The influence of acute kidney injury on antimicrobial dosing in critically ill patients: are dose reductions always necessary?

Linezolid dosing in critically ill patients undergoing various modalities of renal replacement therapy: a pooled population pharmacokinetic analysis

The altered pharmacokinetics (PK) of linezolid are pronounced in critically ill patients undergoing different modalities of renal replacement therapy (RRT). This study aimed to provide a pooled population PK analysis of linezolid in patients undergoing RRT, and to evaluate the pharmacodynamic target attainment of linezolid standard dosing (600 mg q12h). In total, 414 pooled linezolid concentration observations from 69 patients undergoing intermittent haemodialysis (IHD), sustained low-efficiency dialysis (SLED) or continuous RRT were used to develop the population PK model. The probability of target attainment (PTA) for the efficacy markers of 85% T>minimum inhibitory concentration (MIC) and area under the concentration-time curve (AUC)/MIC >100 was evaluated, and the risk of toxicity was estimated based on Cmin ≥10 mg/L. Linezolid concentration data were described adequately by a two-compartment model. Renal function and body weight were identified as significant modifiers for endogenous clearance of linezolid. Simulations demonstrated that the PTA of 85% T>MIC and AUC/MIC>100 was unacceptably low (0-58.6%, MIC ≥1 mg/L) in RRT patients with preserved renal function, while desirable 85% T>MIC attainment (≥ 90%, MIC ≤2 mg/L) was achieved in anuric RRT patients. The predicted risk of toxicity was negligible (<1.0%) in patients with preserved renal function (regardless of RRT modality), while the probability of reaching Cmin ≥10 mg/L was high (17.9-20.9%) for the anuric patient population undergoing IHD or SLED. In conclusion, standard linezolid dosing is adequate for anuric RRT patients with MIC ≤2 mg/L.

Optimization of antimicrobial dosing in patients with acute kidney injury: a single-centre observational study

Background

Acute kidney injury (AKI) is a potential complication of systemic infection. Optimizing antimicrobial dosing in this dynamic state can be challenging with sub- or supra-therapeutic dosing risking treatment failure or toxicity, respectively. Locally, unadjusted renal dosing for the first 48 h of infection is recommended.

Objectives

To determine the outcomes associated with this dosing strategy.

Methods

A retrospective cohort analysis was undertaken in patients treated for Gram-negative bacteraemia with concurrent non-filtration dependent AKI from a single-centre NHS acute hospital (April 2016–March 2020). Patient demographics, microbiology data, antimicrobial treatment and patient outcome (in-hospital mortality and kidney function) were analysed.

Results

In total, 647 episodes of Gram-negative bacteraemia (608 patients) were included; 305/608 (50.2%) were male with median age 71 years (range 18–100). AKI was present in 235/647 (36.3%); 78/647 (12.1%) and 45/647 (7.0%) having Kidney Disease Improving Global Outcomes-defined injury (stage 2) or failure (stage 3), respectively. In-hospital 30 day mortality was 25/352 (7.1%), 14/112 (12.5%), 26/123 (21.1%) and 11/60(18.3%) in patients with normal renal function, AKI stage 1, AKI stage ≥2 and established chronic kidney disease, respectively. Recovery of renal function at Day 21 or discharge was present in 105/106 surviving patients presenting with AKI stage ≥2. Time to recovery of AKI was similar in patients receiving full, low or no aminoglycoside (3 versus 4 versus 3 days, P = 0.612) and those receiving full- and low-dose β-lactam (3 versus 5 days, P = 0.077).

Conclusions

There is a high burden of AKI in patients with Gram-negative bacteraemia. Dose adjustments of β-lactams may not be necessary in the first 48 h of infection-induced AKI and single-dose aminoglycosides may be considered for early empirical coverage.

Clinical practice guidelines for therapeutic drug monitoring of teicoplanin: a consensus review by the Japanese Society of Chemotherapy and the Japanese Society of Therapeutic Drug Monitoring

Background

Owing to its low risk of adverse effects, teicoplanin has been extensively used in patients with infections caused by MRSA. To promote the better management of patients receiving teicoplanin, we have updated the guidelines for therapeutic drug monitoring (TDM).

Methods

The guidelines were developed by a committee following the methodology handbook published by the Japanese Medical Information Distribution Service. Nine clinical questions were selected. The committee conducted a systematic review and meta-analysis to establish evidence-based recommendations for the target trough concentration (C_min). An initial electronic database search returned 515 articles, and 97 articles qualified for a full review. Four and five studies were included for the efficacy evaluation of cut-off C_min values of 15 and 20 mg/L, respectively.

Results

Compared with C_min < 15 mg/L, a target C_min value of 15–30 mg/L resulted in increased clinical efficacy in patients with non-complicated MRSA infections (OR = 2.68; 95% CI = 1.14–6.32) without an increase in adverse effects. Although there was insufficient evidence, target C_min values of 20–40 mg/L were suggested in patients with complicated or serious MRSA infections. A 3 day loading regimen followed by maintenance treatment according to renal function was recommended to achieve the target trough concentrations. Because of the prolonged half-life of teicoplanin, measurement of the C_min value on Day 4 before reaching steady state was recommended.

