Antibiotic Dosing in Critically Ill Adult Patients Receiving Continuous Renal Replacement Therapy

Clinical Pharmacokinetics, Pharmacodynamics and Toxicodynamics of Polymyxins: Implications for Therapeutic Use

The availability of sensitive, accurate and specific analytical methods for the measurement of polymyxins in biological fluids has enabled an understanding of the pharmacokinetics of these important antibiotics in healthy humans and patients. Colistin is administered as its inactive prodrug colistin methanesulfonate (CMS) and has especially complex pharmacokinetics. CMS undergoes conversion in vivo to the active entity colistin, but the rate of conversion varies from brand to brand and possibly from batch to batch. The extent of conversion is generally quite low and depends on the relative magnitudes of the conversion clearance and other clearance pathways for CMS of which renal excretion is a major component. Formed colistin in the systemic circulation undergoes very extensive tubular reabsorption; the same mechanism operates for polymyxin B which is administered in its active form. The extensive renal tubular reabsorption undoubtedly contributes to the propensity for the polymyxins to cause nephrotoxicity. While there are some aspects of pharmacokinetic behaviour that are similar between the two clinically used polymyxins, there are also substantial differences. In this chapter, the pharmacokinetics of colistin, administered as CMS, and polymyxin B are reviewed, and the therapeutic implications are discussed.

Invasive Candidiasis in the Elderly: Considerations for Drug Therapy

Candida infections in the elderly are an important and expanding clinical problem, with significantly higher mortality in this group than in younger patients. The increasing problem of invasive Candida infections may be related to higher prevalence of immunocompromised older people and the emergence of treatment resistance. Older people, especially the frail and critically ill, are at higher risk of medication-related harmful effects due to changes in pharmacokinetics and pharmacodynamics, which may be further complicated by organ dysfunction, diminished homeostatic control, co-morbidities and polypharmacy. Here, we review the available options for the treatment of Candida infections and provide insights into the challenges surrounding the optimal use of antifungal drugs in the elderly.

Metronidazole- and levofloxacin-induced psychotic disorders in chronic kidney patient

We present a case which reports the occurrence of psychotic disorders after metronidazole and levofloxacin therapy in a chronic kidney patient while being treated for enterocolitis and urinary infection. A 48-year-old female was admitted to a hospital for the placement of a peritoneal dialysis catheter due to indicated peritoneal dialysis. During admission, symptoms of enterocolitis and urinary infection had occurred, so metronidazole and levofloxacin were introduced into therapy, respectively. After 4 days of metronidazole and 3 days of levofloxacin therapy, the patient became confused, disoriented, with signs of delirium. Since the diagnosis of psychoorganic disorder was made, the therapy with lorazepam and haloperidol was initiated, while metronidazole and levofloxacin were discontinued. Complete recovery 4 days after discontinuation indicates that the patient has experienced antibiotics-induced neurotoxicity. This is the first report of expressed neurotoxicity after the combination of metronidazole and levofloxacin in chronic kidney patients.

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.

Pharmacokinetic evaluation of meropenem and vaborbactam for the treatment of urinary tract infection

INTRODUCTION

Meropenem/vaborbactam (M/V) represents the first carbapenem and β-lactamase inhibitor combination approved for treatment of complicated urinary tract infections (cUTIs), including pyelonephritis. Vaborbactam is a novel boronic acid, β-lactamase inhibitor with a high affinity for serine β-lactamases, including Klebsiella pneumoniae carbapenemase (KPC). This combination, Vabomere™, was approved in August 2017 by the United States Food and Drug Administration for the treatment of cUTIs in patients 18 years or older, including pyelonephritis, caused by the following susceptible microorganisms: Escherichia coli, K. pneumoniae, and Enterobacter cloacae species complex. Areas covered: Relevant literature regarding microbiology, pharmacokinetics, pharmacodynamics, and clinical trials evaluating efficacy, safety, and tolerability will be discussed. Expert opinion: Current treatment options for KPC-producing infections such as aminoglycosides, polymyxins, fosfomycin, and tigecycline are associated with concerns regarding efficacy, toxicities, optimal dosing, and/or development of resistance. Additionally, resistance to the new combination product of ceftazidime/avibactam has also emerged. Current clinical evidence supporting the use of M/V for KPC-producing infections is limited to an open-label, randomized, phase III study in a small number of patients with serious infections due to carbapenem-resistant Enterobacteriaceae. Although M/V is not approved for KPC-producing infections, we believe that M/V will become a preferred agent for KPC-producing Enterobacteriaceae infections.

