cefepime neurotoxicity

An 86-year-old woman was diagnosed with hospital-acquired pneumonia with Pseudomonas aeruginosa and treated with cefepime adjusted to her renal clearance. After 4 days, she developed acute-onset negative myoclonus without signs of altered mental status. After ruling out an acute intracranial haemorrhagic or ischaemic stroke as well as other metabolic and endocrine causes of negative myoclonus, the antibiotic was switched to piperacillin/tazobactam due to a suspicion of cefepime neurotoxicity. The patient improved within 24 hours and her symptoms fully resolved within 4 days. These observations suggest a link of the negative myoclonus to acute cefepime neurotoxicity, which may occur without or with minimal alteration of mental status, thus extending its spectrum of clinical presentation.

Validation and Application of an HPLC-UV Method for Routine Therapeutic Drug Monitoring of Cefiderocol

Cefiderocol is a new siderophore cephalosporin approved for the treatment of multidrug resistant bacteria including activity against carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa. As cephalosporins are known for their high pharmacokinetic variability in critically ill patients, cefiderocol therapeutic drug monitoring might become a valuable tool. Therefore, we aimed to develop and validate a simple, rapid, cost-effective high performance liquid chromatography (HPLC) method for the quantification of cefiderocol in serum. Samples were treated for protein precipitation followed by chromatographic separation on a reverse phase column (HPLC C-18) with gradient elution of the mobile phase. Cefiderocol was detected via UV absorption and quantification was performed with the internal standard (metronidazole) method. The calibration range showed linearity from 4 to 160 mg/L. The intra and interday precision was less than 10% with a recovery rate of 81%. The method was successfully used for the analysis of subsequent serum samples of critically ill patients and showed good performance in monitoring serum levels and optimizing antibiotic therapy.

Efficacy and Safety of Cystatin C-Guided Renal Dose Adjustment of Cefepime Treatment in Hospitalized Patients with Pneumonia

Cystatin C (CysC) may estimate renal function more accurately than serum creatinine (SCr). The clinical impact of renal dose adjustment of cefepime according to CysC rather than SCr has remained uncertain. We investigated the efficacy and safety of CysC-guided cefepime dosing compared with SCr-guided dosing in hospitalized patients with pneumonia. All adults hospitalized with pneumonia between July 2016 and December 2018 who used cefepime for at least 3 days were enrolled. Mortality, acute kidney injury (AKI), cefepime-induced encephalopathy (CIE), and Clostridium difficile infection were compared between the CysC-guided and SCr-guided groups. One hundred and ninety patients were divided into two groups: 129 and 61 received cefepime based on CysC and SCr, respectively. In-hospital mortality did not significantly differ between the groups (12% versus 31%; hazard ratio (HR) 0.74; 95% confidence interval (CI), 0.31-1.77; p = 0.50). CysC-guided cefepime dosing decreased the risk of AKI (13% versus 61%; HR 0.18; 95% CI, 0.07-0.44; p < 0.001) and CIE (2% versus 11%; HR 0.11; 95% CI, 0.03-0.47; p = 0.003) compared with SCr-guided dosing. There was no significant difference in the risk of Clostridium difficile infection. CysC-guided dosing of cefepime was associated with decreased risk of the cefepime-associated morbidities including AKI and CIE without increasing mortality among the hospitalized patients with pneumonia.

Population Pharmacokinetics and Target Attainment of Cefepime in Critically Ill Patients and Guidance for Initial Dosing

Cefepime is commonly used in the intensive care unit (ICU) to treat bacterial infections. The time during which the free cefepime concentration is above the MIC (fT_>MIC) should be optimized to increase the efficacy of the regimen. We aim to optimize the exposure of cefepime in ICU patients by using population pharmacokinetic (PK) modeling and simulations. Two data sets were included in this study. The first was a prospective study of pediatric patients who received cefepime at 50 mg/kg of body weight and had extensive PK sampling. The second study comprised retrospective data for adult ICU patients admitted to UF Health Shands Hospital who received cefepime and had their cefepime concentrations measured. The population PK model was developed, and simulations were performed, using Pmetrics. The target exposures were 100% fT_>MIC and 100% fT_>4×MIC The studies included a total of 266 patients, and the mean ages were 3.9 years in the pediatric group and 55 years in adult group. More than half of the patients were males. The mean (standard deviation [SD]) creatinine clearance (CrCl) was 125 (93) ml/min. The mean (SD) daily dose for adults was 4.9 (1.6) g. Cefepime was well described by a two-compartment model with weight as a covariate on the volume of distribution and elimination rate constant (k _el), and CrCl and age group as covariates on k _el At a MIC of 8 mg/liter, a cefepime loading dose of 4 g as an extended infusion followed by a 6-g continuous infusion was needed for good target attainment. In conclusion, prolonged or continuous infusions will be needed to achieve optimal cefepime exposure for ICU patients. Given the observed variability, therapeutic drug monitoring can help individualize therapy.