Conclusions

The new guideline recommendations indicate the target C_min value for TDM and the dosage regimen to achieve this concentration and suggest practices for specific subpopulations.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Initial antimicrobial management of sepsis

Sepsis is a common consequence of infection, associated with a mortality rate > 25%. Although community-acquired sepsis is more common, hospital-acquired infection is more lethal. The most common site of infection is the lung, followed by abdominal infection, catheter-associated blood steam infection and urinary tract infection. Gram-negative sepsis is more common than gram-positive infection, but sepsis can also be due to fungal and viral pathogens. To reduce mortality, it is necessary to give immediate, empiric, broad-spectrum therapy to those with severe sepsis and/or shock, but this approach can drive antimicrobial overuse and resistance and should be accompanied by a commitment to de-escalation and antimicrobial stewardship. Biomarkers such a procalcitonin can provide decision support for antibiotic use, and may identify patients with a low likelihood of infection, and in some settings, can guide duration of antibiotic therapy. Sepsis can involve drug-resistant pathogens, and this often necessitates consideration of newer antimicrobial agents.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members.As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Evaluation of pharmacokinetic and pharmacodynamic parameters of meropenem in critically ill patients with acute kidney disease

Purpose

No study has been evaluated pharmacokinetic (PK) and pharmacodynamic (PD) properties of β-lactam antibiotics in patients with acute kidney injury (AKI), not requiring renal replacement therapy (RRT). We evaluated the time that plasma concentrations remain above four times the MIC (ft > 4MIC) and PK parameters of meropenem in this population.

Methods

In this prospective, randomized clinical trial (RCT), all patients received standard dose (3 g daily) of meropenem for 48 h, then randomly allocated in standard or adjusted groups. The standard group received meropenem without dose adjustment. In the adjusted group, the meropenem dose was adjusted based on the Cockcroft-Gault(C-G) equation. Meropenem concentrations were measured at the peak and trough times on the 2nd and 5th days of the study.

Results

On the 2nd day of the study, 3 out of 10 (30%) of patients attained the PD target (≥ 80%ft > 4MIC). In the 5th day of the study, the PD target was attained in 2 out of 10 (20%) and 1 out of 5 (20%) of patients who received standard and adjusted doses of meropenem, respectively (p = 1). In all samples, increased volume of distribution (Vd) (median; IQR) (46.04; 23.06–103.18 L), terminal half-life (T1/2) (4.51; 2.67–8.88 h) and decreased clearance (6.52; 4.43–10.16 L/h) have been shown.

Conclusion

In critically ill patients with AKI, who not receive RRT, standard doses, and adjusted according to renal function of meropenem failed to achieve PD target of ≥ 80%ft > 4MIC. Higher doses are required for this target.

Retrospectively registered

The study protocol with registered retrospectively and approved on January 19, 2019, with the number of IRCT20160412027346N5.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00228-020-03062-0.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members. As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Drug dosing in cancer patients with decreased kidney function: A practical approach

Correct drug dosing of anticancer agents is essential to obtain optimal outcomes. Overdosing will result in increased toxicity, treatment interruption and possible cessation of anticancer treatment. Underdosing may result in suboptimal anti-cancer effects and may increase the risk of cancer-related mortality. As it is practical nor feasible to perform therapeutic drug monitoring for all anti-cancer drugs, kidney function is used to guide drug dosing for those drugs whose primary mode of excretion is through the kidney. However, it is not well-established what method should be utilized to measure or estimate kidney function and the choice of method does influence treatment decisions regarding eligibility for anti-cancer drugs and their dose. In this review, we will provide an overview regarding the importance of drug dosing, the preferred method to determine kidney function and a practical approach to drug dosing of anticancer drugs.

Aminoglycoside Dosing and Volume of Distribution in Critically Ill Surgery Patients

Background: At a tertiary referral and Level I trauma center, current institutional guidelines suggest initial aminoglycoside doses of gentamicin or tobramycin 4 mg/kg and amikacin 16 mg/kg for patients admitted to surgical intensive care units (SICUs) with suspected gram-negative infection. The objective of this study was to evaluate initial aminoglycoside dosing and peak serum drug concentrations in critically ill surgery patients to characterize the aminoglycoside volume of distribution (V_d) and determine an optimal standardized dosing strategy. Methods: This retrospective, observational, single-center study included adult SICU patients who received an aminoglycoside for additional gram-negative coverage. Descriptive statistics were used to evaluate the patient population, aminoglycoside dosing, and V_d. Multivariable linear regression was applied to determine variables associated with greater aminoglycoside V_d. The mortality rate was compared in patients who achieved adequate initial peak concentrations versus those who did not. Results: One hundred seventeen patients received an aminoglycoside in the SICUs, of whom 58 had an appropriately timed peak concentration measurement. The mean Acute Physiology, Age, and Chronic Health Evaluation (APACHE) II score was 27.8 ± 8.9. The V_d in patients receiving gentamicin, tobramycin, and amikacin was 0.49 ± 0.10, 0.41 ± 0.09, and 0.53 ± 0.13 L/kg, respectively. Together, the mean aminoglycoside V_d was 0.50 ± 0.12 L/kg. Gentamicin or tobramycin 5 mg/kg achieved goal peak concentrations in 24 patients (63.2%), and amikacin 20 mg/kg achieved the desired concentrations in nine patients (50.0%). Net fluid status, Body Mass Index, and vasopressor use were not predictive of V_d. There was no difference in the in-hospital mortality rate in patients who achieved adequate peak concentrations versus those who did not (26.8% versus 26.7%; p = 0.99). Conclusion: High aminoglycoside doses are needed in critically ill surgery patients to achieve adequate initial peak concentrations because of the high V_d. Goal peak concentrations were optimized at doses of gentamicin or tobramycin 5 mg/kg, and amikacin 20 mg/kg.

