Ex Vivo Characterization of Effects of Renal Replacement Therapy Modalities and Settings on Pharmacokinetics of Meropenem and Vaborbactam

Medication patterns and dosing guidance in pediatric patients supported with intermittent hemodialysis or continuous kidney replacement therapy

BACKGROUND

Hemodialysis is a life-saving technology used during periods of acute or chronic kidney failure to remove toxins, and maintain fluid, electrolyte and metabolic balance. While this technology plays an important role for pediatric patients with kidney dysfunction, it can alter the pharmacokinetic behavior of medications placing patients at risk for suboptimal dosing and drug toxicity. The ability to directly translate pharmacokinetic alterations into dosing recommendations has thus far been limited and dosing guidance specific to pediatric hemodialysis patients is rare. Despite differences in dialysis prescription and patient populations, intermittent (iHD) and continuous kidney replacement therapy (CKRT) patients are often pooled together. In order to develop evidence-based dosing guidelines, it is important to first prioritize drugs for study in each modality.

METHODS

Here we aim to identify priority drugs in two hemodialysis modalities, through: 1) Identification of hospitalized, pediatric patients who received CKRT or intermittent hemodialysis (iHD) using a machine learning-based predictive model based on medications; 2) Identification of medication administration patterns in these patient cohorts; and 3) Identification of the most commonly prescribed drugs that lack published dosing guidance.

RESULTS

Notable differences were found in the pattern of medications and drug dosing guidance between iHD and CKRT patients. Antibiotics, diuretics and sedatives were more common in CKRT patients. Out of the 50 most commonly administered medications in the two modalities, only 34% and 28% had dosing guidance present for iHD and CKRT, respectively.

CONCLUSIONS

Our results add to the understanding of the differences between iHD and CKRT patient populations by identifying commonly used medications that lack dosing guidance for each hemodialysis modality, helping to pinpoint priority medications for further study. Overall, this study provides an overview of the current limitations in medication use in this at-risk population, and provides a framework for future studies by identifying commonly used medications in pediatric CKRT and iHD patients.

Meropenem Clearance in a Child With End-stage Renal Disease Undergoing Prolonged Intermittent Renal Replacement Therapy: A Case Report and Literature Review

BACKGROUND

Meropenem is frequently used to treat severe infections in critically ill children. However, pharmacokinetic data on meropenem in children with end-stage renal disease (ESRD) undergoing prolonged intermittent renal replacement therapy (PIRRT) is limited. Our objectives were to evaluate meropenem clearance in a child with ESRD with and without PIRRT, compare the results to previous continuous renal replacement therapy studies in children, toddlers and neonates, and assess whether the currently used dose of meropenem is sufficient.

CASE DESCRIPTION

A 5-year-old girl with an estimated glomerular filtration rate of 12.8 mL/min/1.73 m 2 was diagnosed with pulmonary infection and treated with 300 mg meropenem once a day. PIRRT was performed for 8 hours every 2 days. We used WinNonlin to evaluate meropenem clearance with and without PIRRT.

RESULTS

Our case showed that PIRRT increased the clearance of meropenem from 1.39 (1.3) to 2.42 L/h (2.3 mL/kg/min) and caught up 42.6% of the total clearance. This result is in accordance with previous studies in children but slightly less than seen in toddlers and neonates under continuous renal replacement therapy. The current dose of 300 mg once a day is not sufficient to reach the therapeutic target.

CONCLUSIONS

Predicting meropenem clearance in children with ESRD undergoing PIRRT is difficult as clearance will be affected by renal function, PIRRT settings and other factors. Further studies are needed to explore the individual variability of meropenem clearance and optimize the dosing regimen.

Rationale and evidence for the use of new beta-lactam/beta-lactamase inhibitor combinations and cefiderocol in critically ill patients

BACKGROUND

Healthcare-associated infections involving Gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR) phenotype are associated with impaired patient-centered outcomes and poses daily therapeutic challenges in most of intensive care units worldwide. Over the recent years, four innovative β-lactam/β-lactamase inhibitor (BL/BLI) combinations (ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-relebactam and meropenem-vaborbactam) and a new siderophore cephalosporin (cefiderocol) have been approved for the treatment of certain DTR-GNB infections. The literature addressing their microbiological spectrum, pharmacokinetics, clinical efficacy and safety was exhaustively audited by our group to support the recent guidelines of the French Intensive Care Society on their utilization in critically ill patients. This narrative review summarizes the available evidence and unanswered questions on these issues.

