The pharmacokinetic profile of a new generation of parenteral cephalosporin

Cystatin C Outperforms Creatinine in Predicting Cefepime Clearance in Pediatric Stem Cell Transplant Recipients

Pediatric hematopoietic stem cell transplant (HSCT) patients are at risk of developing both sepsis and altered kidney function. Cefepime is used for empiric coverage post-HSCT and requires dose adjustment based on kidney function. Since cefepime's antimicrobial efficacy is determined by the time free concentrations exceed bacterial minimum inhibitory concentration (MIC), it is important to assess kidney function accurately to ensure adequate concentrations. Serum creatinine (SCr) is routinely used to estimate glomerular filtration rate (eGFR) but varies with muscle mass, which can be significantly lower in HSCT patients, making SCr an inaccurate kidney function biomarker. Cystatin C (CysC) eGFR is independent of muscle mass, though steroid use increases CysC. Objectives of this study were to describe how eGFR impacts cefepime pharmacokinetic/pharmacodynamic (PK/PD) target attainment in pediatric HSCT patients, to investigate which method of estimating GFR (SCr, CysC, combined) best predicts cefepime clearance, and to explore additional predictors of cefepime clearance. Patients admitted to the pediatric HSCT unit who received ≥2 cefepime doses were prospectively enrolled. We measured total cefepime peak/trough concentrations between the second and fourth cefepime doses and measured SCr and CysC if not already obtained clinically within 24h of cefepime samples. eGFRs were calculated with Chronic Kidney Disease in Children U25 equations. Bayesian estimates of cefepime clearance were determined with a pediatric cefepime PK model and PK software MwPharm++. Simple linear regression was used to compare cefepime clearance normalized to body surface area (BSA) to BSA-normalized SCr-, CysC-, and SCr-/CysC-eGFRs, while multiple linear regression was used to account for additional predictors of cefepime clearance. For target attainment, we assessed the percentage of time free cefepime concentrations exceeded 1x MIC (%fT>1x MIC) and 4x MIC (%fT>4x MIC) using a susceptibility breakpoint of 8 mg/L for Pseudomonas aeruginosa. We enrolled 53 patients (ages 1 to 30 years, median 8.9 years). SCr- and CysC-eGFRs were lower in patients who attained 100% fT>1xMIC compared to those who did not attain this target: 115 versus 156 mL/min/1.73m2 (p = .01) for SCr-eGFR and 73.5 versus 107 mL/min/1.73m2 (p < .001) for CysC-eGFR. SCr-eGFR was weakly positively correlated with cefepime clearance (adjusted [a]r2= 0.14), while CysC-eGFR and SCr-/CysC-eGFR had stronger positive correlations (ar2 = 0.30 CysC, ar2 = 0.28 combo. There was a weak, significant linear association between increasing CysC-eGFR and decreased %fT>1xMIC (ar2 = 0.32) and %fT>4xMIC (ar2 = 0.14). No patients with a CysC-eGFR >120 mL/min/1.73 m2 achieved 100% fT>1xMIC or 50% fT>4x MIC. In multiple regression models, underlying diagnosis of hemoglobinopathy (in all models) and being pretransplant (in SCr and combined models) were associated with increased cefepime clearance, while concomitant use of calcineurin inhibitors was associated with decreased cefepime clearance in all models. Overall, the combo-eGFR model with timing pretransplant, hemoglobinopathy, and use of calcineurin inhibitors had the best performance (ar2 = 0.63). CysC-based eGFRs (CysC alone and combined) predicted cefepime clearance better than SCr-eGFR, even after considering steroid use. Increasing CysC eGFR correlated with decreased probability of PD target attainment, raising concerns for underdosing at high eGFRs. CysC should be included when estimating kidney function to provide adequate dosing of cefepime in pediatric HSCT patients.

