Pharmacokinetics and pharmacodynamics of antibiotics in critically ill acute kidney injury patients

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.

Effect of Yttrium doping on antibacterial and antioxidant property of LaTiO3

The advancement of multidrug-resistant bacterial strains and their adverse effects is one of the most significant global health issues. The perovskite nanomaterial with combined antioxidant and antibacterial activities in one molecule has the potential for improved therapeutic solutions. In this work, Yttrium-doped Lanthanum Titanate (LaTi1 -xYxO3, where x = 0, 0.05, and 0.1) was synthesized using auto combustion technique. Excellent crystalline structure with a tetragonal system is revealed by X-ray diffraction analysis (XRD). UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS), Fourier transform infrared (FTIR), and photoluminescence (PL) were used to study its optical characteristics. The field emission scanning electron microscope (FE-SEM) shows rod-like pellet-shaped Yttrium-doped nanostructures, and the elements present were confirmed with the Energy Dispersive X-Ray Analysis (EDAX). Various concentrations of the synthesized materials were tested for antibacterial activity against Gram-positive (Staphylococcus aureus 902) and Gram-negative (E. coli 443) strains using the agar-well diffusion method with gentamicin antibiotic as a positive control. High antibacterial activity of 87.1% and 83.3% was shown by 10% Yttrium-doped LaTiO3 (LY(0.1)TO) at 500 mg/mL against both positive and negative stains, respectively. Moreover, the antioxidant properties of synthesized materials were assessed with IC50 values of 352.33 µg/mL, 458.055 µg/mL, and 440.163 µg/mL for samples LaTi1 - xYxO3, where x = 0, 0.05, and 0.1 respectively. The antibacterial and antioxidant capabilities of the proposed samples illustrate their applicability in various biomedical applications.

Meropenem extraction by ex vivo extracorporeal life support circuits

BACKGROUND

Meropenem is a broad-spectrum carbapenem-type antibiotic commonly used to treat critically ill patients infected with extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. As many of these patients require extracorporeal membrane oxygenation (ECMO) and/or continuous renal replacement therapy (CRRT), it is important to understand how these extracorporeal life support circuits impact meropenem pharmacokinetics. Based on the physicochemical properties of meropenem, it is expected that ECMO circuits will minimally extract meropenem, while CRRT circuits will rapidly clear meropenem. The present study seeks to determine the extraction of meropenem from ex vivo ECMO and CRRT circuits and elucidate the contribution of different ECMO circuit components to extraction.

METHODS

Standard doses of meropenem were administered to three different configurations (n = 3 per configuration) of blood-primed ex vivo ECMO circuits and serial sampling was conducted over 24 h. Similarly, standard doses of meropenem were administered to CRRT circuits (n = 4) and serial sampling was conducted over 4 h. Meropenem was administered to separate tubes primed with circuit blood to serve as controls to account for drug degradation. Meropenem concentrations were quantified, and percent recovery was calculated for each sample.

RESULTS

Meropenem was cleared at a similar rate in ECMO circuits of different configurations (n = 3) and controls (n = 6), with mean (standard deviation) recovery at 24 h of 15.6% (12.9) in Complete circuits, 37.9% (8.3) in Oxygenator circuits, 47.1% (8.2) in Pump circuits, and 20.6% (20.6) in controls. In CRRT circuits (n = 4) meropenem was cleared rapidly compared with controls (n = 6) with a mean recovery at 2 h of 2.36% (1.44) in circuits and 93.0% (7.1) in controls.

CONCLUSION

Meropenem is rapidly cleared by hemodiafiltration during CRRT. There is minimal adsorption of meropenem to ECMO circuit components; however, meropenem undergoes significant degradation and/or plasma metabolism at physiological conditions. These ex vivo findings will advise pharmacists and physicians on the appropriate dosing of meropenem.

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.