METHODS

A systematic search for English-language publications in PUBMED and the Cochrane Library database from inception to November 15, 2022.

RESULTS

These drugs have demonstrated relevant clinical success rates and a reduced renal risk in most of severe infections for whom polymyxin- and/or aminoglycoside-based regimen were historically used as last-resort strategies-namely, ceftazidime-avibactam for infections due to Klebsiella pneumoniae carbapenemase (KPC)- or OXA-48-like-producing Enterobacterales, meropenem-vaborbactam for KPC-producing Enterobacterales, ceftazidime-avibactam/aztreonam combination or cefiderocol for metallo-β-lactamase (MBL)-producing Enterobacterales, and ceftolozane-tazobactam, ceftazidime-avibactam and imipenem-relebactam for non-MBL-producing DTR Pseudomonas aeruginosa. However, limited clinical evidence exists in critically ill patients. Extended-infusion scheme (except for imipenem-relebactam) may be indicated for DTR-GNB with high minimal inhibitory concentrations and/or in case of augmented renal clearance. The potential benefit of combining these agents with other antimicrobials remains under-investigated, notably for the most severe presentations. Other important knowledge gaps include pharmacokinetic information in particular situations (e.g., pneumonia, other deep-seated infections, and renal replacement therapy), the hazard of treatment-emergent resistance and possible preventive measures, the safety of high-dose regimen, the potential usefulness of rapid molecular diagnostic tools to rationalize their empirical utilization, and optimal treatment durations. Comparative clinical, ecological, and medico-economic data are needed for infections in whom two or more of these agents exhibit in vitro activity against the causative pathogen.

CONCLUSIONS

New BL/BLI combinations and cefiderocol represent long-awaited options for improving the management of DTR-GNB infections. Several research axes must be explored to better define the positioning and appropriate administration scheme of these drugs in critically ill patients.

Jumping into the future: overcoming pharmacokinetic/pharmacodynamic hurdles to optimize the treatment of severe difficult to treat-Gram-negative infections with novel beta-lactams

INTRODUCTION

The choice of best therapeutic strategy for difficult-to-treat resistance (DTR) Gram-negative infections currently represents an unmet clinical need.

AREAS COVERED

This review provides a critical reappraisal of real-world evidence supporting the role of pharmacokinetic/pharmacodynamic (PK/PD) optimization of novel beta-lactams in the management of DTR Gram-negative infections. The aim was to focus on prolonged and/or continuous infusion administration, penetration rates into deep-seated infections, and maximization of PK/PD targets in special renal patient populations. Retrieved findings were applied to the three most critical clinical scenarios of Gram-negative resistance phenotypes (i.e. carbapenem-resistant Enterobacterales; difficult-to-treat resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii).

EXPERT OPINION

Several studies supported the role of PK/PD optimization of beta-lactams in the management of DTR Gram-negative infections for both maximizing clinical efficacy and preventing resistance emergence. Optimizing antimicrobial therapy with novel beta-lactams based on the so called 'antimicrobial therapy puzzle' PK/PD concepts may represent a definitive jump into the future toward a personalized patient management of DTR Gram negative infections. Establishing a dedicated and coordinated multidisciplinary team and implementing a real-time TDM-guided personalized antimicrobial exposure optimization of novel beta-lactams based on expert clinical pharmacological interpretation, could represent crucial cornerstones for the proper management of DTR Gram-negative infections.