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

Background

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

Methods

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

Results

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

Conclusion

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

Prospective evaluation of a continuous infusion vancomycin dosing nomogram in critically ill patients undergoing continuous venovenous haemofiltration

Objectives

The most optimal method of attaining therapeutic vancomycin concentrations during continuous venovenous haemofiltration (CVVH) remains unclear. Studies have shown continuous infusion vancomycin (CIV) achieves target concentrations more rapidly and consistently when compared with intermittent infusion. Positive correlations between CVVH intensity and vancomycin clearance (CLvanc) have been noted. This study is the first to evaluate a CIV regimen in patients undergoing CVVH that incorporates weight-based CVVH intensity (mL/kg/h) into the dosing nomogram.

Methods

This was a prospective, observational study of patients undergoing CVVH and receiving CIV based on the nomogram. The primary outcome was achievement of a therapeutic vancomycin concentration (15-25 mg/L) at 24 h. Secondary outcomes included the achievement of therapeutic concentrations at 48 and 72 h.

Results

The nomogram was analysed in 52 critically ill adults. Vancomycin concentrations were therapeutic in 43/52 patients (82.7%) at 24 h. Of the nine patients who were not therapeutic at 24 h, seven were supratherapeutic and two were subtherapeutic. The mean (SD) concentration was 20.1 (4.2)  mg/L at 24 h, 20.7 (3.7) mg/L at 48 h and 21.9 (3.5)  mg/L at 72 h. Patients with CVVH intensity >20 mL/kg/h experienced higher CLvanc at 24 h compared with patients with CVVH intensity <20 mL/kg/h (3.1 versus 2.6 L/h; P = 0.013).

Conclusions

By incorporating CVVH intensity into the CIV dosing nomogram, the majority of patients achieved therapeutic concentrations at 24 h and maintained them within range at 48 and 72 h. Additional studies are required to validate this nomogram before widespread implementation may be considered.

Factors affecting serum concentration of vancomycin in critically ill oliguric pediatric patients receiving continuous venovenous hemodiafiltration

Vancomycin is known to be unintentionally eliminated by continuous renal replacement therapy, and the protein bound fraction of vancomycin is also known to be different in adults and children. However, there are only a few studies investigating the relationship between the dose of continuous venovenous hemodiafiltration (CVVHDF) parameters and serum concentration of vancomycin in pediatric patients. The aim of this study was to determine clinical and demographic parameters that significantly affect serum vancomycin concentrations. This retrospective cohort study was conducted at a pediatric intensive care unit in a tertiary university children’s hospital. Data from oliguric patients who underwent CVVHDF and vancomycin therapeutic drug monitoring were collected. The correlation between factors affecting serum concentration of vancomycin was analyzed using mixed effect model. A total of 177 serum samples undergoing vancomycin therapeutic drug monitoring were analyzed. The median age of study participants was 2.23 (interquartile range, 0.3–11.84) years, and 126 (71.19%) were male patients. Serum concentration of vancomycin decreased significantly as the effluent flow rate (EFR; P < 0.001), dialysate flow rate (DFR; P = 0.009), replacement fluid flow rate (RFFR; P = 0.008), the proportion of RFFR in the sum of DFR and RFFR (P = 0.025), and residual urine output increased. The adjusted R² of the multivariate regression model was 0.874 (P < 0.001) and the equation was as follows: Vancomycin trough level (mg/L) = (0.283 × daily dose of vancomycin [mg/kg/d]) + (365.139 / EFR [mL/h/kg])–(15.842 × residual urine output [mL/h/kg]). This study demonstrated that the serum concentration of vancomycin was associated with EFR, DFR, RFFR, the proportion of RFFR, and residual urine output in oliguric pediatric patients receiving CVVHDF.