Cefepime therapeutic drug monitoring: Evaluation of agreement between peripheral and central venous blood sampling

BACKGROUND

Therapeutic drug monitoring for cefepime is increasingly being performed because of the potential relation between exposure and neurotoxicity. An in vitro pilot study suggested significant carryover of cefepime from central venous catheters when blood sampling is carried out via the same catheter used for administration of cefepime. Therefore, the aim of this study was to evaluate carryover of cefepime in a real-life clinical setting.

METHODS

A prospective single-center study was conducted at the hematology department of the University Hospitals Leuven. Patients treated with cefepime, and having a central venous catheter, were included. Cefepime trough samples were taken simultaneously via the central venous catheter and peripheral venepuncture.

RESULTS

Twenty-four patients were included in this study, resulting in 28, 11 and 5 paired samples for tunnelled catheters, implantable port catheters and peripherally inserted central catheters, respectively. No statistically nor clinically significant difference was found between cefepime concentrations measured in centrally versus peripherally obtained blood samples, overall and for all three types of central venous catheters separately. Of note, four paired samples showed a difference larger than 10%, with lower central concentrations probably reflecting a dilution error.

CONCLUSION

There was no significant carryover of cefepime from long-term central venous catheters. Cefepime samples can be drawn reliably via the central venous catheter, after flushing and discarding the first blood sample. Although, flushing and discard volumes should be standardized to avoid potential dilution errors.

Cefepime-Induced Seizures: The Overlooked Outpatient Adverse Reaction

Cefepime is a 4th generation cephalosporin often used for its ability to cover gram-positives, gram negatives, anaerobic bacteria, and, most importantly, pseudomonas. Prior to initiation of cefepime, the medication is dosed based on the renal function to avoid a multitude of its toxicity profiles, including encephalopathy, aphasia, myoclonus, seizures, and nonconvulsive status epilepticus. These risks are increased in the presence of renal impairment. We present a case of a 65-year-old woman who had presented to the emergency department (ED) two weeks after initiation of outpatient IV cefepime therapy with concerns of altered mentation and decreased oral intake. In the ED, the patient was noted to have a creatinine: 5.77 (baseline of 0.76) and urea: 94. During evaluation by the ED provider, the patient was noted to have transient slurring of speech, speech arrest, and tonic-clonic movements on the right. CT of the head, followed by CT angiography of the head and neck, demonstrated no acute intracranial pathology. Spot EEG revealed generalized slowing with unclear left-sided epileptiform discharges. There was a concern for complex partial seizures. Neurology and nephrology were consulted. The patient was given 1 g of levetiracetam, and emergent dialysis was performed. After dialysis, no other epileptiform activity was noted with the improvement of her encephalopathy. The patient returned to her baseline mentation. Here we emphasize the importance of recognizing cefepime’s toxicity profile while triaging patients. In the rare event of toxicity, immediate treatment is discontinuing the offending agent and initiation of emergent hemodialysis.

The management of anti-infective agents in intensive care units: the potential role of a 'fast' pharmacology

INTRODUCTION

Patients in intensive care units (ICU) are often developing severe infections in which are associated with significant mortality rates. A number of novel technologies for the rapid microbiological diagnosis of these infections have been developed, introducing the era of 'fast microbiology.' Treatment of bacterial and fungal infections in ICU is however complicated by alterations in the pharmacokinetics of antimicrobial agents.

AREAS COVERED

We review novel pharmacologic tools that can be used to optimize anti-infective therapies and patient management in ICU. A MEDLINE Pubmed search for articles published from January 1995 to 2019 was completed matching the terms pharmacokinetics and pharmacology with antimicrobial agents and ICU or critically ill patients. Moreover, additional studies were identified from the reference list of retrieved articles.

EXPERT OPINION

Several tools are in development for the full automation of the analytical methods used for the quantification of antimicrobial concentrations within a few hours after sample collection. Ad hoc software with adaptive feedback is also available for appropriate dose adjustments based on both individual patient covariate data and therapeutic drug monitoring (TDM) data when available. The application of these technological improvements in the clinical practice should open the way to a 'fast pharmacology' at the bedside.

Effect of Cefepime on Neurotoxicity Development in Critically Ill Adults With Renal Dysfunction

BACKGROUND

Pharmacodynamic and pathophysiologic changes in critically ill adults receiving cefepime may increase the risk of adverse events.

RESEARCH QUESTION

What is the impact of cefepime exposure on neurotoxicity development in critically ill adults with renal dysfunction?

STUDY DESIGN AND METHODS

Critically ill adults with creatinine clearance < 60 mL/min who received cefepime for ≥ 48 hours between January 1, 2014 and July 31, 2018 were evaluated for cefepime-associated neurotoxicity (CAN) development. Higher- and lower-dose cefepime exposure groups stratified by moderate (≥ 8 g vs < 8 g in first 48 hours) or severe (≥ 4 g vs < 4 g in first 48 hours) renal dysfunction were compared. Between-group comparisons were performed using Fisher exact tests. CAN-free survival was evaluated using Kaplan-Meier curves and log-rank tests.

