Clinical review: Drug metabolism and nonrenal clearance in acute kidney injury

Pharmacokinetics of Opioid Infusions in the Adult Intensive Care Unit Setting-A Systematic Review

INTRODUCTION

Pharmacokinetics (PKs) of drugs are often altered in the intensive care unit (ICU). Opioids are often used in the ICU, particularly as continuous infusions, and their characteristics lead them to undergo PK alterations. We conducted a systematic review to assess the PK of opioid infusions in the ICU.

METHODS

Embase, MEDLINE, PubMed, CINAHL, and Evidence-Based Medicine Reviews (EBMR) were searched from inception to March 2024. Studies were included if they evaluated PKs of opioid infusions in adult patients in the ICU. Two reviewers independently selected and extracted data.

RESULTS

Out of the 1040 records screened, 17 studies were included. Five studies were conducted on fentanyl, seven on morphine, one on hydromorphone, two on remifentanil, two on alfentanil, and one on sufentanil. Most studies where observational studies or case series. The mean age was 56 years old. Duration of the infusion varied between 3 h and 20 days. PKs of fentanyl, sufentanil, and hydromorphone were significantly impaired, whereas the PKs of morphine, alfentanil, and remifentanil were impaired to a lesser degree. The PK parameter that was most affected by critical illness was the half-life (T½).

CONCLUSIONS

To counter these PK alterations, new therapeutic avenues must be further explored in the ICU to individualize opioid infusions.

Validating Low-Dose Iohexol as a Marker for Glomerular Filtration Rate by In Vitro and In Vivo Studies

Clearance of an intravenous iohexol dose of 3235 mg is used to assess glomerular filtration rate (GFR), although systematic assessment of its pharmacokinetic (PK) properties is incomplete. The objectives of the present investigations were (i) to assess potential interactions of iohexol with important drug transporters, and (ii) whether a 259 mg dose could replace the current standard dose. In vitro, we evaluated whether iohexol inhibits or is transported by renal transporters (hOAT1/3, hOCT2, and hMATE1/2K) or other transporters (hOATP1B1/3, hOCT1, and hMDR1) using cell-based and vesicle-based systems. In vivo, we conducted a clinical trial with 12 volunteers with the administration of single intravenous doses of 3235 mg ("reference") and 259 mg ("test") using a changeover design. Plasma and urine samples were collected up to 24 h postdose. We assessed the dose linearity of iohexol pharmacokinetics using the standard bioequivalence approach and conducted a population PK analysis to characterize its profile. Our in vitro findings indicate that iohexol is neither a substrate nor a significant inhibitor of the transporters, suggesting it is unlikely to participate in transporter-mediated drug-drug interactions in vivo. In the clinical trial, the test/reference ratio for plasma clearance, calculated as dose divided by the area under the plasma concentration-time curve, was 1.01 (90% confidence interval 0.968-1.05), confirming dose linearity. Population PK analysis further supported these results, showing no significant effect of dose on renal clearance and negligible nonrenal clearance of iohexol. Low-dose iohexol is a suitable marker for precise GFR measurement, even when coadministered with other drugs.

Acute kidney injury is associated with liver-related outcomes in patients with hepatitis B virus infection: a retrospective cohort study

BACKGROUND

The effects of acute kidney injury (AKI) on liver-related outcomes in patients with hepatitis B virus (HBV) infection remain unclear. The study aimed to evaluate the association between AKI with liver-related mortality and complications in patients with HBV infection.

METHODS

The multicenter, retrospective cohort study included Chinese adults with HBV infection from 24 regional central hospitals between January 2000 and December 2022. AKI was defined as a ≥ 26.5 μmol/l increase in serum creatinine concentration within 48 h, or a ≥ 50% increase over the baseline within 7 days. The primary outcome was post-discharge liver-related mortality, while the secondary outcome was a composite of new-onset liver cirrhosis and hepatocellular carcinoma. Cox proportional hazard model was employed for analyses.

RESULTS

Of the 86,204 inpatients with HBV infection and without liver cancer or cirrhosis at baseline, 4407(5.1%) patients experienced AKI. During a mean follow-up of 4.6 ± 2.4 years, 334 (0.4%) patients died of liver-related events. After adjustment, AKI during hospitalization was significantly associated with a higher risk of liver-related mortality after discharge (adjusted hazard ratio (HR), 1.78; 95% confidence intervals (CI), 1.26-2.51, P = 0.001), especially in those with severe AKI. Similarly, AKI was associated with a higher risk of cirrhosis or new-onset hepatocellular carcinoma (adjusted HR, 1.33; 95%CI, 1.10-1.60, P = 0.004). The association between AKI and liver-related outcomes remained consistent across different subgroups.

CONCLUSIONS

AKI during hospitalization was associated with substantial increased risk of liver-related mortality and incident liver-related complication. Our findings highlight the importance of monitoring AKI in patients with HBV infection for tailoring personalized treatments.

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.

Clinical guidance for unfractionated heparin dosing and monitoring in critically ill patients

INTRODUCTION

Unfractionated heparin is a widely used anticoagulant in critically ill patients. It has a well-established safety profile and remains an attractive option for clinicians due to its short half-life and reversibility. Heparin has a unique pharmacokinetic profile, which contributes to significant inter-patient and intra-patient variability in effect. The variability in anticoagulant effect combined with heparin's short half-life mean close monitoring is required for clinical efficacy and preventing adverse effects. To optimize heparin use in critically ill patients, effective monitoring assays and dose adjustment strategies are needed.

AREAS COVERED

This paper explores the use of heparin as an anticoagulant and optimal approaches to monitoring in critically ill patients.

EXPERT OPINION

Conventional monitoring assays for heparin dosing have significant limitations. Emerging data appear to favor using anti-Xa assay monitoring for heparin anticoagulation, which many centers have successfully adopted as the standard. The anti-Xa assay appears have important benefits relative to the aPTT for heparin monitoring in critically ill patients, and should be considered for broader use.

