Edoxaban pharmacokinetics during in vitro continuous renal replacement therapy

BACKGROUND

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

METHODS

Edoxaban 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 edoxaban and urea were quantified via liquid chromatography-tandem mass spectrometry. Plasma pharmacokinetic parameters for edoxaban were estimated via noncompartmental analysis. 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 CLCRRT. Linear regression was utilized to provide dosing estimations across CRRT effluent flow rates from 0.5 to 5 L/h. Optimal edoxaban doses were suggested using CLCRRT and population non-renal clearance (CLNR) to estimate total clearance and match the systemic AUC associated with efficacy in the treatment of venous thromboembolism.

RESULTS

Edoxaban clearance from the CRRT circuit occurred primarily via hemofilter adsorption to the HF1400 and M150 filters at 74% and 65%, respectively, while mean percent protein binding was 41%. Multivariate analyses confirmed the lack of influence of CRRT mode, filter type, and point of dilution on the CLCRRT of edoxaban allowing dosing recommendations to be made based on effluent flow rate. Edoxaban doses of 30-45 mg once daily were estimated to achieve target the AUC threshold for flow rates from 0.5 to 5 L/h.

CONCLUSION

For CRRT flow rates most employed in clinical practice, an edoxaban dose of 45 mg once daily is predicted to achieve target systemic exposure thresholds for venous thromboembolism treatment. The safety and efficacy of this proposed dosing warrants further investigation in clinical studies.

Physiologically Based Pharmacokinetic Modelling in Critically Ill Children Receiving Anakinra While on Extracorporeal Life Support

BACKGROUND AND OBJECTIVE

Because of the pathophysiological changes associated with critical illness and the use of extracorporeal life support (ECLS) such as continuous renal replacement therapy (CRRT) and extracorporeal membrane oxygenation (ECMO), the pharmacokinetics of drugs are often altered. The objective of this study was to develop a physiologically based pharmacokinetic (PBPK) model for anakinra in children that accounts for the physiological changes associated with critical illness and ECLS technology to guide appropriate pharmacotherapy.

METHODS

A PBPK model for anakinra was first developed in healthy individuals prior to extrapolating to critically ill children receiving ECLS. To account for the impact of anakinra clearance by the dialysis circuit, a CRRT compartment was added to the pediatric PBPK model and parameterized using data from a previously published ex-vivo study. Additionally, an ECMO compartment was added to the whole-body structure to create the final anakinra ECLS-PBPK model. The final model structure was validated by comparing predicted concentrations with observed patient data. Due to limited information in guiding anakinra dosing in this population, in-silico dose simulations were conducted to provide baseline recommendations.

RESULTS

By accounting for changes in physiology and the addition of ECLS compartments, the final ECLS-PBPK model predicted the observed plasma concentrations in an adolescent receiving subcutaneous anakinra. Furthermore, dosing simulations suggest that anakinra exposure in adolescents receiving ECLS is similar to that in healthy counterparts.

CONCLUSION

The anakinra ECLS-PBPK model developed in this study is the first to predict plasma concentrations in a population receiving simultaneous CRRT and ECMO. Dosing simulations provided may be used to inform anakinra use in critically ill children and guide future clinical trial planning.

Anakinra Removal by Continuous Renal Replacement Therapy: An Ex Vivo Analysis

OBJECTIVES

Patients with sepsis are at significant risk for multiple organ dysfunction, including the lungs and kidneys. To manage the morbidity associated with kidney impairment, continuous renal replacement therapy (CRRT) may be required. The extent of anakinra pharmacokinetics in CRRT remains unknown. The objectives of this study were to investigate the anakinra-circuit interaction and quantify the rate of removal from plasma.

DESIGN

The anakinra-circuit interaction was evaluated using a closed-loop ex vivo CRRT circuit. CRRT was performed in three phases based on the method of solute removal: 1) hemofiltration, 2) hemodialysis, and 3) hemodiafiltration. Standard control samples of anakinra were included to assess drug degradation.

SETTING

University research laboratory.

PATIENTS

None.

INTERVENTIONS

Anakinra was administered to the CRRT circuit and serial prefilter blood samples were collected along with time-matched control and hemofiltrate samples. Each circuit was run in triplicate to assess inter-run variability. Concentrations of anakinra in each reference fluid were measured by enzyme-linked immunosorbent assay. Transmembrane filter clearance was estimated by the product of the sieving coefficient/dialysate saturation constant and circuit flow rates.

MEASUREMENTS AND MAIN RESULTS

Removal of anakinra from plasma occurred within minutes for each CRRT modality. Average drug remaining (%) in plasma following anakinra administration was lowest with hemodiafiltration (34.9%). The average sieving coefficient was 0.34, 0.37, and 0.41 for hemodiafiltration, hemofiltration, and hemodialysis, respectively. Transmembrane clearance was fairly consistent across each modality with the highest during hemodialysis (5.53 mL/min), followed by hemodiafiltration (4.99 mL/min), and hemofiltration (3.94 mL/min). Percent drug remaining within the control samples (93.1%) remained consistent across each experiment, indicating negligible degradation within the blood.

CONCLUSIONS

The results of this analysis are the first to demonstrate that large molecule therapeutic proteins such as anakinra, are removed from plasma with modern CRRT technology. Current dosing recommendations for patients with severe renal impairment may result in subtherapeutic anakinra concentrations in those receiving CRRT.

Medication Management in the Critically Ill Patient with Acute Kidney Injury

ABSTRACT

AKI occurs frequently in critically ill patients. Patients with AKI, including those who require KRT, experience multiple pharmacokinetic and pharmacodynamic perturbations that dynamically influence medication effectiveness and safety. Patients with AKI may experience both subtherapeutic drug concentrations, which lead to ineffective therapy, and supratherapeutic drug concentrations, which increase the risk for toxicity. In critically ill patients with AKI not requiring KRT, conventional GFR estimation equations, especially those based on serum creatinine, have several limitations that can limit the accuracy when used for medication dosing. Alternative methods to estimate kidney function may be informative, including use of measured urinary creatinine clearance, kinetic eGFR, and equations that integrate novel kidney biomarkers. For critically ill patients with AKI requiring KRT, physicochemical properties of the drug, the KRT prescription and circuit configuration, and patient-specific factors each contribute to medication clearance. Evidence-based guidance for medication dosing during AKI requiring KRT is often limited. A working knowledge of the basic tenets of drug elimination during KRT can provide a framework for how to approach decision making when the literature is lacking. Iterative re-evaluation of a patient's progress toward therapeutic goals with a medication must occur over the arc of critical illness, including and especially in the setting of dynamic kidney function.

Pharmacokinetics in Critically Ill Children with Acute Kidney Injury

Acute kidney injury (AKI) is a commonly encountered comorbidity in critically ill children. The coexistence of AKI disturbs drug pharmacokinetics and pharmacodynamics, leading to clinically significant consequences. This can complicate an already critical clinical scenario by causing potential underdosing or overdosing giving way to possible therapeutic failures and adverse reactions. Current available studies offer little guidance to help maneuver such complex dosing regimens and decision-making in pediatric patients as most of them are done on heterogeneous groups of adult populations. Though there are some studies on drug dosing during continuous renal replacement therapy (CRRT), their utility is in question because of the recent advances in CRRT technology. Our review aims to discuss the principles of pharmacokinetics pertinent for honing the existing practices of drug dosing in critically ill children with AKI, and the various complexities and intricate challenges involved. This in turn will provide a framework to help enable caretakers to tailor dosing regimens in complex clinical setups with further ease and precision.

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.

Therapeutic Drug Monitoring of Antibiotic Drugs in Patients Receiving Continuous Renal Replacement Therapy or Intermittent Hemodialysis: A Critical Review

PURPOSE

Antibiotics are frequently used in patients receiving intermittent or continuous renal replacement therapy (RRT). Continuous renal replacement may alter the pharmacokinetics (PK) and the ability to achieve PK/pharmacodynamic (PD) targets. Therapeutic drug monitoring (TDM) could help evaluate drug exposure and guide antibiotic dosage adjustment. The present review describes recent TDM data on antibiotic exposure and PK/PD target attainment (TA) in patients receiving intermittent or continuous RRT, proposing practical guidelines for performing TDM.