UHPLC-MS/MS method for simultaneous quantification of doripenem, meropenem, ciprofloxacin, levofloxacin, pazufloxacin, linezolid, and tedizolid in filtrate during continuous renal replacement therapy

BACKGROUND

Since severe infections frequently cause acute kidney injury (AKI), continuous renal replacement therapy (CRRT) is often initiated for regulation of inflammatory mediators and renal support. Thus, it is necessary to decide the antibiotic dosage considering the CRRT clearance in addition to residual renal function. Some of the hemofilters used in CRRT are known to adsorb antibiotics, and clearance of antibiotics may differ depending on the adsorptive characteristics of hemofilters. Although assay systems for blood and CRRT filtrate concentrations are required, no method for measuring antibiotics concentrations in filtrate has been reported. We developed a UHPLC-MS/MS method for simultaneous quantification of antibiotics commonly used in ICU, comprising carbapenems [doripenem (DRPM) and meropenem (MEPM)], quinolones [ciprofloxacin (CPFX), levofloxacin (LVFX) and pazufloxacin (PZFX)] and anti-MRSA agents [linezolid (LZD), and tedizolid (TZD)] in CRRT filtrate samples.

METHODS

Filtrate samples were pretreated by protein precipitation. The analytes were separated with an ACQUITY UHPLC CSH C18 column under a gradient mobile phase consisting of water and acetonitrile containing 0.1% formic acid and 2 mM ammonium formate.

RESULTS

The method showed good linearity over wide ranges. Within-batch and batch-to-batch accuracy and precision for each drug fulfilled the criteria of the US Food and Drug Administration guidance. The recovery rate was more than 87.20%. Matrix effect ranged from 99.57% to 115.60%. Recovery rate and matrix effect did not differ remarkably between quality control samples at different concentrations.

CONCLUSION

This is the first report of a simultaneous quantification method of multiple antibiotics in filtrate of CRRT circuit.

Pharmacokinetics, Pharmacodynamics, and Dose Optimization of Cefiderocol during Continuous Renal Replacement Therapy

BACKGROUND

The need for continuous renal replacement therapy (CRRT) in critically ill patients with serious infections is associated with clinical failure, emergence of resistance, and excess mortality. These poor outcomes are attributable in large part to subtherapeutic antimicrobial exposure and failure to achieve target pharmacokinetic/pharmacodynamic (PK/PD) thresholds during CRRT. Cefiderocol is a novel siderophore cephalosporin with broad in vitro activity against resistant pathogens and is often used to treat critically ill patients, including those receiving CRRT, despite the lack of data to guide dosing in this population.

OBJECTIVE

The aim of this study was to evaluate the PK and PD of cefiderocol during in vitro and in vivo CRRT and provide optimal dosing recommendations.

METHODS

The PK and dialytic clearance of cefiderocol was evaluated via an established in vitro CRRT model across various modes, filter types, and effluent flow rates. These data were combined with in vivo PK data from nine patients receiving cefiderocol while receiving CRRT from phase III clinical trials. Optimal dosing regimens and their respective probability of target attainment (PTA) were assessed via an established population PK model with Bayesian estimation and 1000-subject Monte Carlo simulations at each effluent flow rate.

RESULTS

The overall mean sieving/saturation coefficient during in vitro CRRT was 0.90 across all modes, filter types, effluent flow rates, and points of replacement fluid dilution tested. Adsorption was negligible at 10.9%. Three-way analysis of variance (ANOVA) and multiple linear regression analyses demonstrated that effluent flow rate is the primary driver of clearance during CRRT and can be used to calculate optimal cefiderocol doses required to match the systemic exposure observed in patients with normal renal function. Bayesian estimation of these effluent flow rate-based optimal doses in nine patients receiving CRRT from the phase III clinical trials of cefiderocol revealed comparable mean (± standard deviation) area under the concentration-time curve values as patients with normal renal function (1709 ± 539 mg·h/L vs. 1494 ± 58.4 mg·h/L; p = 0.26). Monte Carlo simulations confirmed these doses achieved >90% PTA against minimum inhibitory concentrations ≤4 mg/L at effluent flow rates from 0.5 to 5 L/h.

CONCLUSION

The optimal dosing regimens developed from this work have been incorporated into the prescribing information for cefiderocol, making it the first and only antimicrobial with labeled dosing for CRRT. Future clinical studies are warranted to confirm the efficacy and safety of these regimens.