Review of antimicrobial use and considerations in the elderly population

Pharmacologic management of infections in elderly patients presents multiple challenges to health care professionals due to variable pharmacokinetics, pharmacodynamics, and immune function. Age is a well-established risk factor for infection, but furthermore is a risk factor for prolonged length of hospital stay, increased incidence of complications, and significant and sustained decline in baseline functional status. In 2014, 46.2 million Americans were aged ≥65 years, accounting for 14.5% of the total population. By 2033, for the first time, the population of persons aged ≥65 years is projected to outnumber the people <18 years of age. According to the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey, 154 million prescriptions for antimicrobials were estimated to have been written in doctors’ offices and emergency departments during a 1-year time period. In 2014, 266.1 million courses of antimicrobials were dispensed to outpatients by US community pharmacies. A study that evaluated 2007–2009 Medicare Part D data found that patients aged ≥65 years used more antimicrobials, at 1.10 per person per year, compared to 0.88 antimicrobials used per person per year in patients aged 0–64 years. With the abundance of antimicrobial prescriptions and the current growth in the number and proportion of older adults in the US, it is essential that health care providers understand appropriate antimicrobial pharmacotherapy in the elderly patient. This review focuses on the use and implications of antimicrobial agents in the elderly population.

Pharmacokinetic and Pharmacodynamic Considerations of Antibiotics of Last Resort in Treating Gram-Negative Infections in Adult Critically Ill Patients

PURPOSE OF REVIEW

We provide an overview of antimicrobials that are considered last resort for the treatment of resistant gram-negative infections in adult critically ill patients. The role in therapy, pharmacodynamic (PD) goals, and pharmacokinetic (PK) changes in critical illness for aminoglycosides, polymyxins, tigecycline, fosfomycin, and fluoroquinolones are summarized.

RECENT FINDINGS

Altered PK in septic patients in the intensive care unit (ICU) is observed with many of our agents of last resort. Based on the available literature, dosage adjustments may be required to optimize PK parameters and meet PD targets for most effective bacterial killing. Data is limited, studies are conducted in heterogeneous patient populations, and conclusions are frequently conflicting. Strategic dosing regimens such as high-dose extended interval dosing of aminoglycosides or loading doses with colistin and polymyxin B are examples of ways to optimize antibiotic PK in critically ill patients. Benefits of these strategies must be balanced with risks of increased toxicity. Patients with resistant gram-negative infections may present with septic shock in the ICU. Sepsis can significantly alter the PK of antibiotics and require dosage adjustments to attain optimal drug levels. An understanding of PK and PD properties of these agents of last resort will help to maximize therapeutic efficacy while minimizing toxic effects.

Implication of Haemodiafiltration Flow Rate on Amikacin Pharmacokinetic Parameters in Critically Ill Patients

BACKGROUND

To analyse the effect of haemodiafiltration (CVVHDF) flow rate on amikacin pharmacokinetics and blood concentrations.

METHODS

Prospective observational study. Patients receiving CVVHDF and amikacin treatment were included. Pharmacokinetic parameters were calculated using Bayesian analysis. Spearman correlation test was used in order to assess the influence of CVVHDF flux on amikacin minimum concentration (Cmin) and plasma clearance.

RESULTS

Thirty patients undergoing CVVHDF procedures were included. The treatment with amikacin started at an initial mean dose of 12.4 (4.1) mg/kg/day. An association between the flow rate and Cmin value (r = 0.261; p = 0.161) and plasma clearance was found (r = 0.268; p = 0.152). Four patients (13.3%) were not able to achieve peak concentration over MIC value higher than 8. In 4 patients, amikacin had to be discontinued due to a high Cmin value.

CONCLUSIONS

Amikacin clearance in patients with CVVHDF is affected by the flow rate used. Therefore, CVVHDF dose should be taken into account when dosing amikacin.

Population Pharmacokinetics of Cefuroxime in Critically Ill Patients Receiving Continuous Venovenous Hemofiltration With Regional Citrate Anticoagulation and a Phosphate-Containing Replacement Fluid

BACKGROUND

Cefuroxime is frequently prescribed as an antimicrobial therapy in critically ill patients. The aim of this study was to develop a new intravenous dosing strategy for cefuroxime in critically ill patients undergoing continuous venovenous hemofiltration with regional citrate anticoagulation (RCA-CVVH) by analyzing its extracorporeal removal and pharmacokinetic (PK) parameters.