METHODS

Studies on antibiotic TDM performed in patients receiving intermittent or continuous RRT published between 2000 and 2020 were searched and assessed. The authors focused on studies that reported data on PK/PD TA. TDM recommendations were based on clinically relevant PK/PD relationships and previously published guidelines.

RESULTS

In total, 2383 reports were retrieved. After excluding nonrelevant publications, 139 articles were selected. Overall, 107 studies reported PK/PD TA for 24 agents. Data were available for various intermittent and continuous RRT techniques. The study design, TDM practice, and definition of PK/PD targets were inconsistent across studies. Drug exposure and TA rates were highly variable. TDM seems to be necessary to control drug exposure in patients receiving intermittent and continuous RRT techniques, especially for antibiotics with narrow therapeutic margins and in critically ill patients. Practical recommendations can provide insights on relevant PK/PD targets, sampling, and timing of TDM for various antibiotic classes.

CONCLUSIONS

Highly variable antibiotic exposure and TA have been reported in patients receiving intermittent or continuous RRT. TDM for aminoglycosides, beta-lactams, glycopeptides, linezolid, and colistin is recommended in patients receiving RRT and suggested for daptomycin, fluoroquinolones, and tigecycline in critically ill patients on RRT.

Beta-lactam dosing during continuous renal replacement therapy: a survey of practices in french intensive care units

Background

Little information is available on current practice in beta-lactam dosing during continuous renal replacement therapy (CRRT). Optimized dosing is essential for improving outcomes, and there is no consensus on the appropriate dose regimens. The objective of the present study was to describe current practice for beta-lactam dosing during CRRT in intensive care units (ICUs).

Methods

We conducted a nationwide survey by e-mailing an online questionnaire to physicians working in ICUs in France. The questionnaire included three sections: demographic characteristics, CRRT practices, and beta-lactam dosing regimens during CRRT.

Results

157 intensivists completed the questionnaire. Continuous venovenous hemofiltration was the most frequently used CRRT technique, and citrate was the most regularly used anticoagulant. The median prescribed dose at baseline was 30 mL/kg/h. The majority of prescribers (57%) did not reduce beta-lactam dosing during CRRT. The tools were used to adapt dosing regimens during CRRT included guidelines, therapeutic drug monitoring (TDM), and data from the literature. When TDM was used, 100% T > 4 time the MIC was the most common mentioned pharmacokinetic/pharmacodynamic target (53%). Pharmacokinetic software tools were rarely used. Prolonged or continuous infusions were widely used during CRRT (88%). Institutional guidelines on beta-lactam dosing during CRRT were rare. 41% of physicians sometimes consulted another specialist before adapting the dose of antibiotic during CRRT.

Conclusions

Our present results highlight the wide range of beta-lactam dosing practices adopted during CRRT. Personalized TDM and the implementation of Bayesian software appear to be essential for optimizing beta-lactam dosing regimens and improving patient outcomes.

The use of a modified Delphi technique to develop a critical appraisal tool for clinical pharmacokinetic studies

BACKGROUND

Critical appraisal aids in assessing the quality of scientific literature, which is central to the practice of evidence-based medicine. Several tools and guidelines are available for critiquing and assessing the quality of specific study types. However, limited guidance exists for critical appraisal of clinical pharmacokinetic studies.

AIM

We aimed to achieve experts' consensus regarding the quality markers for clinical pharmacokinetic studies in an attempt to develop a critical appraisal tool.

METHOD

Quality markers related to clinical pharmacokinetic studies, were derived from the published literature and categorized according to manuscript reporting domains (abstract, introduction/background, methodology, results, discussion, and conclusion). Questions that aid in appraising pharmacokinetic studies were formulated from these quality markers. Experts were involved in a modified Delphi process to achieve a consensus regarding the formulated questions. The proposed tool was pilot tested on 30 recently published clinical pharmacokinetic studies. Inter-observer agreement was measured to determine the reliability of the included items.

RESULTS

Twenty-five experts consented to participate. Three rounds of a modified Delphi survey were required to generate a consensus for a 21-item tool aimed at appraising the quality of clinical pharmacokinetic studies. When applied to 30 recently published clinical pharmacokinetic studies, most items scored fair to moderate levels of agreement (61.90-95.24%).

CONCLUSION

The clinical pharmacokinetic critical appraisal tool (CACPK) developed in this study consisted of 21 items aimed at helping an end-user to determine the quality of a pharmacokinetic study. Further studies are warranted to reaffirm the validity and reliability of the CACPK tool.

Enhanced loading dose of teicoplanin for three days is required to achieve a target trough concentration of 20 μg/mL in patients receiving continuous venovenous haemodiafiltration with a low flow rate

INTRODUCTION

Because of its lower risk of renal toxicity than vancomycin, teicoplanin is the preferred treatment for methicillin-resistant Staphylococcus aureus infection in patients undergoing continuous venovenous haemodiafiltration (CVVHDF) in whom renal function is expected to recover. The dosing regimen for achieving a trough concentration (C_min) of ≥20 μg/mL remains unclear in patients on CVVHDF using the low flow rate adopted in Japan.

METHODS

The study was conducted in patients undergoing CVVHDF with a flow rate of <20 mg/kg/h who were treated with teicoplanin. We adopted three loading dose regimens for the initial 3 days: the conventional regimen, a high-dose regimen (four doses of 10 mg/kg), and an enhanced regimen (four doses of 12 mg/kg). The initial C_min was obtained at 72 h after the first dose.

RESULTS

Overall, 60 patients were eligible for study inclusion. The proportion of patients achieving the C_min target was significantly higher for the enhanced regimen than for the high-dose regimen (52.9% versus 8.3%, p = 0.003). In multivariate analysis, the enhanced regimen (odds ratio [OR] = 39.93, 95% confidence interval [CI] = 5.03-317.17) and hypoalbuminaemia (OR = 0.04, 95% CI = 0.01-0.44) were independent predictors of the achievement of C_min ≥ 20 μg/mL.

CONCLUSIONS

An enhanced teicoplanin regimen was proposed to treat complicated or invasive infections by methicillin-resistant Staphylococcus aureus in patients receiving CVVHDF even with a low flow rate.

Therapeutic Modulation of the Host Defense by Hemoadsorption with CytoSorb®-Basics, Indications and Perspectives-A Scoping Review

The "normal" immune response to an insult triggers a highly regulated response determined by the interaction of various immunocompetent cells with pro- and anti-inflammatory cytokines. Under pathologic conditions, the massive elevation of cytokine levels ("cytokine storm") could not be controlled until the recent development of hemoadsorption devices that are able to extract a variety of different DAMPs, PAMPs, and metabolic products from the blood. CytoSorb® has been approved for adjunctive sepsis therapy since 2011. This review aims to summarize theoretical knowledge, in vitro results, and clinical findings to provide the clinician with pragmatic guidance for daily practice. English-language and peer-reviewed literature identified by a selective literature search in PubMed and published between January 2016 and May 2021 was included. Hemoadsorption can be used successfully as adjunct to a complex therapeutic regimen for various conditions. To the contrary, this nonspecific intervention may potentially worsen patient outcomes in complex immunological processes. CytoSorb® therapy appears to be safe and useful in various diseases (e.g., rhabdomyolysis, liver failure, or intoxications) as well as in septic shock or cytokine release syndrome, although a conclusive assessment of treatment benefit is not possible and no survival benefit has yet been demonstrated in randomized controlled trials.

Imipenem dosing recommendations for patients undergoing continuous renal replacement therapy: systematic review and Monte Carlo simulations

Background

The appropriate dosing of imipenem for critically ill AKI patients undergoing CRRT remains scarce.

Purpose

This study aimed to (1) gather the available published pharmacokinetic studies conducted in septic patients receiving continuous renal replacement therapy (CRRT) and (2) to define the optimal imipenem dosing regimens in these populations via Monte Carlo simulations.

Methods

The databases of PubMed, Embase, and ScienceDirect were searched from inception to May 2020. We used the Medical Subject Headings of “Imipenem,” “CRRT,” and “pharmacokinetics” or related terms or synonym to identify the studies for systematic reviews. A one-compartment pharmacokinetic model was conducted to predict imipenem levels for the initial 48 h of therapy. The pharmacodynamic target was 40% of free drug level above 4 times of the MIC (40% fT > 4 MIC). The dose that achieved at least 90% of the probability of target attainment was defined as an optimal dose.