Pharmacokinetic Research in Pediatric Extracorporeal Therapies: Current State and Future Directions

Extracorporeal life support (ECLS), including extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT), are life-saving therapies for critically ill children. Despite this, these modalities carry frustratingly high mortality rates. One driver of mortality may be altered drug disposition due to a combination of underlying illness, patient-circuit interactions, and drug-circuit interactions. Children receiving ECMO and/or CRRT routinely receive 20 or more drugs, and data supporting optimal dosing is lacking for most of these medications. The Pediatric Paracorporeal and Extracorporeal Therapies Summit (PPETS) gathered an international group of experts in the fields of ECMO, CRRT, and other ECLS modalities to discuss the current state of these therapies, disseminate innovative support strategies, share clinical experiences, and foster future collaborations. Here, we summarize the conclusions of PPETS and put forward a pathway to optimize pharmacokinetic (PK) research in this population. We must prioritize specific medications for in-depth study to improve drug use in ECLS and patient outcomes. Based on frequency of use, potential for adverse outcomes if dosed inappropriately, and lack of existing PK data, a list of high priority drugs was compiled for future research. Researchers must additionally reconsider study designs, emphasizing pooling of resources through multi-center studies and the use of innovative PK modeling techniques. Finally, the integration of validated PK models into clinical practice must be streamlined to deliver optimal medication use at the bedside. Focusing on the proposed list of highlighted medications and key methodological considerations will maximize the impact of future research.

Acute kidney injury interacts with VKORC1 genotype on initiative warfarin dose among heart surgery recipients: a real-world research

Patients who receive heart valve surgery need anticoagulation prophylaxis to reduce the risk of thrombosis. Warfarin often is a choice but its dosage varies due to gene and clinical factors. We aim to study, among them, if there is an interaction between acute kidney injury and two gene polymorphisms from this study. We extracted data of heart valve surgery recipients from the electronic health record (EHR) system of a medical center. The primary outcome is about the average daily dose of warfarin, measured as an additive interaction effect (INTadd) between acute kidney injury (AKI) and warfarin-related gene polymorphisms. The confounders, including age, sex, body surface area (BSA), comorbidities (i.e., atrial fibrillation [AF], hypertension [HTN], congestive heart failure [CHF]), serum albumin level, warfarin-relevant gene polymorphism (i.e., CYP2C9, VKORC1), prosthetic valve type (i.e., metal, bio), and warfarin history were controlled via a multivariate-linear regression model. The study included 200 patients, among whom 108 (54.00%) are female. Further, the mean age is 54.45 years, 31 (15.50%) have CHF, and 40 (20.00%) patients were prescribed concomitant amiodarone, which potentially overlays with the warfarin prophylaxis period. During the follow-up, AKI occurred in 30 (15.00%) patients. VKORC1 mutation (1639G>A) occurred in 25 (12.50%) patients and CYPC29 *2 or *3 mutations presented in 20 patients (10.00%). We found a significant additive interaction effect between AKI and VKORC1 (- 1.17, 95% CI - 1.82 to - 0.53, p = 0.0004). This result suggests it is probable that there is an interaction between acute kidney injury and the VKORC1 polymorphism for the warfarin dose during the initial period of anticoagulation prophylaxis.

Piperacillin-tazobactam dosing in anuric acute kidney injury patients receiving continuous renal replacement therapy

INTRODUCTION

To determine appropriate dosing of piperacillin-tazobactam in critically ill patients receiving continuous renal replacement therapy (CRRT).

METHODS

The databases of PubMed, Embase, and ScienceDirect were searched. We used the Medical Subject Headings of "piperacillin-tazobactam," "CRRT," and "pharmacokinetics" or related terms or synonym to identify the studies for reviews. A one-compartment pharmacokinetic model was conducted to predict piperacillin levels for the initial 48 h of therapy. The pharmacodynamic target was 50% of free drug level above the minimum inhibitory concentration (MIC) and 4 times of the MIC. The dose that achieved at least 90% of the probability of target attainment was defined as an optimal dose.

RESULTS

Our simulation study reveals that the dosing regimen of piperacillin-tazobactam 12 g/day is appropriate for treating Pseudomonal infection with KDIGO recommended effluent rate of 25-35 mL/kg/h. The MIC values of each setting were an important factor to design piperacillin-tazobactam dosing regimens.

CONCLUSION

The Monte Carlo simulation can be a useful tool to evaluate drug dosing in critically ill acute kidney injury patients receiving CRRT when limited pharmacokinetic data are a concern. Clinical validation of these results is needed.

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.

The Pitfall of Over-Sedation During Recovery From Acute Kidney Injury

A 14-year-old boy with movement disorder and epilepsy developed status dystonicus leading to rhabdomyolysis and subsequent acute kidney injury requiring continuous renal replacement therapy (CRRT). He was given multiple intravenous sedatives and analgesics to control his dystonia and dyskinesia. 8 days after admission, his condition had improved and a trial termination of CRRT was carried out. The sedatives and analgesics were switched to oral diazepam, morphine, clonidine, and chloral hydrate. However, his renal function did not recover fully. There was rising trend of serum creatinine level with evolving hyperphosphatemia and metabolic acidosis. He also gradually developed hypoventilation, hypercapnia and pinpoint pupils after weaning CRRT. The clinical impression was over-sedation resulting in hypoventilation and respiratory failure, contributed by the deteriorating renal function. Non-invasive ventilatory support was then started and CRRT was resumed. His condition improved over the next 24 hours. Dexmedetomidine infusion was used during CRRT and he slowly required stepping up of sedatives again. A separate set of dosage for all his oral sedative agents was prepared for his subsequent CRRT weaning challenge and no more over-sedative episode was then encountered. Our case illustrated that patients at recovery phase of AKI are susceptible to medication overdose, especially during the period of CRRT weaning. Sedatives and analgesics including morphine and benzodiazepines should be used with caution during this period and alternatives may need to be considered. Advanced planning of medication dosage adjustment is advised to reduce the risk of medication overdose.

Pharmacokinetic Alterations Associated with Critical Illness

Haemodynamic, metabolic, and biochemical derangements in critically ill patients affect drug pharmacokinetics and pharmacodynamics making dose optimisation particularly challenging. Appropriate therapeutic dosing depends on the knowledge of the physiologic changes caused by the patient's comorbidities, underlying disease, resuscitation strategies, and polypharmacy. Critical illness will result in altered drug protein binding, ionisation, and volume of distribution; it will also decrease oral drug absorption, intestinal and hepatic metabolism, and renal clearance. In contrast, the resuscitation strategies and the use of vasoactive drugs may oppose these effects by leading to a hyperdynamic state that will increase blood flow towards the major organs including the brain, heart, kidneys, and liver, with the subsequent increase of drug hepatic metabolism and renal excretion. Metabolism is the main mechanism for drug clearance and is one of the main pharmacokinetic processes affected; it is influenced by patient-specific factors, such as comorbidities and genetics; therapeutic-specific factors, including drug characteristics and interactions; and disease-specific factors, like organ dysfunction. Moreover, organ support such as mechanical ventilation, renal replacement therapy, and extracorporeal membrane oxygenation may contribute to both inter- and intra-patient variability of drug pharmacokinetics. The combination of these competing factors makes it difficult to predict drug response in critically ill patients. Pharmacotherapy targeted to therapeutic goals and therapeutic drug monitoring is currently the best option for the safe care of the critically ill. The aim of this paper is to review the alterations in drug pharmacokinetics associated with critical illness and to summarise the available evidence.