Contribution of diafiltration and adsorption to vancomycin clearance in a continuous hemodiafiltration circuit model in vitro

BACKGROUND

Vancomycin (VCM) is eliminated mainly by diafiltration under continuous hemodiafiltration (CHDF), but the contribution of adsorption to CHDF clearance (CL_CHDF ) of VCM using a polyacrylonitrile and sodium methallyl sulfonate copolymer membrane coated with polyethylenimine (AN69ST) or a polymethylmethacrylate (PMMA) membrane is unknown. This study sought to investigate the contribution of diafiltration and adsorption to the CL_CHDF of VCM using AN69ST and PMMA membranes in vitro.

METHODS

An in vitro CHDF circuit model was developed. The initial concentration of VCM was 50 μg/mL and human serum albumin (HSA) was prepared at a concentration of 0, 2.5, or 5.0 g/dL. The effluent flow rate (Qe) was set at 800, 1500, or 3000 mL/h. The CL_CHDF , diafiltration rate, and adsorption rate of VCM were calculated.

RESULTS

Total CL_CHDF of VCM using the AN69ST membrane increased and decreased with increasing Qe and HSA concentration, respectively. Diafiltration and adsorption rates were 82.1 ± 9.8% and 12.1 ± 6.1% under all conditions, respectively. Total CL_CHDF using the PMMA membrane increased with increasing Qe. Diafiltration and adsorption rates were 89.2 ± 20.4% and 4.6 ± 17.0% under all conditions, respectively. The observed CL_CHDF values significantly correlated with the predicted CL_CHDF , calculated according to a previous study as the product of Qe and the plasma unbound fraction.

CONCLUSIONS

Diafiltration predominantly contributed to CL_CHDF of VCM using AN69ST and PMMA membranes. When diafiltration rather than adsorption mainly contributes to the CL_CHDF of VCM, the CL_CHDF could be predicted from the Qe and HSA concentration, at least in vitro.

Pharmacokinetics of Non-β-Lactam β-Lactamase Inhibitors

The growing emergence of drug-resistant bacterial strains is an issue to treat severe infections, and many efforts have identified new pharmacological agents. The inhibitors of β-lactamases (BLI) have gained a prominent role in the safeguard of beta-lactams. In the last years, new β-lactam–BLI combinations have been registered or are still under clinical evaluation, demonstrating their effectiveness to treat complicated infections. It is also noteworthy that the pharmacokinetics of BLIs partly matches that of β-lactams companions, meaning that some clinical situations, as well as renal impairment and renal replacement therapies, may alter the disposition of both drugs. Common pharmacokinetic characteristics, linear pharmacokinetics across a wide range of doses, and known pharmacokinetic/pharmacodynamic parameters may guide modifications of dosing regimens for both β-lactams and BLIs. However, comorbidities (i.e., burns, diabetes, cancer) and severe changes in individual pathological conditions (i.e., acute renal impairment, sepsis) could make dose adaptation difficult, because the impact of those factors on BLI pharmacokinetics is partly known. Therapeutic drug monitoring protocols may overcome those issues and offer strategies to personalize drug doses in the intensive care setting. Further prospective clinical trials are warranted to improve the use of BLIs and their β-lactam companions in severe and complicated infections.

Antimicrobial Dose Reduction in Continuous Renal Replacement Therapy: Myth or Real Need? A Practical Approach for Guiding Dose Optimization of Novel Antibiotics

Acute kidney injury represents a common complication in critically ill patients affected by septic shock and in many cases continuous renal replacement therapy (CRRT) may be required. In this scenario, antimicrobial dose optimization is highly challenging as the extracorporeal circuit may cause several pharmacokinetic alterations, which add up to volume of distribution and clearance variations resulting from sepsis. Variations in CRRT settings (i.e. modality of solute removal, type of filter material, blood flow rate and effluent flow rate), coupled with the presence of residual and/or recovering renal function, may cause dynamic variations in the clearance of hydrophilic antimicrobials. This means that dose reduction may not always be needed. Nowadays, the lack of pharmacokinetic data for novel antimicrobials during CRRT limits evidence-based dose recommendations for critically ill patients in this setting, thus making available evidence hardly applicable in real-world scenarios. This review aims to summarize the major determinants involved in antimicrobial clearance, and the available pharmacokinetic studies performed during CRRT involving novel antibiotics used for the management of multidrug-resistant Gram-positive and Gram-negative infections (namely ceftolozane–tazobactam, ceftazidime–avibactam, cefiderocol, imipenem–relebactam, meropenem–vaborbactam, ceftaroline, ceftobiprole, dalbavancin, and fosfomycin), providing a practical approach in guiding dose optimization in this special population.