Results

Eleven articles were identified and included for our systematic review. The necessary pharmacokinetic parameters such as the volume of distribution and the CRRT clearance were mentioned in 100 and 90.9%, respectively. None of the current studies reported the complete necessary parameters. A regimen of 750 mg q 6 h was the optimal dose for the predilution-CVVH and CVVHD modality with two effluent rates (25 and 35 mL/kg/h) for the pharmacodynamic target of 40% fT > 4MIC.

Conclusions

None of the current studies showed the complete necessary pharmacokinetic parameters for drug dosing. Pharmacodynamic target significantly contributed to imipenem dosing regimens in these patients. Different effluent rates and types of CRRT had minimal impact on dosing regimens. Clinical validation of the recommendation is necessary.

Pericarditis Caused by Enterococcus faecium with Acute Liver Failure Treated by a Multifaceted Approach including Antimicrobials and Hemoadsorption

Background

Sepsis and septic shock are still life-threatening diseases with a high mortality rate. We report a complex case of peritonitis with pericarditis and acute liver failure caused by septic shock. Potentially hepatotoxic antibiotic therapy levels were monitored using the liver maximum capacity (LiMAx®) test, and standard treatment was supplemented by adjunctive hemoadsorption with CytoSorb®. Case Presentation. The case features a 29-year-old woman with a history of Crohn's disease and cachexia. Peritonitis caused by Enterococcus faecium was diagnosed later due to an ileum perforation. The hematogenic spread led to pericarditis. In addition, sepsis-related acute liver failure complicated antimicrobial therapy further. The combination of standard therapy, anti-infective medication, and blood purification was associated with inflammation control, hemodynamic stabilization, and a concomitant decrease in vasopressor support. An efficient, sustained reduction in plasma bilirubin levels was achieved while maintaining liver function.

Conclusions

This case shows how complex infectious diseases with an atypical infectious focus resulting in septic shock can be successfully treated. A combination of antimicrobial (tigecycline and caspofungin) and long-term adjunctive hemoadsorption therapy was administered while hepatotoxic antibiotic medication was monitored by liver function testing.

Once-daily 1 g ceftriaxone optimizes exposure in patients with septic shock and hypoalbuminemia receiving continuous veno-venous hemodiafiltration

PURPOSE

Ceftriaxone total and unbound pharmacokinetics (PK) can be altered in critically ill patients with septic shock and hypoalbuminemia receiving continuous veno-venous hemodiafiltration (CVVHDF). The objective of this study was to determine the dosing strategy of ceftriaxone that maximizes the probability of maintaining the concentration above the MIC of the susceptible bacteria (≤2 mg/L by the EUCAST) for a 100% of the dosing interval (100% ƒ_uT_>MIC).

METHODS

In a prospective PK study in the intensive care units of two tertiary Spanish hospitals, six timed blood samples were collected per patient; for each sample, ceftriaxone total and unbound concentrations were measured using a liquid chromatography coupled to tandem mass spectrometry method. Population PK analysis and Monte-Carlo simulations were performed using NONMEMv.7.3®.

RESULTS

We enrolled 8 critically ill patients that met the inclusion criteria (47 blood samples). Median age (range) was 70 years (47-85), weight 72.5 kg (40-95), albumin concentration 24.2 g/L (22-34), APACHE II score at admission 26 (17-36), and SOFA score on the day of study 12 (9-15). The unbound fraction (ƒ_u) of ceftriaxone was 44%, and total CL was 1.27 L/h, 25-30% higher than the CL reported in septic critically ill patients not receiving renal replacement therapies, and dependent on albumin concentration and weight. Despite this increment in ƒ_u and CL, Monte-Carlo simulations showed that a dose of 1 g once-daily ceftriaxone is sufficient to achieve a 100% ƒ_uT_>MIC for MICs ≤2 mg/L for any range of weight and albumin concentration.

CONCLUSION

Once-daily 1 g ceftriaxone provides optimal exposure in critically ill patients with septic shock and hypoalbuminemia receiving CVVHDF.

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.

Factors increasing the risk of inappropriate vancomycin therapy in ICU patients: A prospective observational study

BACKGROUND

Vancomycin trough levels are frequently subtherapeutic in intensive care unit (ICU) patients. The aim of this study was to identify patients at risk of therapeutic failure defined as vancomycin area-under-the-curve_0-24 /minimum inhibitory concentration (AUC_0-24 /MIC) <400, and to examine possible effects of different MICs, the variability in renal clearance and continuous renal replacement therapy (CRRT), and the relevance of vancomycin therapy.

METHODS

A prospective observational study of ICU patients ≥ 18 years at initiation of vancomycin therapy was conducted from May 2013 to October 2015. The patients were divided into four groups according to renal function and CRRT-mode as follows: normal- or augmented renal clearance and continuous venovenous hemodialysis or -hemofiltration. Vancomycin peak and trough levels were measured at 24, 48, and 72 hours after therapy initiation. Relevance of vancomycin therapy was retrospectively evaluated based on microbiological results.

RESULTS

Eighty-three patients were included, median age 54.5 years, 74.5% male, SAPS II score 46, and 90 day mortality 28%. Vancomycin therapy was initiated on ICU-day 8 (IQR, 5-12), with a median treatment time of 7.5 (IQR, 5-12) days. AUC_0-24 /MIC > 400 was reached in 81% and 8% with MIC = 1 and 2 mg/L respectively. The CRRT groups had higher AUC_0-24 /MIC-ratios than the non-CRRT groups (P < .001). Augmented renal clearance increased the risk of AUC_0-24 /MIC < 400, independent of MIC-value. Initiation of vancomycin therapy was retrospectively considered relevant in 28 patients (34%).

CONCLUSION

A MIC-value >1 mg/L and augmented renal clearance, were factors increasing the risk of therapeutic failure. Vancomycin treatments could have been omitted or shortened in most of these patients.

An Integrated Dialysis Pharmacometric (IDP) Model to Evaluate the Pharmacokinetics in Patients Undergoing Renal Replacement Therapy

PURPOSE

Clearance via renal replacement therapy (RRT) can significantly alter the pharmacokinetic profile of drugs. The aim of this study was (i) to improve the use of clinical trial data and (ii) to provide a model that allows quantification of all aspects of drug elimination via RRT including adsorption to dialysis membranes and/or degradation of the drug in the dialysate.

METHODS

An integrated dialysis pharmacometric (IDP) model was developed to simultaneously incorporate all available RRT information. The sensitivity, accuracy and precision of the IDP model was compared to conventional approaches in clinical trial simulations and applied to clinical datasets of teicoplanin and doripenem.

RESULTS

The IDP model was more accurate, precise and sensitive than conventional plasma-concentration-based approaches when estimating the clearanceRRT (relative bias <1%). In contrast to conventional approaches, adsorption and degradation were quantifiable using the IDP model (relative bias: -1.1% and - 1.9%, respectively). Applied to clinical data, clearanceRRT, drug degradation (effluent-half-lifedoripenem: 13.5 h-1) and adsorption (polysulphone adsorption capacityteicoplanin: 31.2 mg) were assessed.

CONCLUSION

The IDP model allows accurate, precise and sensitive characterization of clearanceRRT, adsorption and degradation. Successful quantification of all aspects of clearanceRRT in clinical data demonstrated the benefit of the IDP model as compared to conventional approaches.

A Robust Statistical Approach to Analyse Population Pharmacokinetic Data in Critically Ill Patients Receiving Renal Replacement Therapy

BACKGROUND AND AIM

Current approaches to antibiotic dose determination in critically ill patients requiring renal replacement therapy are primarily based on the assessment of highly heterogeneous data from small number of patients. The standard modelling approaches limit the scope of constructing robust confidence boundaries of the distribution of pharmacokinetics (PK) parameters, especially when the evaluation of possible association of demographic and clinical factors at different levels of the distribution of drug clearance is of interest. Commonly used compartmental models generally construct the inferences through a linear or non-linear mean regression, which is inadequate when the distribution is skewed, multi-modal or effected by atypical observation. In this study, we discuss the statistical challenges in robust estimation of the confidence boundaries of the PK parameters in the presence of highly heterogenous patient characteristics.