Crosstalk between kidney and liver in non-alcoholic fatty liver disease: mechanisms and therapeutic approaches

Liver and kidney are vital organs that maintain homeostasis and injury to either of them triggers pathogenic pathways affecting the other. For example, non-alcoholic fatty liver disease (NAFLD) promotes the progression of chronic kidney disease (CKD), vice versa acute kidney injury (AKI) endorses the induction and progression of liver dysfunction. Progress in clinical and basic research suggest a role of excessive fructose intake, insulin resistance, inflammatory cytokines production, activation of the renin-angiotensin system, redox imbalance, and their impact on epigenetic regulation of gene expression in this context. Recent developments in experimental and clinical research have identified several biochemical and molecular pathways for AKI-liver interaction, including altered liver enzymes profile, metabolic acidosis, oxidative stress, activation of inflammatory and regulated cell death pathways. This review focuses on the current preclinical and clinical findings on kidney-liver crosstalk in NAFLD-CKD and AKI-liver dysfunction settings and highlights potential molecular mechanisms and therapeutic targets.

Antimicrobial safety considerations in critically ill patients: part I: focused on acute kidney injury

INTRODUCTION

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

AREAS COVERED

In the current article, we searched PubMed, Scopus, and Google Scholar for estimating renal function in acute kidney injury, nephrotoxicity of commonly used antibiotics, and nephrotoxin stewardship in intensive care units.

EXPERT OPINION

Early estimation of kidney function with an accurate method may be helpful to optimize antimicrobial treatment in critically ill patients. Different antibiotic dosing regimens may be required for patients with acute kidney injury. In many low-resource settings, therapeutic drug monitoring is not available for antibiotics. Acute kidney injury may influence treatment effectiveness and patient outcome.

Metabolomic profiling demonstrates evidence for kidney and urine metabolic dysregulation in a piglet model of cardiac surgery-induced acute kidney injury

Acute kidney injury (AKI) is a common cause of morbidity after congenital heart disease surgery. Progress on diagnosis and therapy remains limited, however, in part due to poor mechanistic understanding and a lack of relevant translational models. Metabolomic approaches could help identify novel mechanisms of injury and potential therapeutic targets. In the present study, we used a piglet model of cardiopulmonary bypass with deep hypothermic circulatory arrest (CPB/DHCA) and targeted metabolic profiling of kidney tissue, urine, and serum to evaluate metabolic changes specific to animals with histological acute kidney injury. CPB/DHCA animals with acute kidney injury were compared with those without acute kidney injury and mechanically ventilated controls. Acute kidney injury occurred in 10 of 20 CPB/DHCA animals 4 h after CPB/DHCA and 0 of 7 control animals. Injured kidneys showed a distinct tissue metabolic profile compared with uninjured kidneys (R² = 0.93, Q² = 0.53), with evidence of dysregulated tryptophan and purine metabolism. Nine urine metabolites differed significantly in animals with acute kidney injury with a pattern suggestive of increased aerobic glycolysis. Dysregulated metabolites in kidney tissue and urine did not overlap. CPB/DHCA strongly affected the serum metabolic profile, with only one metabolite that differed significantly with acute kidney injury (pyroglutamic acid, a marker of oxidative stress). In conclusion, based on these findings, kidney tryptophan and purine metabolism are candidates for further mechanistic and therapeutic investigation. Urine biomarkers of aerobic glycolysis could help diagnose early acute kidney injury after CPB/DHCA and warrant further evaluation. The serum metabolites measured at this early time point did not strongly differentiate based on acute kidney injury.

NEW & NOTEWORTHY This project explored the metabolic underpinnings of postoperative acute kidney injury (AKI) following pediatric cardiac surgery in a translationally relevant large animal model of cardiopulmonary bypass with deep hypothermic circulatory arrest. Here, we present novel evidence for dysregulated tryptophan catabolism and purine catabolism in kidney tissue and increased urinary glycolysis intermediates in animals who developed histological AKI. These pathways represent potential diagnostic and therapeutic targets for postoperative AKI in this high-risk population.

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.

Pharmacokinetics of Commonly Used Medications in Children Receiving Continuous Renal Replacement Therapy: A Systematic Review of Current Literature

BACKGROUND AND OBJECTIVE

The use of continuous renal replacement therapy (CRRT) for renal support has increased substantially in critically ill children compared with intermittent modalities owing to its preferential effects on hemodynamic stability. With the expanding role of CRRT, the quantification of extracorporeal clearance and the effect on primary pharmacokinetic parameters is of the utmost importance. Within this review, we aimed to summarize the current state of the literature and compare published pharmacokinetic analyses of commonly used medications in children receiving CRRT to those who are not.

METHODS

A systematic search of the literature within electronic databases PubMed, EMBASE, Cochrane Library, and Web of Science was conducted. Published studies that were included contained relevant information on the use of commonly administered medications to children, from neonates to adolescents, receiving CRRT. Pharmacokinetic parameters that were analyzed included volume of distribution, total clearance, extracorporeal clearance, area under the curve, and elimination half-life. Information regarding CRRT circuit, flow rates, and membrane components was analyzed to investigate differences in pharmacokinetics between each modality.

RESULTS

Forty-five studies met the final inclusion criteria within this systematic review, totaling 833 pediatric patients, with 586 receiving CRRT. Antimicrobials were the most common pharmacological class represented within the literature, representing 81% (35/43) of studies analyzed. Children receiving CRRT largely had similar volume of distribution and total clearance to critically ill children not receiving CRRT, suggesting reno-protective dose adjustments may lead to subtherapeutic dosing regimens in these patients. Overall, there was a tendency for hydrophilic agents, with a low protein binding to undergo elevated total clearance in these children. However, results should be interpreted with caution because of the large variability amongst patient populations and heterogeneity with CRRT modalities, flow rates, and use of extracorporeal membrane oxygenation within studies. This review was able to identify that variation in solute removal, or CRRT modalities, properties (i.e., flow rates), and membrane composition, may have differing effects on the pharmacokinetics of commonly administered medications.

CONCLUSIONS

The current state of the literature regarding medications administered to children receiving CRRT largely focuses on antimicrobials. Significant gaps remain with other commonly used medications such as sedatives and analgesics. Overall reporting of patient clinical characteristics, CRRT settings, and circuit composition was poor, with only 10% of articles including all relevant information to assess the impact of CRRT on total clearance. Changes in pharmacokinetics because of CRRT often required higher than labeled doses, suggesting renally adjusted or reno-protective doses may lead to subtherapeutic dosing regimens. A thorough understanding of the interplay between patient, drug, and CRRT-circuit factors are required to ensure adequate delivery of dosing regimens to this vulnerable population.