METHODS

Nine critically ill patients treated with intravenous cefuroxime and RCA-CVVH and a phosphate-containing replacement fluid were investigated. Arterial and effluent samples were obtained from all patients and pre- and postfilter venous blood samples were obtained from a subgroup of 5 patients. Plasma cefuroxime levels were determined by ultraperformance liquid chromatography-mass spectrometry in plasma samples collected before and after intravenous infusion of either 1500 mg cefuroxime every 12 hours or 3000 mg continuously over 24 hours. Population PK analysis and dosing simulations were performed using nonlinear mixed-effects modeling and Monte Carlo simulations.

RESULTS

The volume of distribution (VD) of cefuroxime in the central compartment, corrected for lean body mass, was 0.11 ± 0.056 L/kgLBMc, CVVH-mediated clearance was 49.5-50.6 mL/min, the mean elimination half-life (t½) was 90 minutes (77-103), and the mean sieving coefficient was 0.89 ± 0.01. A 2-compartment model with between-subject variability in clearance, VD, and t½ described these data adequately. Simulation of a standard dosing regimen (750 mg/12 hours) predicted failure to achieve the international target plasma cefuroxime concentration (32 mg/L).

CONCLUSIONS

Cefuroxime clearance by RCA-CVVH was twice the reported clearance during standard CVVH. Our PK data predicted that a maintenance dose of 3000 mg cefuroxime, infused over 24 hours, would provide an optimal steady-state plasma concentration of 38.5 mg/L. The developed population PK model for cefuroxime has the potential to inform new dosing schedules in patients receiving cefuroxime during RCA-CVVH.

Delayed introduction of immunosuppressive regimens in critically ill patients after liver transplantation

BACKGROUND

The manipulation of immunosuppression therapy remains challenging in patients who develop infectious diseases or multiple organ dysfunction after liver transplantation. We evaluated the outcomes of delayed introduction of immunosuppression in the patients after liver transplantation under immune monitoring with ImmuKnow assay.

METHODS

From March 2009 to February 2014, 225 consecutive liver recipients in our institute were included. The delayed administration of immunosuppressive regimens was attempted in 11 liver recipients with multiple severe comorbidities.

RESULTS

The median duration of non-immunosuppression was 12 days (range 5-58). Due to the infectious complications, the serial ImmuKnow assay showed a significantly low ATP level of 64±35 ng/mL in the early period after transplantation. With the development of comorbidities, the ImmuKnow value significantly increased. However, the acute allograft rejection developed when a continuous distinct elevation of both ATP and glutamyltranspeptidase levels was detected. The average ATP level measured just before the development of acute rejection was 271±115 ng/mL.

CONCLUSIONS

The delayed introduction of immunosuppressive regimens is safe and effective in management of critically ill patients after liver transplantation. The serial ImmuKnow assay could provide a reliable depiction of the dynamics of functional immunity throughout the clinical course of a given patient.

Pharmacokinetic/pharmacodynamic parameters for treatment optimization of infection due to antibiotic resistant bacteria: a summary for practical purposes in children and adults

In the last years, there has been a tremendous increase in the incidence of bacterial infections due to resistant strains, especially multi-drug resistant Gram-negative bacilli. In Europe, a north to south and a west to east gradient was noticed, with more than one third of the K. pneumonia isolates being resistant to carbapenems in few countries. New antibiotics are lacking and, as a consequence, pharmacokinetic/pharmacodynamic parameters, normalized to pathogen minimal inhibitory concentration, are used with increased frequency to treat infections due to difficult-to-treat pathogens. These parameters are available at least for the adult population, but sparse in many different publications. This review wants to provide a comprehensive and 'easy to read' text for everyday practice, briefly summarizing the presently available knowledge on pharmacokinetic/pharmacodynamic parameters (normalized for minimal inhibitory concentration values) of different class drugs, that can be applied for an effective antibacterial treatment infections due to antibiotic-resistant pathogens.