METHODS

A novel stepwise approach to evaluate the confidence boundaries of PK parameters is proposed by combining PK modelling with mixed-effects quantile regression (MEQR) methods.

RESULTS

This method allows the assessment demographic and clinical factors' effects at any arbitrary quantiles of the outcome of interest, without restricting assumptions on the distributions. The MEQR approach allows us to investigate if the levels of association of the covariates are different at low, medium or high concentration.

CONCLUSIONS

This methodological assessment is deemed as a background initial approach to support the development of a class of statistical algorithm in constructing robust confidence intervals of PK parameters which can be used for developing an optimised antibiotic dosing guideline for critically ill patients requiring renal replacement therapy.

LC-MS/MS method for simultaneous determination of linezolid, meropenem, piperacillin and teicoplanin in human plasma samples

Antibiotic therapy is a crucial aspect of the management of hospitalized patients, however, current standard dosing protocols have been shown to often attain inadequate plasmatic concentrations which may impair the clinical outcome and promote the selection of multidrug-resistant bacteria. The aim of this study is to establish and validate a robust and fast liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous analysis of four commonly used antibiotics (Meropenem, Piperacillin, Linezolid and Teicoplanin) in human plasma according to the European Medicines Agency (EMA) guidelines. Samples preparation was performed using a commercially available extraction kit which needs a very small amount of sample (50 μl). Antibiotics were detected, following a 7 min gradient separation, in multiple reactions monitoring (MRM) mode using a Qtrap 5500 triple quadrupole instrument equipped with an electrospray source operating in positive ion mode. The method, covering the antibiotics' clinically relevant concentration ranges, is also able to quantify, individually, the major teicoplanin components. The high reproducibility and the need of a small amount of sample, associated with the use of a commercial kit, together with a short chromatographic time, makes the method particularly suited for high-throughput routine analysis. Monitoring of plasma antibiotic levels, as part of the clinical routine, would result in a quick therapy adjustment leading to a higher probability of eradicating the infection as well as a potential reduction of multidrug-resistance prevalence. The method was successfully applied to monitor the antibiotic concentration of 49 patients under therapy.

High variability of teicoplanin concentration in patients with continuous venovenous hemodiafiltration

INTRODUCTION

Continuous venovenous hemodiafiltration (CVVHDF) may alter teicoplanin pharmacokinetics and increase the risk of incorrect dosing. The objective of this prospective observational study was to assess the effect of CVVHDF on the pharmacokinetics of teicoplanin as maintenance therapy.

METHODS

Blood, urine, and dialysate samples were collected to measure teicoplanin levels. CVVHDF clearance (CL_CVVHDF ), total clearance (CL_TOTAL ), and volume of distribution (Vd) were calculated by simplex-linear modeling. The influence of CVVHDF dose on teicoplanin pharmacokinetics was assessed.

FINDINGS

Ten samples from eight patients were studied. Creatinine clearance was 3.4 ± 5.1 ml/min/1.73 m² . Three patients were anuria. The dose for CVVHDF was 32.1 ± 7.0 mL/kg/h. Vd was 1.6 ± 0.7 L/kg. T1/2 was 100.1 ± 42.7 hours. CL_TOTAL of teicoplanin was 11.9 ± 5.4 mL/min and CL_CVVHDF was 5.8 ± 4.2 mL/min. Contribution of CL_CVVHDF to CL_TOTAL was 51.2% ± 23.6%. CL_CVVHDF of individual teicoplanin varied widely. Large intra-occasion differences were also observed. Dose of CL_CVVHDF did not influence overall CL_TOTAL , Vd, or half-life. The proportion of CL_TOTAL due to CL_CVVHDF varied widely. It was high in some cases.

DISCUSSION

In patients receiving CVVHDF, there is great variability in teicoplanin pharmacokinetics which complicates empiric approach to dosing, suggesting the need for therapeutic drug monitoring.

Tigecycline in critically ill patients on continuous renal replacement therapy: a population pharmacokinetic study

Background

Tigecycline is a vital antibiotic treatment option for infections caused by multiresistant bacteria in the intensive care unit (ICU). Acute kidney injury (AKI) is a common complication in the ICU requiring continuous renal replacement therapy (CRRT), but pharmacokinetic data for tigecycline in patients receiving CRRT are lacking.

Methods

Eleven patients mainly with intra-abdominal infections receiving either continuous veno-venous hemodialysis (CVVHD, n = 8) or hemodiafiltration (CVVHDF, n = 3) were enrolled, and plasma as well as effluent samples were collected according to a rich sampling schedule. Total and free tigecycline was determined by ultrafiltration and high-performance liquid chromatography (HPLC)-UV. Population pharmacokinetic modeling using NONMEM® 7.4 was used to determine the pharmacokinetic parameters as well as the clearance of CVVHD and CVVHDF. Pharmacokinetic/pharmacodynamic target attainment analyses were performed to explore the potential need for dose adjustments of tigecycline in CRRT.

Results

A two-compartment population pharmacokinetic (PK) model was suitable to simultaneously describe the plasma PK and effluent measurements of tigecycline. Tigecycline dialysability was high, as indicated by the high mean saturation coefficients of 0.79 and 0.90 for CVVHD and CVVHDF, respectively, and in range of the concentration-dependent unbound fraction of tigecycline (45–94%). However, the contribution of CRRT to tigecycline clearance (CL) was only moderate (CL_CVVHD: 1.69 L/h, CL_CVVHDF: 2.71 L/h) in comparison with CL_body (physiological part of the total clearance) of 18.3 L/h. Bilirubin was identified as a covariate on CL_body in our collective, reducing the observed interindividual variability on CL_body from 58.6% to 43.6%. The probability of target attainment under CRRT for abdominal infections was ≥ 0.88 for minimal inhibitory concentration (MIC) values ≤ 0.5 mg/L and similar to patients without AKI.

Conclusions

Despite high dialysability, dialysis clearance displayed only a minor contribution to tigecycline elimination, being in the range of renal elimination in patients without AKI. No dose adjustment of tigecycline seems necessary in CRRT.

Trial registration

EudraCT, 2012–005617-39. Registered on 7 August 2013.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2278-4) contains supplementary material, which is available to authorized users.

Cefepime dosing regimens in critically ill patients receiving continuous renal replacement therapy: a Monte Carlo simulation study

Background

Cefepime can be removed by continuous renal replacement therapy (CRRT) due to its pharmacokinetics. The purpose of this study is to define the optimal cefepime dosing regimens for critically ill patients receiving CRRT using Monte Carlo simulations (MCS).

Methods

The CRRT models of cefepime disposition during 48 h with different effluent rates were developed using published pharmacokinetic parameters, patient demographic data, and CRRT settings. Pharmacodynamic target was the cumulative percentage of a 48-h period of at least 70% that free cefepime concentration exceeds the four times susceptible breakpoint of Pseudomonas aeruginosa (minimum inhibitory concentration, MIC of 8). All recommended dosing regimens from available clinical resources were evaluated for the probability of target attainment (PTA) using MCS to generate drug disposition in a group of 5000 virtual patients for each dose. The optimal doses were defined as achieving the PTA at least 90% of virtual patients with lowest daily doses and the acceptable risk of neurotoxicity.

Results

Optimal cefepime doses in critically ill patients receiving CRRT with Kidney Disease: Improving Global Outcomes (KDIGO) recommended effluent rates were a regimen of 2 g loading dose followed by 1.5–1.75 g every 8 h for Gram-negative infections with a neurotoxicity risk of < 17%. Cefepime dosing regimens from this study were considerably higher than the recommended doses from clinical resources.

Conclusion

All recommended dosing regimens for patients receiving CRRT from available clinical resources failed to achieve the PTA target. The optimal dosing regimens were suggested based on CRRT modalities, MIC values, and different effluent rates. Clinical validation is warranted.