Tissue Penetration of Antimicrobials in Intensive Care Unit Patients: A Systematic Review—Part I

The challenging severity of some infections, especially in critically ill patients, makes the diffusion of antimicrobial drugs within tissues one of the cornerstones of chemotherapy. The knowledge of how antibacterial agents penetrate tissues may come from different sources: preclinical studies in animal models, phase I–III clinical trials and post-registration studies. However, the particular physiopathology of critically ill patients may significantly alter drug pharmacokinetics. Indeed, changes in interstitial volumes (the third space) and/or in glomerular filtration ratio may influence the achievement of bactericidal concentrations in peripheral compartments, while inflammation can alter the systemic distribution of some drugs. On the contrary, other antibacterial agents may reach high and effective concentrations thanks to the increased tissue accumulation of macrophages and neutrophils. Therefore, the present review explores the tissue distribution of beta-lactams and other antimicrobials acting on the cell wall and cytoplasmic membrane of bacteria in critically ill patients. A systematic search of articles was performed according to PRISMA guidelines, and tissue/plasma penetration ratios were collected. Results showed a highly variable passage of drugs within tissues, while large interindividual variability may represent a hurdle which must be overcome to achieve therapeutic concentrations in some compartments. To solve that issue, off-label dosing regimens could represent an effective solution in particular conditions.

Cefepime use: A need for antimicrobial stewardship

OBJECTIVES

Unlike other 3GCs, Cefepime is a cephalosporin that has, in animal model studies, shown a low risk of selecting resistant mutants. It also enables carbapenems to be saved in treatment of Pseudomonasaeruginosa and the CESP group (Citrobacter, Enterobacter, Serratia and Providencia, as well as the genus Klebsiellaaerogenes, Morganella and Hafnia), consequently producing cephalosporinase. We aimed to determine whether its prescription in a French teaching hospital met criteria for proper use.

PATIENTS AND METHODS

We conducted a retrospective study of proper cefepime use between March 1st, 2018 and February 28th, 2019, to assess indication, antimicrobial stewardship, dosing schedule, microbiological documentation, reevaluation, and treatment duration. Prescriptions were then compared to local guidelines established from international literature.

RESULTS

Out of 142 cefepime prescriptions, 97.2% were prescribed as validated according to indication. The duration of the documented treatments matched the guidelines for 56.5% of patients, dosage was adapted to the indication for 77.4% and to kidney function for 97.2%. Bacteriological documentation was performed in all cases and an antibiogram was generated in 99.2% of cases. The treatment was reassessed between 48 and 72h and between the 7th and 10th day for 44.2% and 60.9% of the prescriptions respectively. The antimicrobial stewardship team managed half of the prescriptions. Only 13.4% of prescriptions met all criteria for proper use.

CONCLUSION

Notwithstanding a highly sizable majority of validated indications, a very small proportion of cefepime prescriptions met all the criteria for proper use. In the context of increased cefepime consumption, which is favored by its increased place in the latest recommendations published in 2019, proper use of cefepime prescriptions needs to be more effectively promoted.

Potential implications of DMET ontogeny on the disposition of commonly prescribed drugs in neonatal and pediatric intensive care units

Introduction: Pediatric patients, especially neonates and infants, are more susceptible to adverse drug events as compared to adults. In particular, immature small molecule drug metabolism and excretion can result in higher incidences of pediatric toxicity than adults if the pediatric dose is not adjusted.Area covered: We reviewed the top 29 small molecule drugs prescribed in neonatal and pediatric intensive care units and compiled the mechanisms of their metabolism and excretion. The ontogeny of Phase I and II drug metabolizing enzymes and transporters (DMETs), particularly relevant to these drugs, are summarized. The potential effects of DMET ontogeny on the metabolism and excretion of the top pediatric drugs were predicted. The current regulatory requirements and recommendations regarding safe and effective use of drugs in children are discussed. A few representative examples of the use of ontogeny-informed physiologically based pharmacokinetic (PBPK) models are highlighted.Expert opinion: Empirical prediction of pediatric drug dosing based on body weight or body-surface area from the adult parameters can be inaccurate because DMETs are not mature in children and the age-dependent maturation of these proteins is different. Ontogeny-informed-PBPK modeling provides a better alternative to predict the pharmacokinetics of drugs in children.