Extracorporeal blood purification therapies for sepsis-associated acute kidney injury in critically ill patients: expert opinion from the SIAARTI-SIN joint commission

Sepsis-Associated Acute Kidney Injury is a life-threatening condition leading to high morbidity and mortality in critically ill patients admitted to the intensive care unit. Over the past decades, several extracorporeal blood purification therapies have been developed for both sepsis and sepsis-associated acute kidney injury management. Despite the widespread use of extracorporeal blood purification therapies in clinical practice, it is still unclear when to start this kind of treatment and how to define its efficacy. Indeed, several questions on sepsis-associated acute kidney injury and extracorporeal blood purification therapy still remain unresolved, including the indications and timing of renal replacement therapy in patients with septic vs. non-septic acute kidney injury, the optimal dialysis dose for renal replacement therapy modalities in sepsis-associated acute kidney injury patients, and the rationale for using extracorporeal blood purification therapies in septic patients without acute kidney injury. Moreover, the development of novel extracorporeal blood purification therapies, including those based on the use of adsorption devices, raised the attention of the scientific community both on the clearance of specific mediators released by microorganisms and by injured cells and potentially involved in the pathogenic mechanisms of organ dysfunction including sepsis-associated acute kidney injury, and on antibiotic removal. Based on these considerations, the joint commission of the Italian Society of Anesthesiology and Critical Care (SIAARTI) and the Italian Society of Nephrology (SIN) herein addressed some of these issues, proposed some recommendations for clinical practice and developed a common framework for future clinical research in this field.

Beta-lactam exposure and safety in intermittent or continuous infusion in critically ill children: an observational monocenter study

The aim of this study was to assess the pharmacokinetic (PK) exposure and clinical toxicity for three beta-lactams: cefotaxime, piperacillin/tazobactam, and meropenem, depending on two lengths of infusion: continuous and intermittent, in critically ill children. This single center observational prospective study was conducted in a pediatric intensive care unit. All hospitalized children who had one measured plasma concentration of the investigated antibiotics were included. Plasma antibiotic concentrations were interpreted by a pharmacologist, using a Bayesian approach based on previously published population pharmacokinetic models in critically ill children. Exposure was considered optimal, low, or high according to the PK target 100% fT_{> 4 × MIC} and a trough concentration below the toxic concentration (50 mg.L^-1 for cefotaxime, 150 mg.L^-1 for piperacillin, and 44 mg.L^-1 for meropenem). Between May 2019 and January 2020, 80 patients were included and received 106 antibiotic courses: 74 (70%) were administered in intermittent infusion (II) and 32 (30%) in continuous infusion (CI). Compared to II, CI provided more optimal PK exposure (n = 22/32, 69% for CI versus n = 35/74, 47% for II, OR 1.2, 95%CI 1.01-1.5, p = 0.04), less underexposure (n = 4/32, 13% for CI versus n = 36/74, 49% for II, OR 0.7, 95%CI 0.6-0.84, p < 0.001), and more overexposure (n = 6/32, 19% for CI versus n = 3/74, 4% for II, OR 1.2, 95%CI 1.03-1.3, p = 0.01). Five adverse events have been reported during the study period, although none has been attributed to beta-lactam treatment.

CONCLUSION

CI provided a higher probability to attain an optimal PK target compared to II, but also a higher risk for overexposure. Regular therapeutic drug monitoring is recommended in critically ill children receiving beta-lactams, regardless of the length of infusion.

WHAT IS KNOWN

• Since beta-lactams are time-dependent antibiotics, the probability to attain the pharmacokinetic target is higher with continuous infusion compared to that with intermittent infusion. • In daily practice, continuous or extended infusions are rarely used despite recent guidelines, and toxicity is hardly reported.

WHAT IS NEW

• Continuous infusion provided a higher probability to attain an optimal pharmacokinetic target compared to intermittent infusion, but also a higher risk of overexposure. • Regular therapeutic drug monitoring is recommended in critically ill children receiving beta-lactams, regardless of the length of infusion.

Measured versus estimated creatinine clearance in critically ill patients with acute kidney injury: an observational study

Background

Acute kidney injury (AKI) commonly occurs in critically ill patients. Estimation of renal function and antibiotics dose adjustment in patients with AKI is a challenging issue.

Methods

Urinary creatinine clearance was measured in a 6-hour urine collection from patients with acute kidney injuries. The correlations between different formulas including the modified Cockcroft-Gault, modification of diet in renal disease, chronic kidney disease-epidemiology collaboration, Jelliffe, kinetic-glomerular filtration rate (GFR), Brater, and Chiou formulas were considered. The pattern of the prescribed antimicrobial agents was also compared with the patterns in the available resources.