Optimisation of antimicrobial dosing based on pharmacokinetic and pharmacodynamic principles

While suboptimal dosing of antimicrobials has been attributed to poorer clinical outcomes, clinical cure and mortality advantages have been demonstrated when target pharmacokinetic (PK) and pharmacodynamic (PD) indices for various classes of antimicrobials were achieved to maximise antibiotic activity. Dosing optimisation requires a good knowledge of PK/PD principles. This review serves to provide a foundation in PK/PD principles for the commonly prescribed antibiotics (β-lactams, vancomycin, fluoroquinolones and aminoglycosides), as well as dosing considerations in special populations (critically ill and obese patients). PK principles determine whether an appropriate dose of antimicrobial reaches the intended pathogen(s). It involves the fundamental processes of absorption, distribution, metabolism and elimination, and is affected by the antimicrobial's physicochemical properties. Antimicrobial pharmacodynamics define the relationship between the drug concentration and its observed effect on the pathogen. The major indicator of the effect of the antibiotics is the minimum inhibitory concentration. The quantitative relationship between a PK and microbiological parameter is known as a PK/PD index, which describes the relationship between dose administered and the rate and extent of bacterial killing. Improvements in clinical outcomes have been observed when antimicrobial agents are dosed optimally to achieve their respective PK/PD targets. With the rising rates of antimicrobial resistance and a limited drug development pipeline, PK/PD concepts can foster more rational and individualised dosing regimens, improving outcomes while simultaneously limiting the toxicity of antimicrobials.

Simultaneous quantification of cefepime, meropenem, ciprofloxacin, moxifloxacin, linezolid and piperacillin in human serum using an isotope-dilution HPLC-MS/MS method

The aim of the current study was to develop and validate a robust multi-analyte high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method for simultaneous quantification of cefepime, meropenem, ciprofloxacin, moxifloxacin, linezolid and piperacillin, which are the most commonly used antibiotics in intensive care units. Sample clean-up included a protein precipitation protocol, followed by chromatographic separation on a C₈ reverse phase HPLC column within 4 min, using a formic acid-ammonium formiate methanol step-elution gradient. All compounds were detected with electrospray ionization (ESI+) mass spectrometry in multiple reaction time monitoring. The method was validated according to the protocol from the European Medicines Agency and was thoroughly evaluated for interferences and quantification linearity. Linear relationships between peak area responses and drug concentrations were obtained in the range of 0.25-200 mg/l for cefepime, 0.25-120 mg/l for meropenem, 0.05-10 mg/l for ciprofloxacin, 0.125-10 mg/l for moxifloxacin, 0.125-50 mg/l for linezolid and 0.5-400 mg/l for piperacillin with an R² > 0.997. Imprecision and inaccuracy values (both intra- and inter-assay) were ≤ 6.8% and ≤10.9% for all analytes in quality control samples, respectively. The assay proved to be selective for the study antibiotics, and the internal standards consistently compensated for matrix effects. The described simple and reliable HPLC-MS/MS assay is a powerful tool for routine TDM of cefepime, meropenem, ciprofloxacin, moxifloxacin, linezolid and piperacillin in human serum in clinical laboratories. With a total process time of approximately 30 min, it allows for accurate and selective quantification up to the expected pharmacokinetic peak concentrations.

Considerations for Medication Management and Anticoagulation During Continuous Renal Replacement Therapy

Providing safe and high-quality care to critically ill patients receiving continuous renal replacement therapy (CRRT) includes adequate drug dosing and evaluation of patients' response to medications during therapy. Pharmacokinetic drug studies in acute kidney injury and CRRT are limited, considering the number of medications used in critical care. Therefore, it is important to understand the basic principles of drug clearance during CRRT by evaluating drug properties, CRRT modalities, and how they affect medication clearance. Few published studies have addressed drug disposition and clinical response during CRRT. Additionally, clotting in the CRRT circuit is a concern, so a few options for anticoagulation strategies are presented. This article reviews (1) the CRRT system and drug property factors that affect medication management, (2) the evidence available to guide drug dosing, and (3) anticoagulation strategies for critically ill patients receiving CRRT.

Guidance to develop individual dose recommendations for patients on chronic hemodialysis

INTRODUCTION

In addition to tailored clinical trials in patients on chronic hemodialysis (HD) during drug development, clinician-initiated post-marketing studies and case reports on individual pharmacokinetic (PK) assessments provide an important source of information about drug dialysability and individualized dose recommendations in this vulnerable population. Areas covered: First, factors that may alter drug exposure in HD patients are explained. Second, available regulatory and methodological guidelines for PK assessments in this population are summarized. Third, a 4-step approach is proposed to develop individual dose recommendations for HD patients receiving drugs without data from a PK study: (1) literature search, (2) model-based dosage decisions, (3) validation and refinement through concentration monitoring, and (4) publication of relevant observations. Fourth, clinician-initiated PK assessments and case reports to evaluate and individualize use of drugs in HD patients are reviewed, and recommendations to enhance their quality are discussed. Expert commentary: Guidance on collecting and reporting PK information in individual HD patients is warranted to ensure completeness and consistency of such PK studies. A checklist and template for easy-to-implement PK calculations and pharmacometric modeling is provided to facilitate evaluation and individualization of dosing strategies in these patients.

Prolonged infusion of sedatives and analgesics in adult intensive care patients: A systematic review of pharmacokinetic data reporting and quality of evidence

Although pharmacokinetic (PK) data for prolonged sedative and analgesic agents in intensive care unit (ICU) has been described, the number of publications in this important area appear relatively few, and PK data presented is not comprehensive. Known pathophysiological changes in critically ill patients result in altered drug PK when compared with non-critically ill patients. ClinPK Statement was recently developed to promote consistent reporting in PK studies, however, its applicability to ICU specific PK studies is unclear. In this systematic review, we assessed the overall ClinPK Statement compliance rate, determined the factors affecting compliance rate, graded the level of PK evidence and assessed the applicability of the ClinPK Statement to future ICU PK studies. Of the 33 included studies (n=2016), 22 (67%) were low evidence quality descriptive studies (Level 4). Included studies had a median compliance rate of 80% (IQR 66% to 86%) against the ClinPK Statement. Overall pooled compliance rate (78%, 95% CI 73% to 83%) was stable across time (P=0.38), with higher compliance rates found in studies fitting three compartments models (88%, P<0.01), two compartments models (83%, P<0.01) and one compartment models (77%, P=0.17) than studies fitting noncompartmental or unspecified models (69%) (P<0.01). Data unique to the interpretation of PK data in critically ill patients, such as illness severity (48%), organ dysfunction (36%) and renal replacement therapy use (32%), were infrequently reported. Discrepancy between the general compliance rate with ClinPK Statement and the under-reporting of ICU specific parameters suggests that the applicability of the ClinPK Statement to ICU PK studies may be limited in its current form.

Antimicrobial Doses in Continuous Renal Replacement Therapy: A Comparison of Dosing Strategies

Purpose. Drug dose recommendations are not well defined in patients undergoing continuous renal replacement therapy (CRRT) due to limited published data. Several guidelines and pharmacokinetic equations have been proposed as tools for CRRT drug dosing. Dose recommendations derived from these methods have yet to be compared or prospectively evaluated. Methods. A literature search of PubMed, Micromedex, and Embase was conducted for 40 drugs commonly used in the ICU to gather pharmacokinetic data acquired from patients with acute and chronic kidney disease as well as healthy volunteers. These data and that obtained from drug package inserts were gathered for use in three published CRRT drug dosing equations. Doses calculated for a model patient using each method were compared to doses suggested in a commonly used dosing text. Results. Full pharmacokinetic data was available for 18, 31, and 40 agents using acute kidney injury, end stage renal disease, and normal patient data, respectively. On average, calculated doses differed by 30% or more from the doses recommended by the renal dosing text for >50% of the medications. Conclusion. Wide variability in dose recommendations for patients undergoing CRRT exists when these equations are used. Alternate, validated dosing methods need to be developed for this at-risk patient population.