Cefepime-Induced Encephalopathy

Cefepime, a fourth-generation cephalosporin, remains an essential antibiotic targeting a broad spectrum of Gram-positive and Gram-negative organisms. However, it also remains an important, yet often unrecognized, cause of encephalopathy. We are here to discuss a case of a 74-year-old male with a common bile duct low-grade adenoma who presented to the hospital for lethargy. He was placed on intravenous cefepime for a Pseudomonas-infected hepatobiliary abscess. Approximately five days later, the patient’s spouse reported acutely worsening cognitive changes. The cefepime level was significantly elevated at 160 µg/mL. Although not completely understood, cefepime is felt to antagonize gamma-aminobutyric acid A (GABA-A) receptors and possibly inhibit GABA release. This risk is accentuated in patients with underlying renal dysfunction and increased inflammation across the blood-brain barrier. Clinical manifestations include an impaired level of consciousness, delirium, myoclonus, and seizures. The treatment of choice is the cessation of the antibiotic, which resolves the neurotoxicity within approximately 48 hours. It is important to recognize cefepime as a potential culprit of acute-onset encephalopathy in the appropriate clinical setting, and the cessation of therapy would lead to a complete resolution of its associated neurotoxicity.

Cefepime-induced encephalopathy in patient without renal failure

This case report describes neurotoxicity in an older patient on cefepime 2 g twice a day. The 81-year-old male patient developed non-convulsive status epilepticus during cefepime treatment with 1 g twice a day. There was recovery 30 days after discontinuation of cefepime.

Evaluating outcomes of alternative dosing strategies for cefepime: a qualitative systematic review

OBJECTIVE

To perform a qualitative systematic review of the evidence comparing traditional with prolonged intermittent or continuous infusions of cefepime based on clinical and pharmacodynamic outcomes.

DATA SOURCES

PubMed (1946 to October 2014), EMBASE (1980 to October 2014), CENTRAL, Cochrane Database of Systematic Reviews, Web of Science, and International Pharmaceutical Abstracts (1970 to October 2014) were searched using the terms cefepime, pharmacokinetics, pharmacodynamics, drug administration, intravenous infusions, intravenous drug administration, continuous infusion, extended infusion, and intermittent therapy. Reference lists from relevant materials were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Articles evaluating administration regimens of cefepime, one of which included the traditional, manufacturer-recommended 0.5-hour infusion and the other a prolonged or continuous infusion were included. Prespecified clinical outcomes of interest included all-cause mortality, length of hospital stay, clinical cure, and adverse events. The primary pharmacodynamic outcome was percentage time of unbound drug concentration remaining above the minimum inhibitory concentration.

DATA SYNTHESIS

In all, 18 studies were included; 6 studies assessed clinical outcomes, and 12 assessed pharmacodynamic outcomes. Prolonged or continuous infusions of cefepime achieved the pharmacodynamic targets more often than traditional infusions. The association of improved clinical outcomes with prolonged or continuous infusions is unclear. All-cause mortality was significantly decreased with the use of a prolonged cefepime infusion in a retrospective study. Two prospective, randomized studies demonstrated no statistically significant difference in mortality between prolonged and intermittent infusions.

CONCLUSIONS

The available literature on prolonged and continuous infusions of cefepime demonstrated an improved achievement of pharmacodynamic targets; however, the effect on clinical outcomes is inconclusive. Well-designed prospective studies are required to determine optimal dosing and administration strategies.

Cefepime-induced encephalopathy in patients with haematological malignancies: clinical features and risk factors

BACKGROUND

Cefepime is an antibiotic that is widely used in patients with haematological malignancies (HM). Although its use has been reported to be associated with encephalopathy, only case reports or small case series have been reported so far.

PATIENTS AND METHODS

We conducted a retrospective cohort study of 243 patients with HM treated with cefepime at our hospital between August 2011 and May 2013. We also investigated the clinical features of patients with cefepime-induced encephalopathy (CIE).