Pharmacokinetic/pharmacodynamic target attainment in critically ill renal patients on antimicrobial usage: focus on novel beta-lactams and beta lactams/beta-lactamase inhibitors

INTRODUCTION

Several novel beta-lactams (BLs) and/or beta lactams/beta-lactamase inhibitors (BL/BLIs) have been recently developed for the management of multidrug-resistant bacterial infections. Data concerning dose optimization in critically ill patients with altered renal function are scanty.

AREAS COVERED

This article provides a critical reappraisal of pharmacokinetic and clinical issues emerged with novel BLs and/or BL/BLIs in renal critically ill patients. Clinical and pharmacokinetic studies published in English until December 2020 were searched on the PubMed-MEDLINE database.

EXPERT OPINION

Several issues emerged with the use of novel BLs and/or BL/BLIs in critically ill renal patients. Suboptimal clinical response rate with ceftazidime-avibactam and ceftolozane-tazobactam was reported in phase II-III trials in patients with moderate kidney injury; data on patients undergoing renal replacement therapy are limited to some case reports; dose adjustment in augmented renal clearance is provided only for cefiderocol. Implementation of altered dosing strategies (prolonged infusion and/or higher dosage) coupled with adaptive real-time therapeutic drug monitoring could represent the most effective approach in warranting optimal pharmacokinetic/pharmacodynamic targets with novel BLs and/or BL/BLIs in challenging scenarios, thus minimizing the risk of clinical failure and/or of resistance selection.

Minireview on Novel Anti-infectious Treatment Options and Optimized Drug Regimens for Sepsis

Sepsis, a life-threatening organ dysfunction caused by a dysregulated response to infection is a major public health concern, as it is a leading cause of mortality and critical illness worldwide. Antibiotics are one of the cornerstones of the treatment of sepsis; administering appropriate antibiotics in a rapid fashion to obtain adequate drug concentrations at the site of the infection can improve survival of patients. Nevertheless, it is a challenge for clinicians to do so. Indeed, clinicians today are regularly confronted with infections due to very resistant pathogens, and standard dosage regimens of antibiotics often do not provide adequate antibiotic concentrations at the site of the infection. We provide a narrative minireview of different anti-infectious treatments currently available and suggestions on how to deliver optimized dosage regimens to septic patients. Particular emphasis will be made on newly available anti-infectious therapies.

Nosocomial Pneumonia in the Era of Multidrug-Resistance: Updates in Diagnosis and Management

Nosocomial pneumonia (NP), including hospital-acquired pneumonia in non-intubated patients and ventilator-associated pneumonia, is one of the most frequent hospital-acquired infections, especially in the intensive care unit. NP has a significant impact on morbidity, mortality and health care costs, especially when the implicated pathogens are multidrug-resistant ones. This narrative review aims to critically review what is new in the field of NP, specifically, diagnosis and antibiotic treatment. Regarding novel imaging modalities, the current role of lung ultrasound and low radiation computed tomography are discussed, while regarding etiological diagnosis, recent developments in rapid microbiological confirmation, such as syndromic rapid multiplex Polymerase Chain Reaction panels are presented and compared with conventional cultures. Additionally, the volatile compounds/electronic nose, a promising diagnostic tool for the future is briefly presented. With respect to NP management, antibiotics approved for the indication of NP during the last decade are discussed, namely, ceftobiprole medocaril, telavancin, ceftolozane/tazobactam, ceftazidime/avibactam, and meropenem/vaborbactam.