Population Pharmacokinetic Model-Based Evaluation of Intact Oxaliplatin in Rats with Acute Kidney Injury

Simple Summary

Acute kidney injury (AKI) complicates the dose setting of oxaliplatin (L-OHP), making it difficult to continue treatment cycles and retain antitumor efficacies with minimum L-OHP-related toxicities. Our study aimed to assess the impact of AKI on the pharmacokinetics of intact L-OHP and simulate the relationship between the degree of renal function and intact L-OHP exposures using a population pharmacokinetic model. Mild and severe renal dysfunction model rats were used to determine plasma and urine intact L-OHP concentration–time profiles after L-OHP administration. No significant differences in intact L-OHP levels between rats with normal renal function and those with renal dysfunction were observed, whereas renal excretion of intact L-OHP was correlated with renal function. Results of population PK model simulation suggested that dose reduction is dispensable for patients with mild to moderate AKI. The population PK modeling and simulation approach can contribute to developing an appropriate dose regimen of L-OHP for AKI patients.

Abstract

Acute kidney injury (AKI) complicates the dosing strategies of oxaliplatin (L-OHP) and the requirement for L-OHP dose reduction in patients with renal failure remains controversial. The objective of this study is to assess the impact of AKI on the pharmacokinetics (PK) of intact L-OHP and simulate the relationship between the degree of renal function and intact L-OHP exposures using a population PK model. Intact L-OHP concentrations in plasma and urine after L-OHP administration were measured in mild and severe AKI models established in rats through renal ischemia-reperfusion. Population PK modeling and simulation were performed. There were no differences among rats in the area under the plasma concentration–time curve of intact L-OHP after intravenous L-OHP administrations. Nevertheless, the amount of L-OHP excretion after administration of 8 mg/kg L-OHP in mild and severe renal dysfunction rats was 63.5% and 37.7%, respectively, and strong correlations were observed between biochemical renal function markers and clearance of intact L-OHP. The population PK model simulated well the observed levels of intact L-OHP in AKI model rats. The population PK model-based simulation suggests that dose reduction is unnecessary for patients with mild to moderate AKI.

Recent progress of microfluidic technology for pharmaceutical analysis

In recent years, the progress of microfluidic technology has provided new tools for pharmaceutical analysis and the proposal of pharm-lab-on-a-chip is appealing for its great potential to integrate pharmaceutical test and pharmacological test in a single chip system. Here, we summarize and highlight recent advances of chip-based principles, techniques and devices for pharmaceutical test and pharmacological/toxicological test focusing on the separation and analysis of drug molecules on a chip and the construction of pharmacological models on a chip as well as their demonstrative applications in quality control, drug screening and precision medicine. The trend and challenge of microfluidic technology for pharmaceutical analysis are also discussed and prospected. We hope this review would update the insight and development of pharm-lab-on-a-chip.

A Clinician's Guide to Dosing Analgesics, Anticonvulsants, and Psychotropic Medications in Continuous Renal Replacement Therapy

Acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT) is a common complication in critical illness and has a significant impact on pharmacokinetic factors determining drug exposure, including absorption, distribution, transport, metabolism, and clearance. In this review, we provide a practical guide to drug dosing considerations in critically ill patients undergoing CRRT, focusing on the most commonly used analgesic, anticonvulsant, and psychotropic medications in the clinical care of critically ill patients. A literature search was conducted to identify articles in which drug dosing was evaluated in adult patients receiving CRRT between the years 1980 and 2020. We included articles with pharmacokinetic/pharmacodynamic analyses and those that described medication clearance via CRRT. A summary of the data focused on practical pharmacokinetic and pharmacodynamic principles is presented, with recommendations for drug dosing of analgesics, anticonvulsants, and psychotropic medications. Pharmacokinetic and pharmacodynamic studies to guide drug dosing of analgesics, anticonvulsants, and psychotropic medications in critically ill patients receiving CRRT are sparse. Considering the widespread use of these medications, narrow therapeutic index of these drug classes, and risks of over- and underdosing, additional studies in patients receiving CRRT are needed to inform drug dosing.

Drug dosing considerations in continuous renal replacement therapy

Acute kidney injury (AKI) is a common complication in critically ill patients, which is associated with increased in-hospital mortality. Delivering effective antibiotics to treat patients with sepsis receiving continuous renal replacement therapy (RRT) is complicated by variability in pharmacokinetics, dialysis delivery, lack of primary literature, and therapeutic drug monitoring. Pharmacokinetic alterations include changes in absorption, distribution, protein binding (PB), metabolism, and renal elimination. Drug absorption may be significantly changed due to alterations in gastric pH, perfusion, gastrointestinal motility, and intestinal atrophy. Volume of distribution for hydrophilic drugs may be increased due to volume overload. Estimation of renal clearance is challenged by the effective delivery of RRT. Drug characteristics such as PB, volume of distribution, and molecular weight impact removal of the drug by RRT. The totality of these alterations leads to reduced exposure. Despite our best knowledge, therapeutic drug monitoring of patients receiving continuous RRT demonstrates wide variability in antimicrobial concentrations, highlighting the need for expanded monitoring of all drugs. This review article will focus on changes in drug pharmacokinetics in AKI and dosing considerations to attain antibiotic pharmacodynamic targets in critically ill patients receiving continuous RRT.

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.

Optimal levofloxacin dosing regimens in critically ill patients with acute kidney injury receiving continuous renal replacement therapy

PURPOSES

To determine appropriate dosing of levofloxacin in critically ill patients receiving continuous renal replacement therapy (CRRT).

METHODS

All necessary pharmacokinetic and pharmacodynamic parameters from critically ill patients were obtained to develop mathematical models with first order elimination. Levofloxacin concentration-time profiles were calculated to determine the efficacy based on the probability of target attainment (PTA) of AUC_24h/MIC ≥50 for Gram-positive and AUC_24h/MIC ≥125 for Gram-negative infections. A group of 5000 virtual patients was simulated and tested using Monte Carlo simulations for each dose in the models. The optimal dosing regimens were defined as the dose achieved target PTA at least 90% of the virtual patients.

RESULTS

No conventional, FDA approved regimens achieved at least 90% of PTA for Gram-negative infection with Pseudomonas aeruginosa at MIC of 2 mg/L. The successful dose (1750 mg on day 1, then 1500 mg q 24 h) was far exceeded the maximum FDA-approved doses. For Gram-positive infections, a levofloxacin 750 mg q 24 h was sufficient to attain PTA target of ~90% at the MIC of 2 mg/L for Streptococcus pneumoniae.