RESULTS

Among 243 HM patients treated with cefepime, 10 were diagnosed with CIE, indicating a cumulative incidence of approximately 4.1%. The median creatinine level on commencement of treatment was 2.13 mg/dl (range 0.60-19.85) and the median initial dose of cefepime was 4.0 g/day (range 1.0-6.0). The median time between commencement of treatment and symptoms was 4.0 days (range 2-5). The most common clinical manifestations were decreased level of consciousness and myoclonus. Symptoms resolved fully in all patients. Univariate analyses showed that impaired renal function (creatinine clearance (CLCr) < 30 ml/min, acute renal failure, and chronic dialysis) was significantly associated with the development of CIE (univariate p < 0.0001, p = 0.020, and p = 0.0025, respectively). Receiver operating characteristic (ROC) analysis demonstrated that the threshold levels of creatinine, CLCr, and estimated glomerular filtration rate for CIE were 1.22 mg/dl, 22.96 ml/min, and 43.9 ml/min/1.73 m(2), respectively.

CONCLUSIONS

This study indicated that the development of CIE is associated with severely impaired renal function in patients with HM.

Cefepime

Cefepime (Maxipime), Maxcef, Cepimax, Cepimex, Axepim, a parenteral fourth-generation cephalosporin, is active against many organisms causative in pneumonia. Cefepime has in vitro activity against Gram-positive organisms including Staphylococcus aureus and penicillin-sensitive, -intermediate and -resistant Streptococcus pneumoniae similar to that of cefotaxime and ceftriaxone. Cefepime also has good activity against Gram-negative organisms, including Pseudomonas aeruginosa, similar to that of ceftazidime. Importantly, cefepime is stable against many of the common plasmid- and chromosome-mediated beta-lactamases and is a poor inducer of AmpC beta-lactamases. As a result, it retains activity against Enterobacteriaceae that are resistant to third-generation cephalosporins, such as derepressed mutants of Enterobacter spp. Cefepime may be hydrolyzed by the extended-spectrum beta-lactamases produced by some members of the Enterobacteriaceae, but to a lesser extent than the third-generation cephalosporins. Monotherapy with cefepime 1 or 2g, usually administered intravenously twice daily, was as effective for clinical and bacteriological response as ceftazidime, ceftriaxone or cefotaxime monotherapy (1 or 2g two or three times daily) in a number of randomized, clinical trials in hospitalized adult, or less commonly, pediatric, patients with generally moderate to severe community-acquired or nosocomial pneumonia. More limited data indicated that monotherapy with cefepime 2g three times daily was also as effective in treating patients with nosocomial pneumonia as imipenem/cilostatin 0.5g four times daily, and when combined with amikacin, cefepime was as effective as ceftazidime plus amikacin. Patients with pneumonia who failed to respond to previous antibacterial therapy with penicillins or other cephalosporins responded to treatment with cefepime. Cefepime is generally well tolerated, with a tolerability profile similar to those of other parenteral cephalosporins. In clinical trials, the majority of adverse events experienced by cefepime recipients were mild to moderate and reversible. The most common adverse events with a causal relationship to cefepime reported in clinical trials included rash and diarrhea. Other, less common, adverse events included pruritus, urticaria, nausea, vomiting oral candidiasis, colitis, headache, fever, erythema and vaginitis.

CONCLUSION

Cefepime is an established and generally well tolerated parenteral drug with a broad spectrum of antibacterial activity which, when administered twice daily, provides coverage of most of the pathogens that may be causative in pneumonia. In randomized clinical trials in hospitalized patients with generally moderate to severe community-acquired or nosocomial pneumonia, cefepime monotherapy exhibited good clinical and bacteriological efficacy. Cefepime may become a preferred antibacterial agent for infections caused by Enterobacter spp. With prudent use in order to prevent the emergence of resistant organisms, cefepime will continue to be a suitable option for the empiric treatment of pneumonia.

Cefepime neurotoxicity in patients with renal insufficiency

Cefepime is a fourth-generation cephalosporin that is active against both gram-positive and gram-negative organisms. It is administered parenterally for the treatment of severe infections. Approximately 85% of the drug is excreted unchanged by the kidneys. Neurotoxicity in patients with renal failure who are treated with cefepime has been reported sporadically. We report on two senile patients with renal impairment who developed neurotoxicity including lethal outcome after treatment with cefepime.

Cephalosporin-induced neurotoxicity: clinical manifestations, potential pathogenic mechanisms, and the role of electroencephalographic monitoring

OBJECTIVE

To review the clinical manifestations of cephalosporin-induced neurotoxicity, underlying potential mechanisms, role of electroencephalographic (EEG) monitoring, and management of neurotoxicity.