Considerations for Medication Management and Anticoagulation During Continuous Renal Replacement Therapy

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

Pharmacokinetics of linezolid during continuous hemodiafiltration: A case report

The pharmacokinetics of linezolid clearance (CL_LZD) during continuous hemodiafiltration (CHDF) has not been comprehensively analyzed. Here, we examined CL_LZD by CHDF in a patient with septic shock and disseminated intravascular coagulation due to methicillin-resistant Staphylococcus aureus. The extraction ratio of LZD by CHDF was 22.6%, and the protein-binding rate was 17.9% ± 7.7%. In addition, it was determined that the calculated total body clearance of LZD was 30.2 mL/min, plasma elimination half-life was 8.66 h, and the CL_LZD by the dialyzer used for CHDF was 23.0 mL/min. From the obtained pharmacokinetics, the CL_LZD of patients continuing CHDF was estimated to be approximately half of the reported CL_LZD for healthy subjects. In addition, the LZD concentration of the sepsis patient who underwent CHDF remained higher than the minimum inhibitory concentration and was similar to the LZD concentrations reported in normal renal function patients. Although further studies are warranted, when LZD is administered to patients treated with CHDF, the present findings suggest that dose regulation is not required.

Impact of β-lactam antibiotic therapeutic drug monitoring on dose adjustments in critically ill patients undergoing continuous renal replacement therapy

The objective of this study was to describe the effect of therapeutic drug monitoring (TDM) and dose adjustments of β-lactam antibiotics administered to critically ill patients undergoing continuous renal replacement therapy (CRRT) in a 30-bed tertiary intensive care unit (ICU). β-Lactam TDM data in our tertiary referral ICU were retrospectively reviewed. Clinical, demographic and dosing data were collected for patients administered β-lactam antibiotics while undergoing CRRT. The target trough concentration range was 1-10× the minimum inhibitory concentration (MIC). A total of 111 TDM samples from 76 patients (46 male) with a mean ± standard deviation age of 56.6 ± 15.9 years and weight of 89.1 ± 25.8 kg were identified. The duration of antibiotic therapy was between 2 days and 42 days. TDM identified a need for dose modification of β-lactam antibiotics in 39 (35%) instances; in 27 (24%) samples, TDM values resulted in decreasing the prescribed dose of β-lactam antibiotic whereas an increase in the prescribed dose occurred in 12 (11%) cases. In patients treated for hospital-acquired pneumonia and primary or secondary bacteraemia, the dose was required to be decreased in 10/25 (40%) and 7/46 (15%) cases, respectively, to attain target concentrations. β-Lactam TDM is a useful tool for guiding drug dosing in complex patients such as those receiving CRRT. Although over one-third of patients manifested concentrations outside the therapeutic range, most of these CRRT patients had excessive β-lactam concentrations.

Phase I trial to investigate the effect of renal impairment on isavuconazole pharmacokinetics

Purpose

The purpose of the study is to evaluate the effect of renal impairment (RI) and end-stage renal disease (ESRD) on the pharmacokinetics (PK) of isavuconazole and the inactive cleavage product, BAL8728.

Methods

A single intravenous dose of the prodrug isavuconazonium sulfate (372 mg, equivalent to 200 mg isavuconazole and 75 mg of BAL8728 cleavage product) was administered to healthy controls (parts 1 and 2) and participants with mild, moderate, or severe RI (part 2) or ESRD (part 1); ESRD participants received two doses of 200 mg isavuconazole, 1 h post-dialysis (day 1) and prior to dialysis (day 15). Plasma PK parameters for isavuconazole included maximum concentration (C_max), area under the concentration–time curve (AUC) from time of dose to 72 h (AUC₇₂), AUC extrapolated to infinity (AUC_∞), AUC to last measurable concentration (AUC_last), half-life (t_½ h), volume of distribution (V_z), and total clearance (CL), for the healthy control group versus those with mild, moderate, or severe RI or ESRD.

Results

Isavuconazole C_max values were 4% higher in mild RI and 7, 14, and 21% lower in participants with moderate RI, severe RI, or ESRD versus the healthy control group, respectively. When hemodialysis occurred post-dose (day 15), participants with ESRD had a 30% increase in AUC₇₂ for isavuconazole in parallel with reduction of extracellular volume induced by dialysis. Exposure (AUC_∞ and AUC_last) was not significantly different for participants with mild, moderate, or severe RI versus healthy controls although there was considerable variability. The t_1/2 (day 1) was 125.5 ± 63.6 h (healthy control group), 204.5 ± 82.6 h (ESRD group) in part 1, and 140.5 ± 77.7 h (healthy control group), 117.0 ± 66.2 h (mild RI), 158.5 ± 56.4 h (moderate RI), and 145.8 ± 65.8 L/h (severe RI) in part 2. CL was 2.4 ± 0.8 L/h (healthy control group) and 2.9 ± 1.3 L/h (ESRD group) in part 1 and 2.4 ± 1.2 L/h (healthy control group), 2.5 ± 1.0 L/h (mild RI), 2.2 ± 0.8 L/h (moderate RI), and 2.4 ± 0.8 L/h (severe RI) in part 2. The V_z was 382.6 ± 150.6 L in the healthy control group and 735.6 ± 277.3 L in ESRD patients on day 1 in part 1 of the study. In part 2 of the study, V_z was 410.8 ± 89.7 L in the healthy control group, 341.6 ± 72.3 L in mild RI, 509.1 ± 262.2 L in moderate RI, and 439.4 L in severe RI.