Pharmacokinetics and dialytic clearance of apixaban during in vitro continuous renal replacement therapy

Background

To evaluate the transmembrane clearance (CL_TM) of apixaban during modeled in vitro continuous renal replacement therapy (CRRT), assess protein binding and circuit adsorption, and provide initial dosing recommendations.

Methods

Apixaban was added to the CRRT circuit and serial pre-filter bovine blood samples were collected along with post-filter blood and effluent samples. All experiments were performed in duplicate using continuous veno-venous hemofiltration (CVVH) and hemodialysis (CVVHD) modes, with varying filter types, flow rates, and point of CVVH replacement fluid dilution. Concentrations of apixaban and urea were quantified via liquid chromatography-tandem mass spectrometry. Plasma pharmacokinetic parameters for apixaban were estimated via noncompartmental analysis. CL_TM was calculated via the estimated area under the curve (AUC) and by the product of the sieving/saturation coefficient (SC/SA) and flow rate. Two and three-way analysis of variance (ANOVA) models were built to assess the effects of mode, filter type, flow rate, and point of dilution on CL_TM by each method. Optimal doses were suggested by matching the AUC observed in vitro to the systemic exposure demonstrated in Phase 2/3 studies of apixaban. Linear regression was utilized to provide dosing estimations for flow rates from 0.5–5 L/h.

Results

Mean adsorption to the HF1400 and M150 filters differed significantly at 38 and 13%, respectively, while mean (± standard deviation, SD) percent protein binding was 70.81 ± 0.01%. Effect of CVVH point of dilution did not differ across filter types, although CL_TM was consistently significantly higher during CRRT with the HF1400 filter compared to the M150. The three-way ANOVA demonstrated improved fit when CL_TM values calculated by AUC were used (adjusted R² 0.87 vs. 0.52), and therefore, these values were used to generate optimal dosing recommendations. Linear regression revealed significant effects of filter type and flow rate on CL_TM by AUC, suggesting doses of 2.5–7.5 mg twice daily (BID) may be needed for flow rates ranging from 0.5–5 L/h, respectively.

Conclusion

For CRRT flow rates most commonly employed in clinical practice, the standard labeled 5 mg BID dose of apixaban is predicted to achieve target systemic exposure thresholds. The safety and efficacy of these proposed dosing regimens warrants further investigation in clinical studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02248-7.

Population Pharmacokinetics and Pharmacodynamics of Meropenem in Critically Ill Pediatric Patients

This study investigates the optimal meropenem (MEM) dosing regimen for critically ill pediatric patients, for which there is a lack of pharmacokinetic (PK) studies. We conducted a retrospective single-center PK and pharmacodynamic (PD) analysis of 34 pediatric intensive care unit patients who received MEM. Individual PK parameters were determined by a two-compartment analysis. The median (range) age and body weight were 1.4 (0.03 to 14.6) years and 8.9 (2.7 to 40.9) kg, respectively, and eight (23.5%) patients received continuous renal replacement therapy (CRRT), three of whom received extracorporeal membrane oxygenation. Renal function, the systemic inflammatory response syndrome (SIRS) score for the clearance (CL), and the use of CRRT for the central volume of distribution (V _c) were identified as significant covariates. The mean CL, V _c, and peripheral volume of distribution (V _p) were 0.45 liters/kg/h, 0.49 liters/kg, and 0.34 liters/kg, respectively. The mean population CL of MEM increased by 35% in patients with SIRS and V _c increased by 66% in patients on CRRT in the final model. Dosing simulations suggested that the standard dosing regimen provided insufficient PD exposures of a 100% free time above the MIC, and higher doses (40 to 80 mg/kg of body weight/dose every 8 h) with a prolonged 3-h infusion were required to ensure the appropriate PD exposures for patients with SIRS. Our PK model indicated that critically ill pediatric patients are at risk of subtherapeutic exposure under the standard dosing regimen of MEM. A larger, prospective investigation confirming the safety and efficacy of higher concentrations and prolonged infusion of MEM is necessary.