RESULTS

Cefepime total dose in the first 48 hours was greater in the higher-dose cefepime group (3.7 ± 1.6 g vs 7.7 ± 2.2 g; P < .001). Cefepime-associated neurotoxicity occurred infrequently in both lower- (n = 108) and higher-dose (n = 92) cefepime groups (4% vs 10%, OR 2.82, 95% CI, 0.84-9.48, P = .093). The frequencies of cefepime-associated neurotoxicity were similar between lower- and higher-dose cefepime groups when moderate renal dysfunction subgroups were compared (5% vs 7%, OR 1.42, 95% CI, 0.34-5.92, P = .72) and numerically greater in the higher-dose cefepime group in the severe renal dysfunction subgroup (0 vs 16%, P = .064). Times to cefepime-associated neurotoxicity development and resolution were similar between lower- and higher-dose groups. Durations of CAN-free survival were similar between lower- and higher-dose groups. Most patients who developed cefepime-associated neurotoxicity displayed altered mental status (n = 12, 92%).

INTERPRETATION

Cefepime-associated neurotoxicity is an uncommon occurrence in critically ill adults. Patients with severe renal dysfunction receiving higher-dose cefepime may be at greater risk of cefepime-associated neurotoxicity, although this requires additional investigation.

Pharmacokinetics and Pharmacodynamics of Extended-Infusion Cefepime in Critically Ill Patients Receiving Continuous Renal Replacement Therapy: A Prospective, Open-Label Study

STUDY OBJECTIVE

To evaluate extended-infusion (EI) cefepime pharmacokinetics (PK) and pharmacodynamic target attainment in critically ill patients receiving continuous venovenous hemofiltration (CVVH) or continuous venovenous hemodialysis (CVVHD).

DESIGN

Prospective, open-label, PK study.

SETTING

Intensive care units at a large, academic, tertiary-care medical center.

PATIENTS

Ten critically ill adults who were receiving cefepime 2 g intravenously every 8 hours as a 4-hour infusion while receiving CVVH (eight patients) or CVVHD (two patients).

INTERVENTION

Two sets of five serum cefepime concentrations were collected for each patient to assess pharmacokinetics before and during presumed steady state. Concurrent serum and CRRT effluent samples were collected at hours 1, 2, 3, 4, and 8 after the first cefepime dose and after either the fourth, fifth, or sixth (steady-state) cefepime doses.

MEASUREMENTS AND MAIN RESULTS

Reversed-phase high-performance liquid chromatography was used to determine free cefepime concentrations. PK analyses included CRRT clearance, half-life, and sieving coefficient or saturation coefficient. Cefepime peak (4 hrs) concentrations, trough (8 hrs) concentrations (C_min ), and minimum inhibitory concentration breakpoint of 8 µg/ml for the pathogen (MIC₈ ) were used to evaluate attainment of pharmacodynamic targets: 100% of the dosing interval that free drug remains above MIC₈ (100% fT > MIC₈ ), 100% fT > 4 × MIC₈ (optimal), percentage of time fT > 4 × MIC₈ (%fT > 4 × MIC₈ ) at steady state, and ratio of C_min to MIC₈ (fC_min /MIC₈ ). Total CRRT effluent flow rate was a mean ± SD of 30.1 ± 5.4 ml/kg/hr, CRRT clearance was 39.6 ± 9.9 ml/min, and half-life was 5.3 ± 1.7 hours. Sieving coefficient or saturation coefficient were 0.83 ± 0.13 and 0.69 ± 0.22, respectively. First and steady-state dose C_min were 23.4 ± 10.1 µg/ml and 45.2 ± 14.6 µg/ml, respectively. All patients achieved 100% fT > MIC₈ on first and steady-state doses. First and steady-state dose 100% fT > 4 × MIC₈ were achieved in 22% (2/9 patients) and 87.5% (7/8 patients) of patients, respectively. The mean %fT > 4 × MIC₈ at steady state was 97.5%. The fC_min /MIC₈ was 2.92 ± 1.26 for the first dose and 5.65 ± 1.83 at steady state.

CONCLUSION

Extended-infusion cefepime dosing in critically ill patients receiving CRRT successfully attained 100% fT > MIC₈ in all patients and an appropriate fC_min /MIC₈ for both first and steady-state doses. All but one patient achieved 100% fT > 4 × MIC₈ at steady state. No significant differences were observed in PK properties between first and steady-state doses among or between patients. It may be reasonable to initiate an empiric or definitive regimen of EI cefepime in critically ill patients receiving concurrent CRRT who are at risk for resistant organisms. Further research is needed to identify the optimal dosing regimen of EI cefepime in this patient population.