Bloodstream infections in critically ill patients: an expert statement

Bloodstream infection (BSI) is defined by positive blood cultures in a patient with systemic signs of infection and may be either secondary to a documented source or primary—that is, without identified origin. Community-acquired BSIs in immunocompetent adults usually involve drug-susceptible bacteria, while healthcare-associated BSIs are frequently due to multidrug-resistant (MDR) strains. Early adequate antimicrobial therapy is a key to improve patient outcomes, especially in those with criteria for sepsis or septic shock, and should be based on guidelines and direct examination of available samples. Local epidemiology, suspected source, immune status, previous antimicrobial exposure, and documented colonization with MDR bacteria must be considered for the choice of first-line antimicrobials in healthcare-associated and hospital-acquired BSIs. Early genotypic or phenotypic tests are now available for bacterial identification and early detection of resistance mechanisms and may help, though their clinical impact warrants further investigations. Initial antimicrobial dosing should take into account the pharmacokinetic alterations commonly observed in ICU patients, with a loading dose in case of sepsis or septic shock. Initial antimicrobial combination attempting to increase the antimicrobial spectrum should be discussed when MDR bacteria are suspected and/or in the most severely ill patients. Source identification and control should be performed as soon as the hemodynamic status is stabilized. De-escalation from a broad-spectrum to a narrow-spectrum antimicrobial may reduce antibiotic selection pressure without negative impact on mortality. The duration of therapy is usually 5–8 days though longer durations may be discussed depending on the underlying illness and the source of infection. This narrative review covers the epidemiology, diagnostic workflow and therapeutic aspects of BSI in ICU patients and proposed up-to-date expert statements.

Increased Arbekacin Clearance in Patients With Febrile Neutropenia

BACKGROUND

Arbekacin (ABK) is used to treat infections caused by methicillin-resistant Staphylococcus aureus and is used widely for the treatment of febrile neutropenia (FN). As ABK has a narrow therapeutic concentration window, the dosage must be adjusted via therapeutic drug monitoring. However, the influence of the physiology of patients with FN on the pharmacokinetic (PK) parameters of ABK remains unclear. Therefore, we examined this influence on ABK PK parameters.

METHOD

We performed a retrospective cohort study using data from patients with a hematologic malignancy who were ≥18 years and had been administered ABK. We excluded patients who did not receive therapeutic drug monitoring and had an estimated glomerular filtration rate (eGFR) of <30 mL/min, because clinically sufficient data would not be available.

RESULT

Of the 99 enrolled patients, 25 did not have FN and 74 had FN. Arbekacin clearance (CLabk) was shown to correlate with eGFR in patients with FN (r = 0.32, P = 0.0062) and without FN (r = 0.50, P = 0.01). CLabk was higher in patients with FN than in those without FN. In addition, in the eGFR of <100 mL/min group (normal renal function), CLabk and CLabk/eGFR were also higher in patients with FN than in those without FN.

CONCLUSIONS

CLabk was increased in patients with FN and normal renal function; therefore, we propose an increased ABK dose for patients with FN and normal renal function.

Vancomycin Removal During High-Volume Peritoneal Dialysis in Acute Kidney Injury Patients

Studies on vancomycin pharmacokinetics in acute kidney injury (AKI) patients on high-volume peritoneal dialysis (HVPD) are lacking. We studied the pharmacokinetics of intravenous (IV) vancomycin in AKI patients treated by HVPD who received a prescribed single IV dose of vancomycin (15 - 20 mg/kg total body weight) to determine the extent of vancomycin removal and to establish vancomycin dosing guidelines for the empirical treatment of AKI patients receiving HVPD. The application of 18 mg/kg vancomycin every 48 - 72 hours in AKI patients undergoing HVPD was required to maintain therapeutic concentrations.