DATA SOURCES

A PubMed search (1970-May 2008) was conducted using search terms such as cephalosporins, neurotoxicity, seizures, and status epilepticus. The search was not limited to the English language and yielded approximately 187 articles.

STUDY SELECTION AND DATA EXTRACTION

Several case reports and case series were included to outline the salient clinical features of cephalosporin neurotoxicity. Laboratory studies investigating the potential mechanisms were also included. Reports outlining the EEG features of cephalosporin neurotoxicity were included and the role of continuous EEG monitoring was extracted. Finally, management strategies of such neurotoxicity are discussed.

DATA SYNTHESIS

Cephalosporin-induced neurotoxicity may manifest in a variety of clinical presentations, ranging from simple encephalopathy or mental status changes to myoclonus, asterixis, seizures, nonconvulsive status epilepticus, as well as coma. Patients who are elderly, those with renal insufficiency, and those with prior neurologic disease may be particularly prone to the neurotoxic effects. The main mechanism of neurotoxicity appears to involve gamma-aminobutyric acid A receptor inhibition, although other mechanisms may be possible. Cephalosporin neurotoxicity may be associated with a variety of EEG manifestations. Treatment mainly involves withdrawal of the offending drug, in addition to hemodialysis in patients with renal failure, and use of benzodiazepines or other anticonvulsants in patients who develop frank status epilepticus. Neurotoxicity can be prevented in high-risk cases with dosage adjustments and monitoring of serum concentrations.

CONCLUSIONS

Knowledge and awareness of the neurotoxic clinical manifestations, EEG findings, and underlying mechanisms are essential for clinicians in identifying and treating this potentially lethal but reversible complication of cephalosporin therapy. Further studies are needed to determine the most appropriate treatment paradigms for patients who develop status epilepticus as a result of cephalosporins.

The safety of cefepime in the treatment of infection

BACKGROUND

Cefepime is a fourth-generation cephalosporin usually reserved for treating severe nosocomial pneumonia, as well as empirical treatment of febrile neutropenia, uncomplicated and complicated urinary tract infections, uncomplicated skin and skin structure infections, and complicated intra-abdominal infections.

OBJECTIVE

Since reports of neurotoxic effects and of an all-cause mortality higher with cefepime than with comparators have created some concerns regarding its safety, this paper reviews data available in the PubMed database up to December 2007 on cefepime safety.

METHODS

Literature data from PubMed obtained by combining cefepime and safety, or cefepime and clinical trials, were examined.

RESULTS/CONCLUSIONS

Caution in the use of cefepime should be adopted until new evidence on cefepime safety is available.

Once-Daily Cefepime Versus Ceftriaxone for Nursing Home–Acquired Pneumonia

OBJECTIVES

To compare once-daily intramuscular cefepime with ceftriaxone controls.

DESIGN

Double-blind study.

SETTING

Six skilled nursing facilities.

PARTICIPANTS

Residents aged 60 and older with nursing home-acquired pneumonia.

INTERVENTION

Cultures were obtained, and patients were randomized to cefepime or ceftriaxone 1 g intramuscularly every 24 hours.

MEASUREMENTS

Clinical success: cure or improvement. Cure was defined as complete resolution of all symptoms and signs of pneumonia or a return to the patient's baseline state. Improvement was defined as clear improvement but incomplete resolution of all pretherapy symptoms or signs or incomplete return to the patient's usual baseline status. Safety and pharmacoeconomics were also assessed.

RESULTS

Sixty-nine patients were randomized; 61 were evaluable: (32 to cefepime, 29 ceftriaxone). Patients were predominately female (76%). They had a mean age+/-standard deviation of 85+/-6, with a mean 5.8+/-1.9 comorbidities; they had age-appropriate renal dysfunction, with a mean estimated creatinine clearance of 35+/-7 mL/min. Clinical success occurred in 78% of cefepime- and 66% of ceftriaxone-treated patients (P=.39). Fifty-seven patients (93%) were switched to oral antibiotics after 3 days. Antibiotic-related adverse events occurred in 5% of patients. Seven patients (11.5%) were hospitalized. The overall mortality rate was 8%. Mean antibiotic costs were 117+/-40 dollars for cefepime- and 215+/-68 dollars for ceftriaxone-treated patients (P<.001). Cost-effectiveness analysis of total costs showed that cefepime would cost 597 dollars and ceftriaxone 1,709 dollars per expected successfully treated patient. One- and two-way sensitivity analyses using a generic price for ceftriaxone and improving its comparative efficacy revealed that the results were robust.