We Underdose Antibiotics in Patients on CRRT

Appropriate antibiotic dosing in critically ill, infected, patients receiving continuous renal replacement therapy (CRRT) is crucial to improve patient outcomes. Severe sepsis and septic shock result in changes in pharmacokinetic parameters, including increased volume of distribution, hypoalbuminemia, and changes in renal and nonrenal clearances. The lack of CRRT standardization, nonrecognition of how CRRT variability affects antibiotic removal, fear of antibiotic toxicity, and limited drug dosing resources all contribute to suboptimal antibiotic therapy. Even when antibiotic CRRT pharmacokinetic studies are available, they are often based on old CRRT methodologies that do not exist in contemporary CRRT practice, resulting in unhelpful/inaccurate dosing recommendations. Application of these older doses in Monte Carlo simulation studies reveals that many of the recommended dosing regimens will never attain pharmacodynamic targets. In this review, using cefepime as an example, we illustrate whether clinicians are likely to achieve pharmacokinetic/pharmacodynamic targets when the recommended dosing regimens are prescribed in this patient population. We encourage clinicians to aggressively dose antibiotics with large loading dose and higher maintenance doses to reach the targets.

Pharmacokinetics of cefoperazone/sulbactam in critically ill patients receiving continuous venovenous hemofiltration

PURPOSE

Cefoperazone/sulbactam (CFP/SUL) is a β-lactam/β-lactamase inhibitor combination with little data available for the development of effective dosing guidelines during continuous renal replacement therapy. This study aimed to investigate the pharmacokinetics (PK) of cefoperazone/sulbactam in critically ill patients on continuous venovenous hemofiltration (CVVH).

METHODS

A prospective, single-center, and open-label study was conducted. Critically ill patients receiving CVVH with 3 g cefoperazone/sulbactam (2.0/1.0 g) intravenously every 8 h were recruited. Serial blood and ultrafiltrate samples were paired collected for initial dose (occasion 1) and steady state (occasion 2). PK was assessed by non-compartmental analysis, and pharmacodynamics (PD) was evaluated by the percent of time for which drug concentrations exceed the minimum inhibitory concentration (%T >MIC).

RESULTS

Total fourteen patients were enrolled. Volume of distribution at steady state (V ss) of cefoperazone and sulbactam for initial doses (20.8 ± and 28.4 L, respectively) increased significantly compared with those in healthy volunteers (P = 0.009 for CFP, P = 0.030 for SUL). Both cefoperazone and sulbactam showed significantly lower total clearance (CLt) (46.2 and 117.6 mL/min, respectively) compared with healthy volunteers (P = 0.000 for CFP, P = 0.017 for SUL). There is no significant difference in PK between occasion 1 and occasion 2 (P > 0.05). For occasion 1, mean CVVH clearance accounted for 34.3 and 33.9 % for CLt of cefoperazone and sulbactam, respectively. The minimum PD target of 60%T >MIC was achieved in seven of eight patients. For occasion 2, eight of nine patients achieved cefoperazone concentrations that were above the MIC for the entire dosing interval.

CONCLUSIONS

PK of cefoperazone/sulbactam was altered in critically ill patients undergoing CVVH. Therapeutic drug monitoring would be recommended to individualize the dose regimen.

SaMpling Antibiotics in Renal Replacement Therapy (SMARRT): an observational pharmacokinetic study in critically ill patients

Background

Optimal antibiotic dosing is key to maximising patient survival, and minimising the emergence of bacterial resistance. Evidence-based antibiotic dosing guidelines for critically ill patients receiving RRT are currently not available, as RRT techniques and settings vary greatly between ICUs and even individual patients. We aim to develop a robust, evidence-based antibiotic dosing guideline for critically ill patients receiving various forms of RRT. We further aim to observe whether therapeutic antibiotic concentrations are associated with reduced 28-day mortality.

Methods/Design

We designed a multi-national, observational pharmacokinetic study in critically ill patients requiring RRT. The study antibiotics will be vancomycin, linezolid, piperacillin/tazobactam and meropenem. Pharmacokinetic sampling of each patient’s blood, RRT effluent and urine will take place during two separate dosing intervals. In addition, a comprehensive data set, which includes the patients’ demographic and clinical parameters, as well as modality, technique and settings of RRT, will be collected. Pharmacokinetic data will be analysed using a population pharmacokinetic approach to identify covariates associated with changes in pharmacokinetic parameters in critically ill patients with AKI who are undergoing RRT for the five commonly prescribed antibiotics.

Discussion

Using the comprehensive data set collected, the pharmacokinetic profile of the five antibiotics will be constructed, including identification of RRT and other factors indicative of the need for altered antibiotic dosing requirements. This will enable us to develop a dosing guideline for each individual antibiotic that is likely to be relevant to any critically ill patient with acute kidney injury receiving any of the included forms of RRT.

Trial registration

Australian New Zealand Clinical Trial Registry (ACTRN12613000241730) registered 28 February 2013

Reporting Guidelines for Clinical Pharmacokinetic Studies: The ClinPK Statement

BACKGROUND AND OBJECTIVE

Transparent reporting of all research is essential for assessing the validity of any study. Reporting guidelines are available and endorsed for many types of research but are lacking for clinical pharmacokinetic studies. Such tools promote the consistent reporting of a minimal set of information for end users, and facilitate knowledge translation of research. The objective of this study was to create a guideline to assist in the transparent and complete reporting of clinical pharmacokinetic studies.

METHODS

Preliminary content to be considered was identified from a systematic search of the literature and regulatory documents. Stakeholders were identified to participate in a modified Delphi exercise and a virtual meeting to generate consensus for items considered essential in the reporting of clinical pharmacokinetic studies. The proposed checklist was pilot tested on 100 recently published clinical pharmacokinetic studies. Overall and itemized compliance with the proposed guidance was determined for each study.

RESULTS

Sixty-eight stakeholders from nine countries consented to participate. Four rounds of a modified Delphi survey and a series of small virtual meetings were required to generate consensus for a 24-item checklist considered to be essential to the reporting of clinical pharmacokinetic studies. When applied to the 100 most recently published clinical pharmacokinetic studies, 45 were determined to be compliant with at least 80 % of the checklist items. Explanatory text was prepared using examples of compliant reporting from these and other relevant studies.

CONCLUSIONS

The reader's ability to judge the validity of pharmacokinetic research can be greatly compromised by the incomplete reporting of study information. Using consensus methods, we have developed a tool to guide transparent and accurate reporting of clinical pharmacokinetic studies. Endorsement and implementation of these guidelines by researchers, clinicians and journals would promote more consistent reporting of these studies and allow for better assessment of utility for clinical applications.

Piperacillin population pharmacokinetics in critically ill patients with multiple organ dysfunction syndrome receiving continuous venovenous haemodiafiltration: effect of type of dialysis membrane on dosing requirements

OBJECTIVES

This multicentre study aimed to describe the pharmacokinetics (PK) of piperacillin in critically ill patients with multiple organ dysfunction syndrome (MODS) receiving continuous venovenous haemodiafiltration (CVVHDF), to identify the sources of PK variability and evaluate different dosing regimens to develop recommendations based on clinical parameters.

PATIENTS AND METHODS

Nineteen patients with MODS and CVVHDF receiving piperacillin/tazobactam were enrolled from three tertiary hospitals (95 plasma samples). Population PK modelling and Monte Carlo simulations were performed using NONMEM v7.3(®).

RESULTS

Patients' median age was 70 years (range 39-82), median weight was 80 kg (45-129), median APACHE II score at admission was 21 (13-33) and median SOFA score on the day of study was 11 (8-21). The final population PK model was characterized by CL (L/h) = 6.11 * [weight (kg)/80](1.39) * CLMEMB. If membrane = 1.5 m(2) AN69ST, CLMEMB = 1; if membrane = 0.9 m(2) AN69, CLMEMB = 0.51. Monte Carlo simulations showed that: (i) to maintain unbound piperacillin concentrations above the MIC for the bacteria for 100% of dosing interval T (100%fuT>MIC), patients receiving CVVHDF with 1.5 m(2) AN69ST membranes required doses of 4000 mg q8h for the treatment of bacteria with a susceptibility to piperacillin close to the clinical breakpoint (MIC = 8-16 mg/L) (2000 mg q8h was sufficient for patients with CVVHDF using 0.9 m(2) AN69 membranes); and (ii) for the treatment of bacteria with high susceptibility to piperacillin (MIC <4 mg/L) or for the attainment of a more traditional pharmacodynamic target (50%fuT>MIC), 2000 mg q8h sufficed regardless of type of membrane and body weight.

CONCLUSIONS

Our results suggest that type of membrane and body weight should be considered for piperacillin dose titration in critically ill patients with MODS and CVVHDF requirement.