CONCLUSIONS

Levofloxacin cannot be recommended as an empiric monotherapy for serious Gram-negative infections in patients receiving CRRT due to suboptimal efficacy.

Renal Dosing of Antibiotics: Are We Jumping the Gun?

Antibiotic renal dose adjustments are determined in patients with stable chronic kidney disease and may not translate to patients in late-phase trials and practice. Ceftolozane/tazobactam, ceftazidime/avibactam, and telavancin all carry precautionary statements for reduced clinical response in patients with baseline creatinine clearance of 30-50 mL/min, potentially due to unnecessary dose reduction in the setting of acute kidney injury (AKI). In this review, we discuss the regulatory landscape for antibiotics eliminated by the kidney and highlight the importance of the first 48 hours of therapy. Using a clinical database, we identified AKI on admission in a substantial proportion of patients with pneumonia (27.1%), intraabdominal (19.5%), urinary tract (20.0%), or skin and skin structure infections (9.7%) that resolved by 48 hours in 57.2% of cases. We suggest that deferred renal dose reduction of wide therapeutic index antibiotics could improve outcomes in patients with infectious diseases.

Principles of Drug Dosing in Sustained Low Efficiency Dialysis (SLED) and Review of Antimicrobial Dosing Literature

The use of sustained low-efficiency dialysis (SLED) as a renal replacement modality has increased in critically ill patients with both acute kidney injury (AKI) and hemodynamic instability. Unfortunately, there is a paucity of data regarding the appropriate dosing of medications for patients undergoing SLED. Dose adjustment in SLED often requires interpretation of pharmacodynamics and pharmacokinetic factors and extrapolation based on dosing recommendations from other modes of renal replacement therapy (RRT). This review summarizes published trials of antimicrobial dose adjustment in SLED and discusses pharmacokinetic considerations specific to medication dosing in SLED. Preliminary recommendation is provided on selection of appropriate dosing for medications where published literature is unavailable.

[Pharmacokinetics and pharmacodynamics in extracorporeal renal replacement therapy]

Intermittent hemodialysis, continuous hemofiltration and prolonged daily dialysis are used for renal replacement therapy in the intensive care units. Independent of the replacement modality, antibiotic therapy must start with a high loading dose. Dose adjustment to the kidneys must follow 48 h later to prevent toxic accumulation. Dose recommendations on product labels are often underdosed. On continuous hemofiltration, meanwhile many intensivists administer a normal standard dose because the high filtration rate corresponds to a half-normal glomerular filtration rate. After intermittent hemodialysis, a dose similar to the loading dose will be needed. On day off dialysis, the maintenance dose must be adjusted to the failing kidney function. Immediately after prolonged daily dialysis, a loading dose should be given; with twice daily dosing the maintenance dose needs to be adjusted to kidney function. Therapeutic drug monitoring is recommended for gentamicin, vancomycin, piperacillin, meropenem and voriconazole. Due to pharmacodynamic reasons, the target concentration corresponds to the concentration producing the half-maximum effect. Accordingly, the target concentration is the normal peak for concentration-dependent action with bolus dosing. The target is the average steady-state concentration for antibiotics with time-dependent action and continuous infusion.

Drug Dosing Considerations in Critically Ill Patients Receiving Continuous Renal Replacement Therapy

Acute kidney injury is very common in critically ill patients requiring renal replacement therapy. Despite the advancement in medicine, the mortality rate from septic shock can be as high as 60%. This manuscript describes drug-dosing considerations and challenges for clinicians. For instance, drugs’ pharmacokinetic changes (e.g., decreased protein binding and increased volume of distribution) and drug property changes in critical illness affecting solute or drug clearance during renal replacement therapy. Moreover, different types of renal replacement therapy (intermittent hemodialysis, prolonged intermittent renal replacement therapy or sustained low-efficiency dialysis, and continuous renal replacement therapy) are discussed to describe how to optimize the drug administration strategies. With updated literature, pharmacodynamic targets and empirical dosing recommendations for commonly used antibiotics in critically ill patients receiving continuous renal replacement therapy are outlined. It is vital to utilize local epidemiology and resistance patterns to select appropriate antibiotics to optimize clinical outcomes. Therapeutic drug monitoring should be used, when possible. This review should be used as a guide to develop a patient-specific antibiotic therapy plan.

Effect of renal ischaemia/reperfusion-induced acute kidney injury on pharmacokinetics of midazolam in rats

OBJECTIVES

This study aimed to investigate the effects of renal ischaemia/reperfusion (I/R)-induced acute kidney injury (AKI) on the distribution of midazolam (MDZ), a probe drug for cytochrome P450 3A (CYP3A) activity.

METHODS

We established an AKI model inducing ischaemia of both renal pedicles for 60 min followed by 24-h reperfusion. MDZ was administered intravenously (i.v.) to the rats via the jugular vein, and then, blood samples were collected to determine the plasma concentration of MDZ.

KEY FINDINGS

While the plasma concentration of MDZ after i.v. administration was decreased in the I/R rats, the tissue concentration was not altered. In addition, the tissue-to-plasma (T/P) ratio of MDZ was increased in the I/R rats. The unbound fraction of MDZ and the level of indoxyl sulphate (IS) in plasma were elevated in the I/R rats. Furthermore, the unbound fraction of MDZ was significantly increased by the addition of IS.

CONCLUSIONS

These results indicated that the displacement of albumin-bound MDZ by IS changed the unbound fraction of MDZ and elevated the T/P ratio of MDZ in I/R rats.

Antibiotic Dosing for Critically Ill Adult Patients Receiving Intermittent Hemodialysis, Prolonged Intermittent Renal Replacement Therapy, and Continuous Renal Replacement Therapy: An Update

Objective: To summarize current antibiotic dosing recommendations in critically ill patients receiving intermittent hemodialysis (IHD), prolonged intermittent renal replacement therapy (PIRRT), and continuous renal replacement therapy (CRRT), including considerations for individualizing therapy. Data Sources: A literature search of PubMed from January 2008 to May 2019 was performed to identify English-language literature in which dosing recommendations were proposed for antibiotics commonly used in critically ill patients receiving IHD, PIRRT, or CRRT. Study Selection and Data Extraction: All pertinent reviews, selected studies, and references were evaluated to ensure appropriateness for inclusion. Data Synthesis: Updated empirical dosing considerations are proposed for antibiotics in critically ill patients receiving IHD, PIRRT, and CRRT with recommendations for individualizing therapy. Relevance to Patient Care and Clinical Practice: This review defines principles for assessing renal function, identifies RRT system properties affecting drug clearance and drug properties affecting clearance during RRT, outlines pharmacokinetic and pharmacodynamic dosing considerations, reviews pertinent updates in the literature, develops updated empirical dosing recommendations, and highlights important factors for individualizing therapy in critically ill patients. Conclusions: Appropriate antimicrobial selection and dosing are vital to improve clinical outcomes. Dosing recommendations should be applied cautiously with efforts to consider local epidemiology and resistance patterns, antibiotic dosing and infusion strategies, renal replacement modalities, patient-specific considerations, severity of illness, residual renal function, comorbidities, and patient response to therapy. Recommendations provided herein are intended to serve as a guide in developing and revising therapy plans individualized to meet a patient's needs.