Results

Ninety-five patients with acute kidney injuries were included in the research. The mean age of the participants was 63.11±17.58 years old. The most patients (77.89%) were in stage 1 of AKI according to the Acute Kidney Injury Network criteria, followed by stage 2 (14.73%) and stage 3 (7.36), respectively. None of the formulations had a high or very high correlation with the measured creatinine clearance. In stage 1, Chiou (r=0.26), and in stage 2 and 3, kinetic-GFR (r=0.76 and r=0.37) had the highest correlation coefficient. Antibiotic over- and under-dosing were frequently observed in the study.

Conclusions

The results showed that none of the static methods can predict the measured creatinine clearance in the critically ill patients. The dynamic methods such as kinetic-GFR can be helpful for patients who do not receive diuretics and vasopressors. Further studies are needed to confirm our results.

The Serum Concentration of Vancomycin as a Diagnostic Predictor of Nephrotoxic Acute Kidney Injury in Critically Ill Patients

The impact of serum concentrations of vancomycin is a controversial topic. Results: 182 critically ill patients were evaluated using vancomycin and 63 patients were included in the study. AKI occurred in 44.4% of patients on the sixth day of vancomycin use. Vancomycin higher than 17.53 mg/L between the second and the fourth days of use was a predictor of AKI, preceding AKI diagnosis for at least two days, with an area under the curve of 0.806 (IC 95% 0.624–0.987, p = 0.011). Altogether, 46.03% of patients died, and in the Cox analysis, the associated factors were age, estimated GFR, CPR, and vancomycin between the second and the fourth days. Discussion: The current 2020 guidelines recommend using Bayesian-derived AUC monitoring rather than trough concentrations. However, due to the higher number of laboratory analyses and the need for an application to calculate the AUC, many centers still use therapeutic trough levels between 15 and 20 mg/L. Conclusion: The results of this study suggest that a narrower range of serum concentration of vancomycin was a predictor of AKI in critically ill septic patients, preceding the diagnosis of AKI by at least 48 h, and it can be a useful monitoring tool when AUC cannot be used.

Correlation of antimicrobial fraction unbound and sieving coefficient in critically ill patients on continuous renal replacement therapy: a systematic review

Background

Fraction unbound has been used as a surrogate for antimicrobial sieving coefficient (SC) to predict extracorporeal clearance in critically ill patients on continuous renal replacement therapy (CRRT), but this is based largely on expert opinion.

Objectives

To examine relationships between package insert-derived fraction unbound (Fu-P), study-specific fraction unbound (Fu-S), and SC in critically ill patients receiving CRRT.

Methods

English-language studies containing patient-specific in vivo pharmacokinetic parameters for antimicrobials in critically ill patients requiring CRRT were included. The primary outcome included correlations between Fu-S, Fu-P, and SC. Secondary outcomes included correlations across protein binding quartiles, serum albumin, and predicted in-hospital mortality, and identification of predictors for SC through multivariable analysis.

Results

Eighty-nine studies including 32 antimicrobials were included for analysis. SC was moderately correlated to Fu-S (R2 = 0.55, P &lt; 0.001) and Fu-P (R2 = 0.41, P &lt; 0.001). SC was best correlated to Fu-S in first (&lt;69%) and fourth (&gt;92%) quartiles of fraction unbound and above median albumin concentrations of 24.5 g/L (R2 = 0.71, P = 0.07). Conversely, correlation was weaker in patients with mortality estimates greater than the median of 55% (R2 = 0.06, P = 0.84). SC and Fu-P were also best correlated in the first quartile of antimicrobial fraction unbound (R2 = 0.66, P &lt; 0.001). Increasing Fu-P, flow rate, membrane surface area, and serum albumin, and decreasing physiologic charge significantly predicted increasing SC.

Conclusions

Fu-S and Fu-P were both reasonably correlated to SC. Caution should be taken when using Fu-S to calculate extracorporeal clearance in antimicrobials with 69%–92% fraction unbound or with &gt;55% estimated in-hospital patient mortality. Fu-P may serve as a rudimentary surrogate for SC when Fu-S is unavailable.

Extracorporeal membrane oxygenation combined with continuous renal replacement therapy for the treatment of severe burns: current status and challenges

Severe burns often cause various systemic complications and multiple organ dysfunction syndrome, which is the main cause of death. The lungs and kidneys are vulnerable organs in patients with multiple organ dysfunction syndrome after burns. Extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) have been gradually applied in clinical practice and are beneficial for severe burn patients with refractory respiratory failure or renal dysfunction. However, the literature on ECMO combined with CRRT for the treatment of severe burns is limited. Here, we focus on the current status of ECMO combined with CRRT for the treatment of severe burns and the associated challenges, including the timing of treatment, nutrition support, heparinization and wound management, catheter-related infection and drug dosing in CRRT. With the advancement of medical technology, ECMO combined with CRRT will be further optimized to improve the outcomes of patients with severe burns.