Intensive multidisciplinary management in critical care patients affected by severe necrotizing soft tissue infections: a cooperative method to improve the efficacy of treatment

To illustrate the effectiveness of our intensive multidisciplinary management (IMM) in the treatment of severely ill patients with necrotizing soft tissue infections (NSTIs). A retrospective observational study was conducted in a general ICU. Thirty-two consecutive patients undergoing IMM were carefully compared with 30 consecutive patients receiving a standard management (SM). IMM combined intensive care management, early surgical debridement followed by daily inspection of surgical wounds, close microbiological surveillance, and targeted high-dose antibiotics. IMM was associated with the better decrease of daily SOFA score (p = 0.04). Also, IMM caused + 12% increase in the overall number of surgical procedures (p = 0.022) and a higher number of tissue biopsies/per day (median 0.63 versus 0.32; p = 0.025), leading to a more targeted antimicrobial changes (89.6% vs 51.6%; p < 0.00001). High-dose daptomycin (75% vs 36.7%; p = 0.002) and extended/continuous infusion of beta-lactams (75% vs 43.3%; p = 0.011) were more frequently utilized. A specific efficiency score correlated with the decrease of SOFA score (efficacy) in IMM patients only (p = 0.027). Finally, IMM was associated with a significant lower ICU mortality rate (15.6% vs 40%; p = 0.032). IMM was more effective than SM as it allowed the earlier control of infection and the faster reduction of multiple organ-dysfunction.

Challenges in the management of septic shock: a narrative review

While guidelines provide important information on how to approach a patient in septic shock, "many challenges remain" for the management of these patients. In this narrative review, the panel discusses the challenges in identifying the right hemodynamic target, optimization of fluid therapy, selection of vasopressor agents, identification of patients who may benefit from inotropic agents or on the contrary beta-blockade, and use of steroids. The place for microcirculation-targeted therapy is debated as well as the use of alternative techniques (blood purification) and therapies (vitamin C). The implications of hemodynamic alterations on antibiotic doses is discussed. Finally, the specific challenges in low- and middle-income countries are addressed. Ongoing trials address some of these challenges, but many uncertainties will remain, and individualized therapies based on careful clinical assessment will continue to be essential to optimizing the care of patients with septic shock.

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.

Pharmacokinetics-pharmacodynamics issues relevant for the clinical use of beta-lactam antibiotics in critically ill patients

Antimicrobials are among the most important and commonly prescribed drugs in the management of critically ill patients and beta-lactams are the most common antibiotic class used. Critically ill patient's pathophysiological factors lead to altered pharmacokinetics and pharmacodynamics of beta-lactams.A comprehensive bibliographic search in PubMed database of all English language articles published from January 2000 to December 2017 was performed, allowing the selection of articles addressing the pharmacokinetics or pharmacodynamics of beta-lactam antibiotics in critically ill patients.In critically ill patients, several factors may increase volume of distribution and enhance renal clearance, inducing high intra- and inter-patient variability in beta-lactam concentration and promoting the risk of antibiotic underdosing. The duration of infusion of beta-lactams has been shown to influence the fT > minimal inhibitory concentration and an improved beta-lactam pharmacodynamics profile may be obtained by longer exposure with more frequent dosing, extended infusions, or continuous infusions.The use of extracorporeal support techniques in the critically ill may further contribute to this problem and we recommend not reducing standard antibiotic dosage since no drug accumulation was found in the available literature and to maintain continuous or prolonged infusion, especially for the treatment of infections caused by multidrug-resistant bacteria.Prediction of outcome based on concentrations in plasma results in overestimation of antimicrobial activity at the site of infection, namely in cerebrospinal fluid and the lung. Therefore, although no studies have assessed clinical outcome, we recommend using higher than standard dosing, preferably with continuous or prolonged infusions, especially when treating less susceptible bacterial strains at these sites, as the pharmacodynamics profile may improve with no apparent increase in toxicity.A therapeutic drug monitoring-guided approach could be particularly useful in critically ill patients in whom achieving target concentrations is more difficult, such as obese patients, immunocompromised patients, those infected by highly resistant bacterial strains, patients with augmented renal clearance, and those undergoing extracorporeal support techniques.

Successful Treatment of PD Peritonitis Due to Brevundimonas vesicularis

Brevundimonas vesicularis is a rare cause of peritoneal dialysis-associated peritonitis (PD peritonitis). One documented case report described poor outcome despite treatment with appropriate antibiotics. Here, we report the successful treatment of PD peritonitis due to Brevundimonas vesicularis with 21 days of intraperitoneal (IP) antibiotics using the regimen described for Pseudomonas aeruginosa, notably IP gentamicin (10 days) followed by IP cefepime and oral ciprofloxacin (11 days). Despite the favorable outcome, measurement of antibiotic concentrations in the PD effluent suggests that the cefepime and possibly ciprofloxacin regimens do not achieve key antibiotic concentration targets that are reported to maximize bacterial kill. The role of routine therapeutic drug monitoring to maximize clinical outcomes from antibiotic therapy for PD peritonitis requires further consideration.

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.