Effects of infection of MRSA on the expression and activity of renal cytochrome P450s in mice

Methicillin-resistant Staphylococcus aureus (MRSA) leads to serious infections, but it is not known whether it changes the expression of kidney drug metabolizing enzymes during infection. The mice were infected with different doses of MRSA and the oxidative stress and inflammation levels in the kidney were examined. The mRNA expression and activity of cytochrome P450 enzyme was analysed. Mice infected with high levels of MRSA showed a decrease in renal antioxidant capability and an elevated level of oxidative metabolites, which was accompanied by the release of inflammatory cytokines. The levels of interleukin 1β, tumour necrosis factor alpha, and macrophage inflammatory protein-1α were significantly increased along with the levels of nitric oxide and malondialdehyde. On day 7, mRNA expression of Cyp1a2, 2d22, and 3a11 were decreased by the high level of MRSA, but the low level of MRSA increased their expressions. Cyp2e1 mRNA expression was increased by MRSA in the kidney of mice. High dose of MRSA infection increased the oxidative stress and inflammatory response in mouse kidney, leading to the decrease in the expression of renal drug-metabolizing enzymes and no recovery within 7 days.

Optimal vancomycin dosing regimens for critically ill patients with acute kidney injury during continuous renal replacement therapy: A Monte Carlo simulation study

PURPOSE

This study aims to determine the optimal vancomycin dosing in critically ill patients with acute kidney injury receiving continuous renal replacement therapy (CRRT) using Monte Carlo simulation.

METHODS

A one compartment pharmacokinetic model was conducted to define vancomycin deposition for the initial 48hours of therapy. Pharmacokinetic parameters were gathered from previously published studies. The AUC₂₄/MIC ratio of at least 400 and an average of AUC_0-24 at > 700mgh/L were utilized to evaluate efficacy and nephrotoxicity, respectively. The doses achieved at least 90% of the probability of target attainment (PTA) with the lowest risk of nephrotoxicity defined as the optimal dose.

RESULTS

The regimens of 1.75grams every 24hours and 1.5grams loading followed by 500mg every 8hours were recommended for empirical therapy of an MRSA infection with expected MIC ≤1mg/L, and definite therapy with actual MIC of 1mg/L. The probabilities of nephrotoxic results from these regimens were 35%.

CONCLUSIONS

A higher dose of vancomycin than the current literature-based recommendation was needed in CRRT patients.

The prominent impairment of liver/intestinal cytochrome P450 and intestinal drug transporters in sepsis-induced acute kidney injury over acute and chronic renal ischemia, a mouse model comparison

Drug dosing adjustment in sepsis-induced acute kidney injury (sepsis-AKI) is currently adjusted based on renal function. Sepsis is a multiorgan injury, and thus, drug metabolism in sepsis-AKI might be interfered by non-renal factors such as changes in functions of drug-metabolizing enzymes in the liver and functions of intestinal drug transporters. We compared the defect on mouse CYP3A11 (human CYP3A4 representative) in liver and intestine along with several intestinal drug transporters (MDR1a, MRP2, and OATP3) in three mouse models; chronic ischemic reperfusion injury (Chr I/R; 4-week), acute ischemic reperfusion injury (Acute I/R; 24-h), and cecal ligation and puncture (CLP; 24-h) as representative of sepsis-AKI. Decreased expression of CYP3A11 and drug transporters was demonstrated in all models. Among these models, sepsis-AKI had the least severe renal injury (increased BUN and Scr) with the most severe liver injury (increased ALT and changes in liver histopathology), the most severe intestinal leakage (increased serum (1→3)-β-D-glucan) and the highest increase in serum IL-6. A reduced expression and activity of liver and intestinal CYP3A11 along with intestinal efflux-drug transporter expressions (MDR1a and MRP2), but not drug uptake transporter (OATP3), was predominant in sepsis-AKI compared with acute I/R. Additionally, a reduction of CYP3A4 expression with IL-6 was demonstrated on HepG2 cells implying a direct injury of IL-6 on human liver cells. Differences in drug metabolism were reported between sepsis-AKI and ischemic-AKI confirming that drug dosing adjustment in sepsis-AKI depends not just only on renal function but also on several non-renal factors. Further studies are warranted.

Acute Kidney Injury Pharmacokinetic Changes and Its Impact on Drug Prescription

Acute kidney injury (AKI) is a common problem in hospitalized patients that is associated with significant morbid-mortality. The impact of kidney disease on the excretion of drugs eliminated by glomerular filtration and tubular secretion is well established, as well as the requirement for drug dosage adjustment in impaired kidney function patients. However, since impaired kidney function is associated with decreased activity of several hepatic and gastrointestinal drug-metabolizing enzymes and transporters, drugs doses adjustment only based on kidney alteration could be insufficient in AKI. In addition, there are significant pharmacokinetics changes in protein binding, serum amino acid levels, liver, kidney, and intestinal metabolism in AKI, thus the determination of plasma drug concentrations is a very useful tool for monitoring and dose adjustment in AKI patients. In conclusion, there are many pharmacokinetics changes that should be taken into account in order to perform appropriate drug prescriptions in AKI patients.

PPAR gamma agonist, pioglitazone, rescues liver damage induced by renal ischemia/reperfusion injury

Remote organ damage is the major cause of death in patients with acute kidney injury (AKI) due to renal ischemia reperfusion (IR). Liver is one of the vital organs which are profoundly affected by AKI. The present study aims to investigate the role of peroxisome proliferator activator receptor gamma (PPARγ) in liver damage induced by IR injury in rats. Renal IR was induced by right nephrectomy, occlusion of left renal pedicle for 45 min to induce ischemia, and then reperfusion for 6 or 24 h. The PPARγ agonist, pioglitazone, was given orally for 7 days before renal IR procedure. Animals receiving pioglitazone showed improvement in renal and hepatic functions when compared to IR groups. Renal IR increased renal, hepatic and serum levels of tumor necrosis factor-α (TNF-α) and induced apoptotic cell death in liver. These effects were diminished with pioglitazone. In addition, pioglitazone reduced renal IR-induced oxidative stress in liver. Pioglitazone reduced malondialdehyde (MDA) content and NADPH oxidase mRNA expression and induced further increase in nuclear factor erythroid 2-related factor 2 (Nrf2) expression when compared to IR groups. Furthermore, pioglitazone increased the expression of PPARγ target genes such as renal and hepatic PPARγ1 (Pparg1), hepatic hemoxygenase-1 (Hmox1), and hepatic thioredoxin (TRx). Histological profiles for kidney and liver were also ameliorated with pioglitazone. Hence, PPARγ is a potential target to protect liver in patients with renal IR injury.