[Antibiotic dosing for renal function disorders and continuous renal replacement therapy]

For patients with acute kidney injury (AKI) and continuous renal replacement therapy, it is essential that the dosing of antibiotics is adequately adjusted in order to achieve an effective drug level above the minimum inhibition concentration but avoiding toxic side effects. In the selection of substances, preference should be given to antibiotics with a broad therapeutic spectrum, low incidence of side effects and, as far as possible, extrarenal elimination. Determination of serum levels should always be carried out, when this is possible. In any case, a sufficiently high loading dose should be included. An accurate as possible estimation of residual renal function and calculation of the mechanical clearance allows determination of the necessary maintenance dosage, which is acceptably accurate for clinical needs. Recent studies have shown that under modern continuous renal replacement therapy, the extent of elimination of antibiotics is regularly underestimated so that nowadays, the risk of antibiotic underdosing is higher than toxicity due to overdosing.

Meropenem population pharmacokinetics in critically ill patients with septic shock and continuous renal replacement therapy: influence of residual diuresis on dose requirements

Meropenem dosing in critically ill patients with septic shock and continuous renal replacement therapy (CRRT) is complex, with the recommended maintenance doses being 500 mg to 1,000 mg every 8 h (q8h) to every 12 h. This multicenter study aimed to describe the pharmacokinetics (PKs) of meropenem in this population to identify the sources of PK variability and to evaluate different dosing regimens to develop recommendations based on clinical parameters. Thirty patients with septic shock and CRRT receiving meropenem were enrolled (153 plasma samples were tested). A population PK model was developed with data from 24 patients and subsequently validated with data from 6 patients using NONMEM software (v.7.3). The final model was characterized by CL = 3.68 + 0.22 · (residual diuresis/100) and V = 33.00 · (weight/73)(2.07), where CL is total body clearance (in liters per hour), residual diuresis is the volume of residual diuresis (in milliliters per 24 h), and V is the apparent volume of distribution (in liters). CRRT intensity was not identified to be a CL modifier. Monte Carlo simulations showed that to maintain concentrations of the unbound fraction (fu ) of drug above the MIC of the bacteria for 40% of dosing interval T (referred to as 40% of the ƒ uT >MIC), a meropenem dose of 500 mg q8h as a bolus over 30 min would be sufficient regardless of the residual diuresis. If 100% of the ƒ uT >MIC was chosen as the target, oligoanuric patients would require 500 mg q8h as a bolus over 30 min for the treatment of susceptible bacteria (MIC < 2 mg/liter), while patients with preserved diuresis would require the same dose given as an infusion over 3 h. If bacteria with MICs close to the resistance breakpoint (2 to 4 mg/liter) were to be treated with meropenem, a dose of 500 mg every 6 h would be necessary: a bolus over 30 min for oligoanuric patients and an infusion over 3 h for patients with preserved diuresis. Our results suggest that residual diuresis may be an easy and inexpensive tool to help with titration of the meropenem dose and infusion time in this challenging population.

A multicenter study on the effect of continuous hemodiafiltration intensity on antibiotic pharmacokinetics

Introduction

Continuous renal replacement therapy (CRRT) may alter antibiotic pharmacokinetics and increase the risk of incorrect dosing. In a nested cohort within a large randomized controlled trial, we assessed the effect of higher (40 mL/kg per hour) and lower (25 mL/kg per hour) intensity CRRT on antibiotic pharmacokinetics.

Methods

We collected serial blood samples to measure ciprofloxacin, meropenem, piperacillin-tazobactam, and vancomycin levels. We calculated extracorporeal clearance (CL), systemic CL, and volume of distribution (Vd) by non-linear mixed-effects modelling. We assessed the influence of CRRT intensity and other patient factors on antibiotic pharmacokinetics.

Results

We studied 24 patients who provided 179 pairs of samples. Extracorporeal CL increased with higher-intensity CRRT but the increase was significant for vancomycin only (mean 28 versus 22 mL/minute; P = 0.0003). At any given prescribed CRRT effluent rate, extracorporeal CL of individual antibiotics varied widely, and the effluent-to-plasma concentration ratio decreased with increasing effluent flow. Overall, systemic CL varied to a greater extent than Vd, particularly for meropenem, piperacillin, and tazobactam, and large intra-individual differences were also observed. CRRT dose did not influence overall (systemic) CL, Vd, or half-life. The proportion of systemic CL due to CRRT varied widely and was high in some cases.

Conclusions

In patients receiving CRRT, there is great variability in antibiotic pharmacokinetics, which complicates an empiric approach to dosing and suggests the need for therapeutic drug monitoring. More research is required to investigate the apparent relative decrease in clearance at higher CRRT effluent rates.

Trial registration

ClinicalTrials.gov NCT00221013. Registered 14 September 2005.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0818-8) contains supplementary material, which is available to authorized users.

Comparison of intermittent and continuous extracorporeal treatments for the enhanced elimination of dabigatran

CONTEXT

Severe bleeding associated with dabigatran frequently requires intensive care management. An antidote is currently unavailable and data reporting the effect of dialysis on elimination of dabigatran are encouraging, but limited. Objective. To report the effect of intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT) at enhancing elimination of dabigatran.

MATERIALS AND METHODS

Patients were identified by existing collaborative networks. Pre-filter dabigatran plasma concentrations were measured in all patients, and in dialysate of three patients.

RESULTS

Seven patients received dialysis, five with active bleeding and two requiring emergent surgery. Five received IHD and two received CRRT. The plasma elimination half-life of dabigatran was 1.5-4.9 h during IHD, and 14.0-27.5 h during CRRT. Mean dabigatran plasma clearance during IHD was 85-169 mL/min in three patients. Time to obtain a subtherapeutic dabigatran concentration depended on the initial concentration, being 8-18 h for IHD in three patients while 4 h was insufficient in a supratherapeutic case. A 38% rebound in dabigatran levels occurred after one case during IHD, and thrombin time increased after IHD in another, but not after 144 h CRRT or 17 h IHD in two others; data were incomplete in three cases. The amount removed during IHD was proportional to the pre-IHD concentration and clearance, but was consistently low at 3.3-17.4 mg in three patients where this was determined. Moderate bleeding occurred while obtaining vascular access in one patient. Two patients died from intracerebral bleeding, and the influence of treatments could not be determined in these cases.

DISCUSSION AND CONCLUSIONS

IHD enhanced elimination of dabigatran more efficiently than CRRT, but their net effect remains poorly defined. Dialysis decisions, including modality and duration, must be individualized based on a risk-benefit assessment.

Anti-infective drugs during continuous hemodialysis - using the bench to learn what to do at the bedside

PURPOSE

The main objective of this study was to investigate the clearance of 11 selected anti-infectives in an in vitro model of continuous veno-venous hemodialysis (CVVHD), in order to suggest rational dosing strategies for clinical practice.

METHODS

Ceftazidime, ciprofloxacin, flucloxacillin, gentamicin, linezolid, meropenem, metronidazole, piperacillin, rifampicin, vancomycin and voriconazole were studied in two different solvents (sodium chloride 0.9% and HSA 5%) using a multifiltrate dialysis device by Fresenius Medical Care (Bad Homburg, Germany). For each solution, prefilter, postfilter, and dialysate samples were drawn simultaneously during one hour of dialysis and were assayed.

RESULTS

The clearance of all drugs except rifampicin in sodium chloride 0.9% was comparable (mean 1.76 ± 0.11 l/h). The clearance of these agents in human serum albumin solution 5% was reduced by between 5.3% and 72.2%. The unbound drug fraction correlated with a lower clearance in HSA 5% (Pearson correlation coefficient r = 0.933; p = 0.00008). No correlation between clearance in HSA 5% and the drugs' molecular weight was found (Pearson correlation coefficient r = 0.388; p = 0.268). Rifampicin was detected to bind to the surface of the polysulfone filter used. Dialysis clearance of ceftazidime, gentamicin, linezolid, meropenem, metronidazole, piperacillin and vancomycin during CVVHD accounted for over 25% of the total body clearance of population pharmacokinetic data for renally impaired patients.

CONCLUSIONS

The results from this study highlight that dose adaptations are needed for most of the drugs under investigation for patients undergoing CVVHD. In combination with polysulfone filters, rifampicin should be used with care in this setting.