Clinical Pharmacokinetics in Kidney Disease: Fundamental Principles

Kidney disease is an increasingly common comorbidity that alters the pharmacokinetics of many drugs. Prescribing to patients with kidney disease requires knowledge about the drug, the extent of the patient's altered physiology, and pharmacokinetic principles that influence the design of dosing regimens. There are multiple physiologic effects of impaired kidney function, and the extent to which they occur in an individual at any given time can be difficult to define. Although some guidelines are available for dosing in kidney disease, they may be on the basis of limited data or not widely applicable, and therefore, an understanding of pharmacokinetic principles and how to apply them is important to the practicing clinician. Whether kidney disease is acute or chronic, drug clearance decreases, and the volume of distribution may remain the same or increase. Although in CKD, these changes progress relatively slowly, they are dynamic in AKI, and recovery is possible depending on the etiology and treatments. This, and the use of kidney replacement therapies further complicate attempts to quantify drug clearance at the time of prescribing and dosing in AKI. The required change in the dosing regimen can be estimated or even quantitated in certain instances through the application of pharmacokinetic principles to guide rational drug dosing. This offers an opportunity to provide personalized medical care and minimizes adverse drug events from either under- or overdosing. We discuss the principles of pharmacokinetics that are fundamental for the design of an appropriate dosing regimen in this review.

Optimisation of antimicrobial dosing based on pharmacokinetic and pharmacodynamic principles

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

Population Pharmacokinetics of Piperacillin in Sepsis Patients: Should Alternative Dosing Strategies Be Considered?

Sufficient antibiotic dosing in septic patients is essential for reducing mortality. Piperacillin-tazobactam is often used for empirical treatment, but due to the pharmacokinetic (PK) variability seen in septic patients, optimal dosing may be a challenge. We determined the PK profile for piperacillin given at 4 g every 8 h in 22 septic patients admitted to a medical ward. Piperacillin concentrations were compared to the clinical breakpoint MIC for Pseudomonas aeruginosa (16 mg/liter), and the following PK/pharmacodynamic (PD) targets were evaluated: the percentage of the dosing interval that the free drug concentration is maintained above the MIC (fTMIC) of 50% and 100%. A two-compartment population PK model described the data well, with clearance being divided into renal and nonrenal components. The renal component was proportional to the estimated creatinine clearance (eCLCR) and constituted 74% of the total clearance in a typical individual (eCLCR, 83.9 ml/min). Patients with a high eCLCR (>130 ml/min) were at risk of subtherapeutic concentrations for the current regimen, with a 90% probability of target attainment being reached at MICs of 2.0 (50% fTMIC) and 0.125 mg/liter (100% fTMIC). Simulations of alternative dosing regimens and modes of administration showed that dose increment and prolonged infusion increased the chance of achieving predefined PK/PD targets. Alternative dosing strategies may therefore be needed to optimize piperacillin exposure in septic patients. (This study has been registered at ClinicalTrials.gov under identifier NCT02569086.).

Population Pharmacokinetics of Meropenem in Plasma and Subcutis from Patients on Extracorporeal Membrane Oxygenation Treatment

The objectives of this study were to describe meropenem pharmacokinetics (PK) in plasma and/or subcutaneous adipose tissue (SCT) in critically ill patients receiving extracorporeal membrane oxygenation (ECMO) treatment and to develop a population PK model to simulate alternative dosing regimens and modes of administration. We conducted a prospective observational study. Ten patients on ECMO treatment received meropenem (1 or 2 g) intravenously over 5 min every 8 h. Serial SCT concentrations were determined using microdialysis and compared with plasma concentrations. A population PK model of SCT and plasma data was developed using NONMEM. Time above clinical breakpoint MIC for Pseudomonas aeruginosa (8 mg/liter) was predicted for each patient. The following targets were evaluated: time for which the free (unbound) concentration is maintained above the MIC of at least 40% (40% fT>MIC), 100% fT>MIC, and 100% fT>4×MIC. For all dosing regimens simulated in both plasma and SCT, 40% fT>MIC was attained. However, prolonged meropenem infusion would be needed for 100% fT>MIC and 100% fT>4×MIC to be obtained. Meropenem plasma and SCT concentrations were associated with estimated creatinine clearance (eCL_Cr). Simulations showed that in patients with increased eCL_Cr, dose increment or continuous infusion may be needed to obtain therapeutic meropenem concentrations. In conclusion, our results show that using traditional targets of 40% fT>MIC for standard meropenem dosing of 1 g intravenously every 8 h is likely to provide sufficient meropenem concentration to treat the problematic pathogen P. aeruginosa for patients receiving ECMO treatment. However, for patients with an increased eCL_Cr, or if more aggressive targets, like 100% fT>MIC or 100% fT>4×MIC, are adopted, incremental dosing or continuous infusion may be needed.

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.

The Clinical Epidemiology and 30-Day Outcomes of Emergency Department Patients With Acute Kidney Injury

BACKGROUND

Acute kidney injury (AKI) is associated with increased mortality and dialysis in hospitalized patients but has been little explored in the emergency department (ED) setting.

OBJECTIVE

The objective of this study was to describe the risk factors, prevalence, management, and outcomes in the ED population, and to identify the proportion of AKI patients who were discharged home with no renal-specific follow-up.

DESIGN

This is a retrospective cohort study using administrative and laboratory databases.