Use of Estimating Equations for Dosing Antimicrobials in Patients with Acute Kidney Injury Not Receiving Renal Replacement Therapy

Acute kidney injury (AKI) can potentially lead to the accumulation of antimicrobial drugs with significant renal clearance. Drug dosing adjustments are commonly made using the Cockcroft-Gault estimate of creatinine clearance (CLcr). The Modified Jelliffe equation is significantly better at estimating kidney function than the Cockcroft-Gault equation in the setting of AKI. The objective of this study is to assess the degree of antimicrobial dosing discordance using different glomerular filtration rate (GFR) estimating equations. This is a retrospective evaluation of antimicrobial dosing using different estimating equations for kidney function in AKI and comparison to Cockcroft-Gault estimation as a reference. Considering the Cockcroft-Gault estimate as the criterion standard, antimicrobials were appropriately adjusted at most 80.7% of the time. On average, kidney function changed by 30 mL/min over the course of an AKI episode. The median clearance at the peak serum creatinine was 27.4 (9.3–66.3) mL/min for Cockcroft Gault, 19.8 (9.8–47.0) mL/min/1.73 m² for MDRD and 20.5 (4.9–49.6) mL/min for the Modified Jelliffe equations. The discordance rate for antimicrobial dosing ranged from a minimum of 8.6% to a maximum of 16.4%. In the event of discordance, the dose administered was supra-therapeutic 100% of the time using the Modified Jelliffe equation. Use of estimating equations other than the Cockcroft Gault equation may significantly alter dosing of antimicrobials in AKI.

Clinical Pharmacokinetics in Kidney Disease: Application to Rational Design of Dosing Regimens

A change in pharmacokinetics can alter drug exposure and predispose the patient to either over- or underdosing, potentially resulting in adverse drug reactions or therapeutic failure. Kidney disease is characterized by multiple physiologic effects, which induce clinically significant changes in pharmacokinetics. These vary between individuals and may be quantitated in certain instances. An understanding of pharmacokinetic concepts is, therefore, important for a rational approach to the design of drug dosing regimens for the delivery of personalized medical care. Whether kidney disease is acute or chronic, drug clearance decreases and the volume of distribution may remain unchanged or increase. AKI is defined by dynamic changes in kidney function, which complicates attempts to accurately quantify drug clearance. In contrast, changes in drug clearance progress more slowly with CKD. In general, kidney replacement therapies increase drug clearance, but the extent to which this occurs depends on the modality used and its duration, the drug's properties, and the timing of drug administration. However, the changes in drug handling associated with kidney disease are not isolated to reduced kidney clearance and an appreciation of the scale of potential derangements is important. In most instances, the first dose administered in patients with kidney disease is the same as in patients with normal kidney function. However, in some cases, a higher (loading) initial dose is given to rapidly achieve therapeutic concentrations, followed by a lower maintenance dose, as is well described when prescribing anti-infectives to patients with sepsis and AKI. This review provides an overview of how pharmacokinetic principles can be applied to patients with kidney disease to personalize dosage regimens. Patients with kidney disease are a vulnerable population and the increasing prevalence of kidney disease means that these considerations are important for all prescribers.

Distant Organ Dysfunction in Acute Kidney Injury: A Review

Acute kidney injury (AKI) is common in critically ill patients and is associated with increased morbidity and mortality. Dysfunction of other organs is an important cause of poor outcomes from AKI. Ample clinical and epidemiologic data show that AKI is associated with distant organ dysfunction in lung, heart, brain, and liver. Recent advancements in basic and clinical research have demonstrated physiologic and molecular mechanisms of distant organ interactions in AKI, including leukocyte activation and infiltration, generation of soluble factors such as inflammatory cytokines/chemokines, and endothelial injury. Oxidative stress and production of reactive oxygen species, as well as dysregulation of cell death in distant organs, are also important mechanism of AKI-induced distant organ dysfunction. This review updates recent clinical and experimental findings on organ crosstalk in AKI and highlights potential molecular mechanisms and therapeutic targets to improve clinical outcomes during AKI.

[Dose adjustment of anti-infective drugs in patients with renal failure and renal replacement therapy in intensive care medicine : Recommendations from the renal section of the DGIIN, ÖGIAIN and DIVI]

BACKGROUND

Many anti-infective drugs require dose adjustments in critically ill patients with acute kidney injury (AKI) and renal replacement therapy, in order to achieve adequate therapeutic drug concentrations.

OBJECTIVES

The fundamental pharmacokinetic and pharmacodynamic principles of drug dose adjustment are presented. Recommendations on anti-infective drug dosage in intensive care are provided.

MATERIALS AND METHODS

We established dose recommendations of selected anti-infective drugs based on information in the summary of product characteristics, published studies and recommendations, pharmacokinetic and pharmacodynamic considerations, and the experience and expert opinion of the authors.

RESULTS

Out of a total of 37 anti-infective drugs (31 antibiotics, 2 antivirals, 4 antifungals) 8 can be administered independent of renal function. For 29 anti-infective drugs, a specific recommendation on drug dosage could be made in case of intermittent hemodialysis and for 24 anti-infective drugs in case of continuous hemo(dia)filtration.

CONCLUSIONS

Recommendations on dosing of important anti-infective drugs in critically ill patients with AKI and renal replacement therapy are provided.

Telavancin and Hydroxy Propyl-β-Cyclodextrin Clearance during Continuous Renal Replacement Therapy: An in vitro Study

Background/Aims

Telavancin is a lipoglycopeptide antimicrobial agent which has been approved in Europe and has been recently FDA approved in the United States. Telavancin's parenteral solution contains hydroxy propyl-β-cyclodextrin (HP-β-CD) to enhance its solubility. The disposition of telavancin and HP-β-CD during continuous renal replacement therapies (CRRT) has not been previously reported.