Optimal empiric treatment for KPC-2-producing Klebsiella pneumoniae infections in critically ill patients with normal or decreased renal function using Monte Carlo simulation

BACKGROUND

Limited clinical studies describe the pharmacodynamics of fosfomycin (FOS), tigecycline (TGC) and colistin methanesulfonate (CMS) in combination against KPC-producing Klebsiella pneumoniae (KPC-Kp). Population pharmacokinetic models were used in our study. Monte Carlo simulation was conducted to calculate probability of target attainment (PTA) and cumulative fraction of response (CFR) of each agent alone and in combination against KPC-Kp in patients with normal or decreased renal function.

RESULTS

The simulated regimen of FOS 6 g q8h reached ≥90% PTA against a MIC of 64 mg/L in patients with normal renal function. For patients with renal impairment, FOS 4 g q8h could provide sufficient antimicrobial coverage against a MIC of 128 mg/L. And increasing the daily dose could result to the cut-off value to 256 mg/L in decreased renal function. For TGC, conventional dosing regimens failed to reach 90% PTA against a MIC of 2 mg/L. Higher loading and daily doses (TGC 200/400 mg loading doses followed by 100 mg q12h/200 mg q24h) were needed. For CMS, none achieved 90% PTA against a MIC of 2 mg/L in normal renal function. Against KPC-Kp, the regimens of 200/400 mg loading dose followed by 100 q12h /200 mg q24h achieved > 80% CFRs regardless of renal function, followed by CMS 9 million IU loading dose followed by 4.5/3 million IU q12h in combination with FOS 8 g q8h (CFR 75-91%).

CONCLUSIONS

The use of a loading dose and high daily dose of TGC and CMS in combination with FOS can provide sufficient antimicrobial coverage against critically ill patients infected with KPC-Kp.

Dose Rationale for Amoxicillin in Neonatal Sepsis When Referral Is Not Possible

Background

Despite the widespread use of amoxicillin in young children, efforts to establish the feasibility of simplified dosing regimens in resource-limited settings have relied upon empirical evidence of efficacy. Given the antibacterial profile of beta-lactams, understanding of the determinants of pharmacokinetic variability may provide a more robust guidance for the selection of a suitable regimen. Here we propose a simplified dosing regimen based on pharmacokinetic-pharmacodynamic principles, taking into account the impact of growth, renal maturation and disease processes on the systemic exposure to amoxicillin.

Materials and Methods

A meta-analytical modeling approach was applied to allow the adaptation of an existing pharmacokinetic model for amoxicillin in critically ill adults. Model parameterization was based on allometric concepts, including a maturation function. Clinical trial simulations were then performed to characterize exposure, as defined by secondary pharmacokinetic parameters (AUC, C_max, C_min) and T>MIC. The maximization of the T>MIC was used as criterion for the purpose of this analysis and results compared to current WHO guidelines.

Results

A two-compartment model with first order absorption and elimination was found to best describe the pharmacokinetics of amoxicillin in the target population. In addition to the changes in clearance and volume distribution associated with demographic covariates, our results show that sepsis alters drug distribution, leading to lower amoxicillin levels and longer half-life as compared to non-systemic disease conditions. In contrast to the current WHO guidelines, our analysis reveals that amoxicillin can be used as a fixed dose regimen including two weight bands: 125 mg b.i.d. for patients with body weight < 4.0 kg and 250 mg b.i.d. for patients with body weight ≥ 4.0 kg.

Conclusions

In addition to the effect of developmental growth and renal maturation, sepsis also alters drug disposition. The use of a model-based approach enabled the integration of these factors when defining the dose rationale for amoxicillin. A simplified weight-banded dosing regimen should be considered for neonates and young infants with sepsis when referral is not possible.

What Are the Current Approaches to Optimising Antimicrobial Dosing in the Intensive Care Unit?