SETTING

Two urban EDs in Vancouver, British Columbia, Canada.

PATIENTS

We included all unique ED patients over a 1-week period.

METHODS

All patients had their described demographics, comorbidities, medications, laboratory values, and ED treatments collected. AKI was defined pragmatically, based upon accepted guidelines. The cohort was then probabilistically linked to the provincial renal database to ascertain renal replacement (transplant or dialysis) and the provincial vital statistics database to obtain mortality. The primary outcome was the prevalence of AKI; secondary outcomes included (1) the proportion of AKI patients who were discharged home with no renal-specific follow-up and (2) the combined 30-day rate of death or renal replacement among AKI patients.

RESULTS

There were 1651 ED unique patients, and 840 had at least one serum creatinine (SCr) obtained. Overall, 90 patients had AKI (10.7% of ED patients with at least one SCr, 95% confidence interval [CI], 8.7%-13.1%; 5.5% of all ED patients, 95% CI, 4.4%-6.7%) with a median age of 74 and 70% male. Of the 31 (34.4%) AKI patients discharged home, 4 (12.9%) had renal-specific follow-up arranged in the ED. Among the 90 AKI patients, 11 died and none required renal replacement at 30 days, for a combined outcome of 12.2% (95% CI, 6.5%-21.2%).

LIMITATIONS

Sample sizes may be small. Nearly half of ED patients did not obtain an SCr. Many patients did not have sequential SCr testing, and a modified definition of AKI was used.

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.

High target attainment for β-lactam antibiotics in intensive care unit patients when actual minimum inhibitory concentrations are applied

Patients in the intensive care unit (ICU) are at risk for suboptimal levels of β-lactam antibiotics, possibly leading to poor efficacy. Our aim was to investigate whether the actual minimum inhibitory concentration (MIC) compared to the more commonly used arbitrary epidemiological cut-off values (ECOFFs) would affect target attainment in ICU patients on empirical treatment with broad-spectrum β-lactam antibiotics and to identify risk factors for not reaching target. In a prospective, multicenter study, ICU patients ≥18 years old and treated with piperacillin/tazobactam, meropenem, or cefotaxime were included. Clinical and laboratory data were recorded. Serum trough antibiotic levels from three consecutive days were analyzed by liquid chromatography-mass spectrometry (LC-MS). The target was defined as the free trough concentration above the MIC (100% fT_>MIC). MIC_ECOFF was used as the target and, when available, the actual MIC (MIC_ACTUAL) was applied. The median age of the patients was 70 years old, 52% (58/111) were males, and the median estimated glomerular filtration rate (eGFR) was 48.0 mL/min/1.73 m². The rate of patients reaching 100% fT > MIC_ACTUAL was higher (89%, 31/35) compared to the same patients using MIC_ECOFF (60%, p = 0.002). In total, 55% (61/111) reached 100% fT > MIC_ECOFF. Increased renal clearance was independently associated to not reaching 100% fT > MIC_ECOFF. On repeated sampling, >77% of patients had stable serum drug levels around the MIC_ECOFF. Serum concentrations of β-lactam antibiotics vary extensively between ICU patients. The rate of patients not reaching target was markedly lower for the actual MIC than when the arbitrary MIC based on the ECOFF was used, which is important to consider in future studies.

Penicillin G Treatment in Infective Endocarditis Patients - Does Standard Dosing Result in Therapeutic Plasma Concentrations?

Penicillin G is frequently used to treat infective endocarditis (IE) caused by streptococci, penicillin-susceptible staphylococci and enterococci. Appropriate antibiotic exposure is essential for survival and reduces the risk of complications and drug resistance development. We determined penicillin G plasma concentration [p-penicillin] once weekly in 46 IE patients. The aim was to evaluate whether penicillin G 3 g every 6 hr (q6 h) resulted in therapeutic concentrations and to analyse potential factors that influence inter- and intra-individual variability, using linear regression and a random coefficient model. [P-penicillin] at 3 hr and at 6 hr was compared with the minimal inhibitory concentration (MIC) of the bacteria isolated from blood cultures to evaluate the following PK/PD targets: 50% fT > MIC and 100% fT > MIC. [P-penicillin] varied notably between patients and was associated with age, weight, p-creatinine and estimated creatinine clearance (eCLcr). Additionally, an increase in [p-penicillin] during the treatment period showed strong correlation with age, a low eCLcr, a low weight and a low p-albumin. Of the 46 patients, 96% had [p-penicillin] that resulted in 50% fT > MIC, while 71% had [p-penicillin] resulting in 100% fT > MIC. The majority of patients not achieving the 100% fT > MIC target were infected with enterococci. Streptococci and staphylococci isolated from blood cultures were highly susceptible to penicillin G. Our results suggest that penicillin G 3 g q6 h is suitable to treat IE caused by streptococci and penicillin-susceptible staphylococci, but caution must be taken when the infection is caused by enterococci. When treating enterococci, therapeutic drug monitoring should be applied to optimize penicillin G dosing and exposure.