An Appraisal of the Pharmacokinetic and Pharmacodynamic Properties of Meropenem-Vaborbactam

Carbapenem-resistant gram-negative pathogens remain an urgent public health threat, and safe, effective treatment options are limited. Although several agents are now available to combat these infections, meropenem-vaborbactam was the first to combine a novel, cyclic, boronic acid-based, β-lactamase inhibitor with a carbapenem backbone. Vaborbactam emanated from a discovery program specifically designed to identify candidate β-lactamase inhibitors with biochemical, microbiologic, and pharmacologic properties optimized for use in conjunction with a carbapenem. Meropenem was selected as the ideal carbapenem given its broad-spectrum in vitro activity, well established safety profile, and proven efficacy in the treatment of serious gram-negative infections. The combination has demonstrated potent in vitro activity against resistant gram-negative pathogens, particularly KPC-producing Klebsiella pneumoniae (MIC₅₀ values typically ≤ 0.06 mg/l). Importantly, the pharmacokinetic (PK) profiles of the two agents are well matched, and the approved optimized dosing regimen of 4 g every 8 h (Q8h) as a 3-h infusion provides reliable probability of target attainment against the majority of commonly encountered carbapenem-resistant Enterobacteriaceae (CRE). Robust in vitro and in vivo PK/pharmacodynamic (PD) data support the ability of this dosing regimen to achieve specified PK/PD targets for both bactericidal activity and prevention of resistance among pathogens with MICs up to 8 mg/l. This concerted effort into optimizing the PK and PD parameters of both the β-lactam and β-lactamase inhibitor alone and in combination contributed to the clinical success of meropenem-vaborbactam demonstrated in phase 3 trials in patients with complicated urinary tract infections (cUTI), including acute pyelonephritis (AP), and serious CRE infections. As the use of meropenem-vaborbactam increases concomitantly with the prevalence of KPC-producing CRE, continued pharmacovigilance and antimicrobial stewardship efforts will be of upmost importance to ensure that these PK/PD efforts translate into improved patient outcomes.

Recommendation of Antimicrobial Dosing Optimization During Continuous Renal Replacement Therapy

Continuous Renal Replacement Therapy (CRRT) is more and more widely used in patients for various indications recent years. It is still intricate for clinicians to decide a suitable empiric antimicrobial dosing for patients receiving CRRT. Inappropriate doses of antimicrobial agents may lead to treatment failure or drug resistance of pathogens. CRRT factors, patient individual conditions and drug pharmacokinetics/pharmacodynamics are the main elements effecting the antimicrobial dosing adjustment. With the development of CRRT techniques, some antimicrobial dosing recommendations in earlier studies were no longer appropriate for clinical use now. Here, we reviewed the literatures involving in new progresses of antimicrobial dosages, and complied the updated empirical dosing strategies based on CRRT modalities and effluent flow rates. The following antimicrobial agents were included for review: flucloxacillin, piperacillin/tazobactam, ceftriaxone, ceftazidime/avibactam, cefepime, ceftolozane/tazobactam, sulbactam, meropenem, imipenem, panipenem, biapenem, ertapenem, doripenem, amikacin, ciprofloxacin, levofloxacin, moxifloxacin, clindamycin, azithromycin, tigecycline, polymyxin B, colistin, vancomycin, teicoplanin, linezolid, daptomycin, sulfamethoxazole/trimethoprim, fluconazole, voriconazole, posaconzole, caspofungin, micafungin, amphotericin B, acyclovir, ganciclovir, oseltamivir, and peramivir.

Meropenem/vaborbactam: a next generation β-lactam β-lactamase inhibitor combination

INTRODUCTION

infections due to carbapenem-resistant Enterobacterales (CRE) constitute a worldwide threat and are associated with significant mortality, especially in fragile patients, and costs. Meropenem-vaborbactam (M/V) is a combination of a group 2 carbapenem with a novel cyclic boronic acid-based β-lactamase inhibitor which has shown good efficacy against KPC carbapenemase-producing Klebsiella pneumoniae, which are amongst the most prevalent types of CRE.

AREAS COVERED

This article reviews the microbiological and pharmacological profile and current clinical experience and safety of M/V in the treatment of infections caused by CRE.