Antimicrobial dosing in the intensive care unit (ICU) can be problematic due to various challenges including unique physiological changes observed in critically ill patients and the presence of pathogens with reduced susceptibility. These challenges result in reduced likelihood of standard antimicrobial dosing regimens achieving target exposures associated with optimal patient outcomes. Therefore, the aim of this review is to explore the various methods for optimisation of antimicrobial dosing in ICU patients. Dosing nomograms developed from pharmacokinetic/statistical models and therapeutic drug monitoring are commonly used. However, recent advances in mathematical and statistical modelling have resulted in the development of novel dosing software that utilise Bayesian forecasting and/or artificial intelligence. These programs utilise therapeutic drug monitoring results to further personalise antimicrobial therapy based on each patient’s clinical characteristics. Studies quantifying the clinical and cost benefits associated with dosing software are required before widespread use as a point-of-care system can be justified.

Effective treatment of vancomycin nephrotoxicity with continuous venous-venous haemodiafiltration (CVVHDF) in a paediatric patient

WHAT IS KNOWN AND OBJECTIVE

Vancomycin removal by dialysis uses methods that differ in type of dialysis membrane, dialysis fluxes and duration, ultrafiltration rate and Kt/V_urea (K = dialyser urea clearance, t = time on dialysis and V = total body water) in case of nephrotoxicity. We applied continuous venous-venous haemodiafiltration (CVVHDF) to treat a paediatric case of vancomycin nephrotoxicity caused by high serum trough concentrations.

CASE SUMMARY

We report the case of a 4-year and 7-month-old boy with serum trough concentration of vancomycin of 86.0 mg/L after a 2-day treatment with vancomycin. His serum creatinine increased from 13.3 μmol/L at baseline to 227.0 μmol/L. We discontinued vancomycin and performed a 22-hours CVVHDF with high-flux membrane. Vancomycin decreased by 69.4% (82.1-25.1 mg/L), and renal function improved.

WHAT IS NEW AND CONCLUSION

Therapeutic drug monitoring and laboratory indicator measurements should be performed early during vancomycin treatment in paediatric patients with nephrotoxicity risk factors. Vancomycin removal by CVVHDF can be effective in paediatric acute kidney injury (AKI) associated with vancomycin-associated nephrotoxicity (VAN).

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Serum Concentration of Vancomycin Is a Diagnostic Predictor of Nephrotoxic Acute Kidney Injury in Septic Patients in Clinical and Surgical Wards

Introduction and Aim

There have been few studies to evaluate the monitoring of plasmatic concentrations of vancomycin in septic patients and their association with acute kidney injury (AKI) and death. This study aimed to evaluate the prevalence of adequate, subtherapeutic, and toxic serum concentrations of vancomycin in hospitalized septic patients and to associate the adequacy of therapeutic monitoring with clinical outcomes.

Methodology

This was a cohort-unicentric study that evaluated septic patients aged >18 years using vancomycin admitted to clinical and surgical wards of a Brazilian university center from August 2016 to July 2017 in a daily and uninterrupted way. We excluded patients with AKI prior to the introduction of vancomycin or with AKI development <48 hours after use, patients with AKI of other etiologies, stage V chronic kidney disease, and pregnant women.

Results

We evaluated 225 patients, and 135 were included. Evaluation of serum concentration of vancomycin was realized in 94.1%, and of those, 59.3% presented toxic concentrations. The prevalence of AKI was 27.4% and happened on average on the ninth day of vancomycin usage. Between the fourth and sixth days, vancomycin serum concentration of >21.5 mg/L was a predictor of AKI, with area under the curve of 0.803 (95% CI 0.62-0.98, p=0.005), preceding the diagnosis of AKI by at least 3 days. Of these patients, 20.7% died, and serum concentrations of vancomycin between the fourth and sixth days were identified as risk factors associated with negative outcomes.

Conclusion

Serum concentration of vancomycin is an excellent predictor of AKI in patients admitted to wards, preceding the diagnosis of AKI by at least 72 hours. Toxic concentrations of vancomycin are associated with AKI, and AKI was a risk factor for death. Also, serum concentration of vancomycin >21.5 mg/L was the only variable associated with death in the Cox model.