Change of teicoplanin loading dose requirement for incremental increases of systemic inflammatory response syndrome score in the setting of sepsis

Background Target trough concentrations are recommended for teicoplanin (TEIC) to minimize its adverse effects and to maximize efficacy in sepsis caused by grampositive cocci, including methicillin-resistant Staphylococcus aureus infection. However, optimal doses to attain proper trough values in patients with sepsis have not yet been well established for TEIC. Objective This study investigated whether the systemic inflammatory response syndrome (SIRS) score could predict the pharmacokinetics of TEIC in patients with sepsis. Setting This study was conducted at Fukuoka University Hospital in Japan. Methods We retrospectively reviewed the records of patients using TEIC between April 2012 and March 2015. SIRS positive was defined as infection with a SIRS score ≥2. Estimates of pharmacokinetic parameters were calculated using a Bayesian method. Creatinine clearance rates were estimated by the Cockcroft-Gault formula (eCcr). Main outcome measure Change of TEIC loading dose requirement for incremental increases of SIRS score. Results In total, 133 patients were enrolled: 50 non-SIRS patients and 83 patients with SIRS. The TEIC plasma trough concentration was significantly lower in SIRS than non-SIRS patients (15.7 ± 7.1 vs. 20.1 ± 8.6 μg/mL; P < 0.01), although there was no significant difference in the loading dose administered. Moreover, SIRS scores were increasingly predictive of eCcr and TEIC clearance in a stepwise manner. To achieve the target trough concentration (15-30 μg/mL), the optimal doses required in non-SIRS versus SIRS patients were 12-24 versus 18-30 mg/kg/day, respectively, during the first 48 h. Conclusions These findings suggest that the pharmacokinetics of TEIC are altered in SIRS patients, who required higher doses than non-SIRS patients to achieve the target trough concentration. We suggest that the SIRS score can become a new modality to determine the initial TEIC loading dose.

Personalised beta-lactam therapy: basic principles and practical approach

Bacterial infections are potentially life-threatening diseases requiring effective antibiotic treatment right from the outset to achieve a favourable prognosis. Therapeutic success depends on the susceptibility of the bacterial pathogen, determined by the minimum inhibitory concentration (MIC), and the concentration of the antibiotic at the focus of infection, which is influenced by drug metabolism and pharmacokinetic (PK) factors. Beta-lactams are time-dependent antibiotics. Bacterial killing correlates with the duration of the drug concentration above the MIC of the pathogen. Critical illness is associated with major PK changes. This may lead to unexpected drug concentrations and unpredictable dose requirements differing significantly from standard dosages. Emerging dosing strategies are therefore based on PK/pharmacodynamic (PD) principles. Therapeutic drug monitoring (TDM) is increasingly playing a key role in antibiotic treatment optimisation in general and in beta-lactam therapy, in particular, notably in severely ill patients. Furthermore, evidence of the superiority of continuous beta-lactam infusions over shorter administration regimens is growing. Target drug concentrations have to be defined, considering MIC values especially in pathogens with limited susceptibility. For reliable TDM results, correct pre-analytical sample handling is indispensable. Personalised, TDM-guided therapy currently offers the most promising approach to assuring that beta-lactam treatment is effective, especially in critically ill patients.

Population pharmacokinetics of piperacillin in the early phase of septic shock: does standard dosing result in therapeutic plasma concentrations?

Antibiotic dosing in septic shock patients poses a challenge for clinicians due to the pharmacokinetic (PK) variability seen in this patient population. Piperacillin-tazobactam is often used for empirical treatment, and initial appropriate dosing is crucial for reducing mortality. Accordingly, we determined the pharmacokinetic profile of piperacillin (4 g) every 8 h, during the third consecutive dosing interval, in 15 patients treated empirically for septic shock. We developed a population pharmacokinetic model to assess empirical dosing and to simulate alternative dosing regimens and modes of administration. Time above the MIC (T>MIC) predicted for each patient was evaluated against clinical breakpoint MIC for Pseudomonas aeruginosa (16 mg/liter). Pharmacokinetic-pharmacodynamic (PK/PD) targets evaluated were 50% fT>4×MIC and 100% fT>MIC. A population PK model was developed using NONMEM, and data were best described by a two-compartment model. Central and intercompartmental clearances were 3.6 liters/h (relative standard error [RSE], 15.7%) and 6.58 liters/h (RSE, 16.4%), respectively, and central and peripheral volumes were 7.3 liters (RSE, 11.8%) and 3.9 liters (RSE, 9.7%), respectively. Piperacillin plasma concentrations varied considerably between patients and were associated with levels of plasma creatinine. Patients with impaired renal function were more likely to achieve predefined PK/PD targets than were patients with preserved or augmented renal function. Simulations of alternative dosing regimens showed that frequent intermittent bolus dosing as well as dosing by extended and continuous infusion increases the probability of attaining therapeutic plasma concentrations. For septic shock patients with preserved or augmented renal function, dose increment or prolonged infusion of the drug needs to be considered. (This study has been registered at ClinicalTrials.gov under registration no. NCT02306928.).