The doripenem serum concentrations in intensive care patients suffering from acute kidney injury, sepsis, and multi organ dysfunction syndrome undergoing continuous renal replacement therapy slow low-efficiency dialysis

Doripenem is a novel wide-spectrum antibiotic, and a derivate of carbapenems. It is an ideal antibiotic for treatment of serious nosocomial infections and severe sepsis for its exceptionally high efficiency and broad antibacterial spectrum of action. Doripenem is eliminated mainly by the kidneys. In cases of acute kidney injury, dosing of doripenem depends on creatinine clearance and requires adjustments. Doripenem is eliminated during hemodialysis because its molecular weight is 300–400 Da. The aim of this study was to establish the impact of continuous renal replacement therapy (CRRT) slow low-efficiency dialysis (SLED) on doripenem serum concentrations in a population of intensive-therapy patients with life-threatening infections and severe sepsis. Ten patients were enrolled in this observational study. Twelve blood samples were collected during the first administration of doripenem in a 1-hour continuous infusion while CRRT SLED was provided. Fluid chromatography was used for measurement of the concentration of doripenem in serum. In all collected samples, concentration of doripenem was above the minimum inhibition concentration of this antibiotic. Based on these results, we can draw the conclusion that doripenem concentration is above the minimum inhibition concentration throughout all of CRRT. The dosing pattern proposed by the manufacturer can be used in patients receiving CRRT SLED without necessary modifications.

Pharmacokinetic assessment in patients receiving continuous RRT: perspectives from the Kidney Health Initiative

The effect of AKI and modern continuous RRT (CRRT) methods on drug disposition (pharmacokinetics) and response has been poorly studied. Pharmaceutical manufacturers have little incentive to perform pharmacokinetic studies in patients undergoing CRRT because such studies are neither recommended in existing US Food and Drug Administration (FDA) guidance documents nor required for new drug approval. Action is urgently needed to address the knowledge deficit. The Kidney Health Initiative has assembled a work group composed of clinicians and scientists representing academia, the FDA, and the pharmaceutical and dialysis industries with expertise related to pharmacokinetics, AKI, and/or CRRT. The work group critically evaluated key considerations in the assessment of pharmacokinetics and drug dosing in CRRT, practical constraints related to conducting pharmacokinetic studies in critically ill patients, and the generalizability of observations made in the context of specific CRRT prescriptions and specific patient populations in order to identify efficient study designs capable of addressing the knowledge deficit without impeding drug development. Considerations for the standardized assessment of pharmacokinetics and development of corresponding drug dosing recommendations in critically ill patients with AKI receiving CRRT are proposed.

Approaches for dosage individualisation in critically ill patients

INTRODUCTION

Pharmacokinetic variability in critically ill patients is the result of the overlapping of multiple pathophysiological and clinical factors. Unpredictable exposure from standard dosage regimens may influence the outcome of treatment. Therefore, strategies for dosage individualisation are recommended in this setting.

AREAS COVERED

The authors focus on several approaches for dosage individualisation that have been developed, ranging from the well-established therapeutic drug monitoring (TDM) up to the innovative application of pharmacogenomics criteria. Furthermore, the authors summarise the specific population pharmacokinetic models for different drugs developed for critically ill patients to improve the initial dosage selection and the Bayesian forecasting of serum concentrations. The authors also consider the use of Monte Carlo simulation for the selection of dosage strategies.

EXPERT OPINION

Pharmacokinetic/pharmacodynamics (PK/PD) modelling and dosage individualisation methods based on mathematical and statistical criteria will contribute in improving pharmacologic treatment in critically ill patients. Moreover, substantial effort will be necessary to integrate pharmacogenomics criteria into critical care practice. The lack of availability of target biomarkers for dosage adjustment emphasizes the value of TDM which allows a large part of treatment outcome variability to be controlled.

Pharmacokinetics of caspofungin in critically ill patients on continuous renal replacement therapy

Caspofungin pharmacokinetics was assessed in 27 critically ill patients, including 7 on continuous venovenous hemofiltration (CVVH), 8 on continuous venovenous hemodialysis (CVVHD), and 13 not requiring continuous renal replacement therapy (CRRT). Caspofungin exposure during CRRT was very similar to that of the control group and comparable to that in healthy volunteers. Caspofungin clearance by CRRT was very low. Therefore, the standard dosage of caspofungin is probably adequate for critically ill patients undergoing CVVH or CVVHD.

Pharmacokinetics of meprobamate in overdose treated with continuous venovenous hemodiafiltration (CVVHDF)

We report a case of massive suicidal overdose of meprobamate leading to cardiovascular collapse, respiratory failure, and severe central nervous system depression. We observed first-order elimination kinetics despite significant overdose, and demonstrated effectiveness of continuous venovenous hemodiafiltration (CVVHDF) for extracorporeal removal of meprobamate in this patient. Total body clearance was calculated to be 87 mL/minute, with 64 mL/minute (74%) due to CVVHDF. CVVHDF was stopped after 36 hours, and the patient made an uneventful recovery.

Presence and accuracy of drug dosage recommendations for continuous renal replacement therapy in tertiary drug information references

BACKGROUND

Clinicians commonly rely on tertiary drug information references to guide drug dosages for patients who are receiving continuous renal replacement therapy (CRRT). It is unknown whether the dosage recommendations in these frequently used references reflect the most current evidence.

OBJECTIVE

To determine the presence and accuracy of drug dosage recommendations for patients undergoing CRRT in 4 drug information references.

METHODS

Medications commonly prescribed during CRRT were identified from an institutional medication inventory database, and evidence-based dosage recommendations for this setting were developed from the primary and secondary literature. The American Hospital Formulary System-Drug Information (AHFS-DI), Micromedex 2.0 (specifically the DRUGDEX and Martindale databases), and the 5th edition of Drug Prescribing in Renal Failure (DPRF5) were assessed for the presence of drug dosage recommendations in the CRRT setting. The dosage recommendations in these tertiary references were compared with the recommendations derived from the primary and secondary literature to determine concordance.

RESULTS

Evidence-based drug dosage recommendations were developed for 33 medications administered in patients undergoing CRRT. The AHFS-DI provided no dosage recommendations specific to CRRT, whereas the DPRF5 provided recommendations for 27 (82%) of the medications and the Micromedex 2.0 application for 20 (61%) (13 [39%] in the DRUGDEX database and 16 [48%] in the Martindale database, with 9 medications covered by both). The dosage recommendations were in concordance with evidence-based recommendations for 12 (92%) of the 13 medications in the DRUGDEX database, 26 (96%) of the 27 in the DPRF5, and all 16 (100%) of those in the Martindale database.

CONCLUSIONS

One prominent tertiary drug information resource provided no drug dosage recommendations for patients undergoing CRRT. However, 2 of the databases in an Internet-based medical information application and the latest edition of a renal specialty drug information resource provided recommendations for a majority of the medications investigated. Most dosage recommendations were similar to those derived from the primary and secondary literature. The most recent edition of the DPRF is the preferred source of information when prescribing dosage regimens for patients receiving CRRT.

Therapeutic drug monitoring of antimicrobials

Optimizing the prescription of antimicrobials is required to improve clinical outcome from infections and to reduce the development of antimicrobial resistance. One such method to improve antimicrobial dosing in individual patients is through application of therapeutic drug monitoring (TDM). The aim of this manuscript is to review the place of TDM in the dosing of antimicrobial agents, specifically the importance of pharmacokinetics (PK) and pharmacodynamics (PD) to define the antimicrobial exposures necessary for maximizing killing or inhibition of bacterial growth. In this context, there are robust data for some antimicrobials, including the ratio of a PK parameter (e.g. peak concentration) to the minimal inhibitory concentration of the bacteria associated with maximal antimicrobial effect. Blood sampling of an individual patient can then further define the relevant PK parameter value in that patient and, if necessary, antimicrobial dosing can be adjusted to enable achievement of the target PK/PD ratio. To date, the clinical outcome benefits of a systematic TDM programme for antimicrobials have only been demonstrated for aminoglycosides, although the decreasing susceptibility of bacteria to available antimicrobials and the increasing costs of pharmaceuticals, as well as emerging data on pharmacokinetic variability, suggest that benefits are likely.