EXPERT OPINION

M/V is a promising drug for the treatment of infections due to KPC-producing CRE (KPC-CRE). It exhibited an almost complete coverage of KPC-CRE isolates from large surveillance studies and a low propensity for resistance selection, retaining activity also against strains producing KPC mutants resistant to ceftazidime-avibactam. Both meropenem and vaborbactam have a favorable pharmacokinetic profile, with similar kinetic properties, a good intrapulmonary penetration, and are efficiently cleared during continuous venovenous hemofiltration (CVVH). According to available data, M/V monotherapy is associated with higher clinical cure rates and lower rates of adverse events, especially in terms of nephrotoxicity, if compared to 'older' combination therapies.

Diafiltration flowrate is a determinant of the extent of adsorption of amikacin in renal replacement therapy using the ST150®-AN69 filter: An in vitro study

Introduction:

In continuous renal replacement therapy, conduction and convection are controlled allowing prescribing dosage regimen improving survival. In contrast, adsorption is an uncontrolled property altering drug disposition. Whether adsorption depends on flowrates is unknown. We hypothesized an in vitro model may provide information in conditions mimicking continuous renal replacement therapy in humans.

Methods:

ST150®-AN69 filter and Prismaflex dialyzer, Baxter-Gambro were used. Simulated blood flowrate was set at 200 mL/min. The flowrates in the filtration (continuous filtration), dialysis (continuous dialysis), and diafiltration (continuous diafiltration) were 1500, 2500, and 4000 mL/h, respectively. Routes of elimination were assessed using NeckEpur® analysis.

Results:

The percentages of the total amount eliminated by continuous filtration, continuous dialysis, and continuous diafiltration were 82%, 86%, and 94%, respectively. Elimination by effluents and adsorption accounted for 42% ± 7% and 58% ± 5%, 57% ± 7% and 43% ± 6%, and 84% ± 6% and 16% ± 6% of amikacin elimination, respectively. There was a linear regression between flowrates and amikacin clearance: Y = 0.6 X ± 1.7 (R2 = 0.9782). Conversely, there was a linear inverse correlation between the magnitude of amikacin adsorption and flowrate: Y = –16.9 X ± 84.1 (R2 = 0.9976).

Conclusion:

Low flowrates resulted in predominant elimination by adsorption, accounting for 58% of the elimination of amikacin from the central compartment in the continuous filtration mode at 1500 mL/h of flowrate. Thereafter, the greater the flowrate, the lower the adsorption of amikacin in a linear manner. Flowrate is a major determinant of adsorption of amikacin. There was an about 17% decrease in the rate of adsorption per increase in the flowrate of 1 L/min.

Novel β-lactam-β-lactamase inhibitor combinations: expectations for the treatment of carbapenem-resistant Gram-negative pathogens

INTRODUCTION

The burden of antimicrobial resistance among Gram-negative bacteria is increasing and growing into a major threat of public health. Treatment options for carbapenem-resistant Enterobacteriaceae are limited and resistance rates to existing compounds are mounting. The pipeline includes only a small number of novel anti-infective agents in development or in the market with promising results against multidrug-resistant (MDR) Gram-negative. Areas covered: Herein the authors present the modern available knowledge regarding novel β-lactam-β-lactamase inhibitors, i.e. mechanisms of action, in vitro activity, current PK/PDs, clinical trials and clinical efficacy against MDR and XDR Gram-negatives, as well as toxicity issues. Expert opinion: Ceftazidime-avibactam and meropenem-vaborbactam are promising therapeutic options as both are active against Enterobacteriaceae producing ESBL, AmpC, and KPC, whereas only avibactam inhibits certain class D β-lactamases, mainly OXA-48. New drugs active against Gram-negative MDR isolates including imipenem/cilastatin with relebactam and avibactam combined with aztreonam or ceftaroline are in different stages of development. However, the disadvantage to be seriously considered by the clinician is that β-lactam/β-lactamase inhibitors are ineffective against metallo-β-lactamases (with the exception of aztreonam-avibactam) as well as Acinetobacter baumannii.