Evaluation of a protocol for vancomycin administration in critically patients with and without kidney dysfunction

BACKGROUND

Administration of vancomycin in critically ill patients needs close regulation. While subtherapeutical vancomycin serum concentration (VSC) is associated with increased mortality, accumulation is responsible for nephrotoxicity. Our study aimed to estimate the efficacy of a vancomycin-dosing protocol in reaching appropriate serum concentration in patients with and without kidney dysfunction.

METHODS

This was a retrospective study in critically ill patients treated with continuous infusion of vancomycin. Patients with creatinine clearance > 50 ml/min (Group A) were compared to those with creatinine clearance ≤ 50 ml/min (Group B).

RESULTS

348 patients were enrolled (210 in Group A, 138 in Group B). At first determination, patients with kidney dysfunction (Group B) had a statistically higher percentage of vancomycin in target range, while the percentage of patients with a VSC under the range was almost equal. These percentages differed at the subsequent measurements. The number of patients with low vancomycin concentration progressively decreased, except in those with augmented renal clearance; the percentage of patients with VSC over 30 mg/L was about 28 %, irrespective of the presence or absence of kidney dysfunction. Patients who reached a subtherapeutic level at the first VSC measurement had a significant correlation with in-hospital mortality.

CONCLUSIONS

Our protocol seems to allow a rapid achievement of a target VSC particularly in patients with kidney dysfunction. In order to avoid subtherapeutical VSC, our algorithm should be implemented by the estimation of the presence of an augmented renal clearance.

Antimicrobial Pharmacokinetics and Pharmacodynamics

BACKGROUND

Antimicrobial medications are beneficial when used appropriately, but adverse effects and resistance sometimes limit therapy. These effects may be more problematic with inappropriate antimicrobial use. Consideration of the pharmacokinetic and pharmacodynamic properties of these medications can help optimize drug use.

METHODS

Review of the pertinent English-language literature.

RESULTS

The pharmacokinetic principles of absorption, distribution, metabolism, and elimination determine whether an appropriate dose of medication reaches the intended pathogen. The pharmacodynamic properties of antimicrobial medications define the relation between the drug concentration and its observed effect on the target pathogen. Improvements in clinical outcomes have been observed when antimicrobial agents are dosed optimally according to these properties. In surgical patients, substantial changes in the volume of distribution and elimination necessitate a clear understanding of these principles. Additionally, less adverse drug effects and antimicrobial resistance may occur with optimal use of these drugs.

CONCLUSION

Selecting and dosing antimicrobial medications with consideration of pharmacokinetics and pharmacodynamics may improve patient outcomes and avoid adverse effects.

Renal replacement therapy in acute kidney injury: controversy and consensus

Renal replacement therapies (RRTs) represent a cornerstone in the management of severe acute kidney injury. This area of intensive care and nephrology has undergone significant improvement and evolution in recent years. Continuous RRTs have been a major focus of new technological and treatment strategies. RRT is being used increasingly in the intensive care unit, not only for renal indications but also for other organ-supportive strategies. Several aspects related to RRT are now well established, but others remain controversial. In this review, we review the available RRT modalities, covering technical and clinical aspects. We discuss several controversial issues, provide some practical recommendations, and where possible suggest a research agenda for the future.

The effect of pathophysiology on pharmacokinetics in the critically ill patient--concepts appraised by the example of antimicrobial agents

Critically ill patients are at high risk for development of life-threatening infection leading to sepsis and multiple organ failure. Adequate antimicrobial therapy is pivotal for optimizing the chances of survival. However, efficient dosing is problematic because pathophysiological changes associated with critical illness impact on pharmacokinetics of mainly hydrophilic antimicrobials. Concentrations of hydrophilic antimicrobials may be increased because of decreased renal clearance due to acute kidney injury. Alternatively, antimicrobial concentrations may be decreased because of increased volume of distribution and augmented renal clearance provoked by systemic inflammatory response syndrome, capillary leak, decreased protein binding and administration of intravenous fluids and inotropes. Often multiple conditions that may influence pharmacokinetics are present at the same time thereby excessively complicating the prediction of adequate concentrations. In general, conditions leading to underdosing are predominant. Yet, since prediction of serum concentrations remains difficult, therapeutic drug monitoring for individual fine-tuning of antimicrobial therapy seems the way forward.

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

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

Antibiotic dosing in critically ill patients with septic shock and on continuous renal replacement therapy: can we resolve this problem with pharmacokinetic studies and dosing guidelines?

Dosing antibiotics in critically ill patients to achieve therapeutic concentrations is a significant challenge. The presence of septic shock and prescription of continuous renal replacement therapy introduces further complexities for the clinician. Unfortunately, this is a dilemma encountered daily by intensivists. Although small pharmacokinetic studies are emerging to provide data to help address this problem, the variability in results from these studies is profound. As such, effective antibiotic dosing guidelines for critically ill patients who have septic shock and who receive continuous renal replacement therapy are not available. Dosing flowcharts and therapeutic drug monitoring represent the best available options for clinicians to optimize antibiotic dosing.