Drug Dosing in Critically Ill Patients with Acute Kidney Injury and on Renal Replacement Therapy

Acute kidney injury (AKI) complicates in around 40-50% of patients in intensive care units (ICUs), and this can account for up to 80% mortality, especially in those patients requiring renal replacement therapy (RRT). Appropriate drug dosing in such patients is a challenge to the intensivists due to various factors such as patient related (appropriate body weight, organ clearance, serum protein concentration), drug related [molecular weight (MW), protein binding, volume of distribution (V _d), hydrophilicity, or hydrophobicity], and RRT related (type, modality of solute removal, filter characteristics, dose, and duration). Therapeutic drug monitoring (TDM) of drugs can be a promising solution to this complex scenario to titrate a drug to its clinical response, but it is available only for a few drugs. In this review, we discussed drug dosing aspects of antimicrobials, sedatives, and antiepileptics in critically ill patients with AKI on RRT.

How to cite this article

Saran S, Rao NS, Azim A. Drug Dosing in Critically Ill Patients with Acute Kidney Injury and on Renal Replacement Therapy. Indian J Crit Care Med 2020;24(Suppl 3):S129-S134.

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.

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.

Vancomycin Removal During High-Volume Peritoneal Dialysis in Acute Kidney Injury Patients: A Prospective Cohort Clinical Study

Introduction

Vancomycin pharmacokinetic data in patients with acute kidney injury (AKI) on high-volume peritoneal dialysis (HVPD) are lacking. The aims were to study the pharmacokinetics of i.v. vancomycin in patients with AKI treated by HVPD who received an i.v. dose of vancomycin (15–20 mg/kg), to determine the vancomycin removal, and to establish vancomycin dosing and evaluation pharmacokinetics target attainment achievement for the empirical treatment of patients with AKI treated by HVPD.

Methods

Vancomycin was administered 1 hour before dialysis start. Samples of all dialysate were collected for a 24-hour period. Blood samples were collected after 1, 2, 4, and 24 hours of therapy. Vancomycin concentrations were determined using a liquid chromatographic (high-performance liquid chromatography)–fluorescence method. Pharmacokinetic calculations were completed assuming a 1-compartment model.

Results

Ten patients completed the study. The mean vancomycin dose administered was 18.0 ± 2.95 mg/kg (14.7–21.8 mg/kg) on the day of study (first day) and the mean percentage of vancomycin removal by HVPD was 21.7% ± 2.2% (16%–29%). Peritoneal clearance was 8.1 ± 2.2 ml/min (5.3–12 ml/min). The serum vancomycin half-life was 71.2 ± 24.7 hours (42–110 hours) during HVPD session, the maximum serum concentration was 26.2 ± 3.5 mg/l, which occurred 1 hour after vancomycin administration and HVPD start. Area under the curve (AUC)0–24/minimum inhibitory concentration (MIC) ratio ≥400 was achieved in all patients when MIC = 1 mg/l was considered.

Conclusion

HVPD removes considerable amounts of vancomycin in septic patients with AKI. Administration of 18 mg/kg vancomycin each 48 to 72 hours in patients with AKI undergoing HVPD was required to reach and maintain therapeutic concentrations.

Antimicrobial Activity and Resistance: Influencing Factors

Rational use of antibiotic is the key approach to improve the antibiotic performance and tackling of the antimicrobial resistance. The efficacy of antimicrobials are influenced by many factors: (1) bacterial status (susceptibility and resistance, tolerance, persistence, biofilm) and inoculum size; (2) antimicrobial concentrations [mutant selection window (MSW) and sub-inhibitory concentration]; (3) host factors (serum effect and impact on gut micro-biota). Additional understandings regarding the linkage between antimicrobial usages, bacterial status and host response offers us new insights and encourage the struggle for the designing of antimicrobial treatment regimens that reaching better clinical outcome and minimizing the emergence of resistance at the same time.

Pharmacokinetics and pharmacodynamics of antibiotics in critically ill acute kidney injury patients

Sepsis is the most common cause of death in critically ill patients and is associated with multiorgan failure, including acute kidney injury (AKI). This situation can require acute renal support and increase mortality. Therefore, it is essential to administer antimicrobials in doses that achieve adequate serum levels, avoiding both overdosing and drug toxicity as well as underdosing and the risk of antibiotic resistance and higher mortality. Currently, there are no validated guidelines on antibiotic dose adjustments in septic patients with AKI. The current recommendations were extrapolated from studies conducted in noncritical patients with end‐stage chronic kidney disease receiving chronic renal replacement therapy. This study aimed to review and discuss the complexity of this issue, considering several factors related to drug metabolism, the characteristics of critically ill patients, the properties of antimicrobial drugs and dialysis methods.