Methods

The transmembrane clearances (CLtm) of telavancin and HP-β-CD during continuous hemofiltration and hemodialysis were assessed using an in vitro bovine blood model with AN69 and polysulfone hemodiafilters at varying ultrafiltrate and dialysate flow rates (1, 2, 3, & 6 l/hr).

Results

The mean telavancin sieving coefficient ranged from 0.25 to 0.31 during continuous hemofiltration. At all ultrafiltration rates, no differences were observed in telavancin CLtm between the two hemodiafilter types. For continuous hemodialysis, mean telavancin saturation coefficients ranged from 0.10 to 0.43 and CLtm tended to be higher for the polysulfone hemodiafilter than the AN69 hemodiafilter, especially at higher flow rates. Mean HP-β-CD sieving coefficients ranged from 0.63 to 1.03 and saturation coefficients from 0.63 to 1.38, resulting in a CLtm that was similar to ultrafiltrate and dialysate flow rates.

Conclusion

Telavancin CLtm is dependent on hemodiafilter type, dialysate and ultrafiltration rates. CRRT with high ultrafiltrate or dialysate rates may result in sufficient telavancin clearance to alter telavancin dosing. HP-β-CD clearance by continuous hemodialysis or continuous hemofiltration is substantial and may be sufficient to prevent HP-β-CD accumulation in subjects receiving CRRT. Pharmacokinetic studies conducted in patients receiving CRRT and telavancin are needed to confirm these in vitro findings.

The effects of major burn related pathophysiological changes on the pharmacokinetics and pharmacodynamics of drug use: An appraisal utilizing antibiotics

Patients suffering major burn injury represent a unique population of critically ill patients. Widespread skin and tissue damage causes release of systemic inflammatory mediators that promote endothelial leak, extravascular fluid shifts, and cardiovascular derangement. This phase is characterized by relative intra-vascular hypovolaemia and poor peripheral perfusion. Large volume intravenous fluid resuscitation is generally required. The patients' clinical course is then typically complicated by ongoing inflammation, protein catabolism, and marked haemodynamic perturbation. At all times, drug distribution, metabolism, and elimination are grossly distorted. For hydrophilic agents, changes in volume of distribution and clearance are marked, resulting in potentially sub-optimal drug exposure. In the case of antibiotics, this may then promote treatment failure, or the development of bacterial drug resistance. As such, empirical dose selection and pharmaceutical development must consider these features, with the application of strategies that attempt to counter the unique pharmacokinetic changes encountered in this setting.

Medication Complications in Extracorporeal Membrane Oxygenation

The need for extracorporeal membrane oxygenation (ECMO) therapy is a marker of disease severity for which multiple medications are required. The therapy causes physiologic changes that impact drug pharmacokinetics. These changes can lead to exposure-driven decreases in efficacy or increased incidence of side effects. The pharmacokinetic changes are drug specific and largely undefined for most drugs. We review available drug dosing data and provide guidance for use in the ECMO patient population.

Acetaminophen clearance during ex vivo continuous renal replacement therapies

Intravenous acetaminophen is an adjuvant to opioid use in critically ill and surgical patients requiring continuous renal replacement therapy (CRRT). The objective of this study was to determine the ex vivo transmembrane clearance of intravenous acetaminophen during continuous hemofiltration and hemodialysis. Transmembrane clearance was assessed using a validated ex vivo bovine blood model for CRRT using an F8 or HF1400 hemodiafilter. Ultrafiltrate and dialysate flow rates were 1, 2, and 3 L/h. Urea and acetaminophen clearances were calculated and compared. Acetaminophen was readily cleared by continuous hemofiltration with both hemodiafilters. Acetaminophen clearance rates were 92-98% of ultrafiltrate production rates. Similarly, dialytic acetaminophen clearances approximated dialysate flow rates for both hemodiafilters. Acetaminophen is readily cleared by CRRT. Patients receiving CRRT and acetaminophen may require increased doses for adequate pain control.

Dual Organ Duel: The Hepatorenal Axis

Recent developments in our understanding of the pathogenesis of kidney disease in the setting of liver failure have highlighted that kidney injury, rather than occurring in isolation, is a marker of systemic disease and poor prognosis. The differential diagnosis of kidney disease associated with liver failure is broader than formerly described and new biopsy data, along with better acute kidney injury classification tools, have increased appreciation for distinct pathophysiological mechanisms. Evidence suggests that acute kidney injury contributes to worsening hepatic failure by directly injuring hepatic cells and by imposing restrictions on therapeutic strategies for portal hypertension. Furthermore, kidney injury limits the use of various therapeutic agents and increases their toxicity due to altered pharmacodynamics. A greater appreciation of CKD in this population is also overdue because management decisions are affected and increased vigilance may avoid further kidney injury. A multidisciplinary approach to kidney injury in the setting of liver failure will enable targeted therapeutic strategies that are safe and effective and serve to guide further research, while limiting clinical potential for harm. Finally, new hepatitis C antiviral therapies promise to change the landscape of liver failure, and a discussion of kidney risk factors and antiviral therapy of patients with kidney disease and hepatitis C is worthwhile.

The 6R's of drug induced nephrotoxicity

Drug induced kidney injury is a frequent adverse event which contributes to morbidity and increased healthcare utilization. Our current knowledge of drug induced kidney disease is limited due to varying definitions of kidney injury, incomplete assessment of concurrent risk factors and lack of long term outcome reporting. Electronic surveillance presents a powerful tool to identify susceptible populations, improve recognition of events and provide decision support on preventative strategies or early intervention in the case of injury. Research in the area of biomarkers for detecting kidney injury and genetic predisposition for this adverse event will enhance detection of injury, identify those susceptible to injury and likely mitigate risk. In this review we will present a 6R framework to identify and mange drug induced kidney injury – risk, recognition, response, renal support, rehabilitation and research.

[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.

Impact of acute kidney injury on distant organ function: recent findings and potential therapeutic targets

Acute kidney injury (AKI) is a common complication in critically ill patients and subsequently worsens outcomes. Although many drugs to prevent and treat AKI have shown benefits in preclinical models, no specific agent has been shown to benefit AKI in humans. Moreover, despite remarkable advances in dialysis techniques that enable management of AKI in hemodynamically unstable patients with shock, dialysis-requiring severe AKI is still associated with an unacceptably high mortality rate. Thus, focusing only on kidney damage and loss of renal function has not been sufficient to improve outcomes of patients with AKI. Recent data from basic and clinical research have begun to elucidate complex organ interactions in AKI between kidney and distant organs, including heart, lung, spleen, brain, liver, and gut. This review serves to update the topic of organ cross talk in AKI and focuses on potential therapeutic targets to improve patient outcomes during AKI-associated multiple organ failure.