CONCLUSIONS

Once-daily cefepime was a cost-effective alternative to ceftriaxone for the treatment of elderly nursing home residents who developed pneumonia and did not require hospitalization.

Nonconvulsive status epilepticus during cephalosporin therapy

Cephalosporins may induce nonconvulsive status epilepticus (NCSE), a potentially reversible condition. Despite the wide use of these antibiotics, there are only few reported cases, because this condition is probably underestimated. We report two new cases of NCSE occurring during treatment with cefepime and ceftazidime, and emphasize the utility of emergent electroencephalogram in patients with an acute altered state of consciousness while receiving treatment with cephalosporins, particularly when there is evidence of impaired renal function.

Pharmacokinetic population study to describe cefepime lung concentrations

Pharmacokinetic parameters of cefepime in 2 g plasma and lung tissue bid over 3 days to achieve the steady-state was studied in 16 patients (15 male, one female) subjected to lung surgery for bronchial epithelioma. The aims of this study were firstly to quantify cefepime lung diffusion with cefepime lung concentrations in comparison with cefepime serum concentrations, and secondly to estimate population pharmacokinetic parameters of cefepime in lung tissue using NONMEM. The mean characteristics of patients were: age, 60 years (range, 51-69 years), weight, 73 kg (range, 62-87 kg) and creatinine clearance, 77 ml/min (range, 62-92 ml/min). Both serum sample (two per patient) and lung sample (one per patient) cefepime concentrations were analysed by HPLC with UV detection. Five groups were made according to the time of sampling after the last cefepime intravenous infusion at the fifth infusion: 0.5 h (n=2), 2 h (n=5), 4 h (n=3), 8 h (n=3) and 12 h (n=3). The cefepime concentration ratio between lung and serum was calculated for each group and statistical analysis show no significant difference between groups. The mean concentration ratio between lung and serum was 101% (range, 70-130%). To explain this observation a two-compartment pharmacokinetic model with a population approach was used to describe pharmacokinetic parameters of cefepime both in lung and in serum. Serum was assimilated at the central compartment and lung was the peripheral compartment. NONMEM was used to estimate the mean and the variance of the pharmacokinetic parameters. Central volume of distribution (V(d)), steady-state volume of distribution (V(ss)), central clearance (CL) and transfer constants (K(cp)) from serum to lung and (K(pc)) from lung to serum were estimated. Central elimination half-life t(1/2Kbeta)was extrapolated from elimination constant beta. Results were: V(d)= 15.62 +/- 2.56 l, V(ss)= 17.58 +/- 2.58 l, CL = 3.65 +/- 1.25 l/h, beta = 0.234 h(-1), t(1/2beta)= 2.96 hours, K(cp)= 12.25 +/- 8.56 h(-1)and K(pc)= 0.242 +/- 0.085 h(-1). The results show that cefepime diffusion in lung occurs quickly without lagtime and in similar concentrations to that in serum.

Rapid high-performance liquid chromatographic determination of cefepime in human plasma

A simple, rapid and reproducible high-performance liquid chromatographic method for the quantitative determination of cefepime in human plasma was developed. Ceftazidime was used as internal standard. Chromatography was performed on a reversed-phase encapped column (Hypersil BDS C18). The samples, after protein precipitation, were eluted with a mobile phase of acetonitrile-acetate buffer, pH 4 (2.8:97.2, v/v). The detection wavelength was 254 nm. The limit of quantitation of cefepime was 0.5 microgram/mL and only 0.5 mL of plasma sample was required for the determination. The average cefepime recoveries over a concentration range of 0.5-500 micrograms/mL ranged from 98 to 104%. Precision and accuracy did not exceed 5%.