Conclusions

Based on the findings of this study, dose adjustments of isavuconazole are unlikely to be required in individuals with RI or in those with ESRD who receive hemodialysis.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-017-2213-7) contains supplementary material, which is available to authorized users.

Individualised antimicrobial dosing in critically ill patients undergoing continuous renal replacement therapy: focus on total drug clearance

Background

Continuous renal replacement therapy (CRRT) is common practice in critical care patients with acute renal failure.

Objectives

To evaluate the adequacy of antimicrobial doses calculated based on the total drug clearance and dose recommended by different guides in critically ill patients undergoing CRRT.

Methods

Retrospective observational study. Patients admitted to a critical care unit during May 2014 to May 2016 and subjected to CRRT were included. The recommended dose was established as the product of the usual dose of the drug by total drug clearance.

Results

177 antimicrobial agents, used in 64 patients were analysed; 45 (25.4%) antimicrobials were given in an insufficient dose (<20%) according to the theoretical calculation. Following the recommendations in the revised guidelines, between 10% and 20% of antimicrobials were given in insufficient doses. A higher success rate of treatment in those patients not receiving a low drug dosage was seen (35.2% vs 24.0%).

Conclusions

There is a great disparity between the antimicrobial dose prescribed, recommended and calculated based on drug clearance in critically ill patients undergoing CRRT.

Clinical Outcomes of Extended Versus Intermittent Infusion of Piperacillin/Tazobactam in Critically Ill Patients: A Prospective Clinical Trial

STUDY OBJECTIVE

To determine whether critically ill patients receiving extended-infusion (EI) piperacillin/tazobactam would have improved clinical outcomes compared with patients receiving intermittent infusions.

DESIGN

Single-center, open-label, prospective study.

SETTING

Twenty-two-bed intensive care unit (ICU) in a regional hospital in Hong Kong.

PATIENTS

A total of 367 adults who had a diagnosis of either bacterial infection or neutropenic fever and had received treatment with piperacillin/tazobactam for at least 48 hours between December 1, 2013, and August 31, 2015.

INTERVENTION

Patients were assigned to receive piperacillin/tazobactam as either a 4-hour EI (182 patients [EI group]) or a 30-minute intermittent infusion (185 patients [non-extended infusion (NEI) group]).

MEASUREMENTS AND MAIN RESULTS

All patients were followed for at least 14 days after treatment assignment. The primary outcome was the 14-day mortality rate after initiation of piperacillin/tazobactam. Secondary outcomes included in-hospital mortality rate, time to defervescence, duration of mechanical ventilatory support, length of ICU stay, and duration of hospital stay. Both groups demonstrated similar 14-day mortality (11.5% in the EI group vs 15.7% in the NEI group, p=0.29). The mean time to defervescence was significantly reduced in the EI group (4 days in the EI group vs 6 days in the NEI group, p=0.01); no significant differences between groups were noted in the other secondary outcomes. An Acute Physiology and Chronic Health Evaluation II score of 29.5 or higher was found to strongly predict 14-day mortality (p=0.03) by Classification and Regression Tree analysis. In the post hoc analyses, a 14-day mortality benefit was demonstrated in patients in the EI group in whom infectious organisms were identified (mortality rate 9.3% in the EI group vs 22.4% in the NEI group, p=0.01) and in whom respiratory tract infection was diagnosed (mortality rate 8.9% in the EI group vs 18.7% in the NEI group, p=0.02).

CONCLUSION

Both the EI and NEI groups demonstrated similar 14-day mortality. Post hoc subgroup analysis revealed a mortality benefit in patients in the EI group who had infectious organisms identified or were diagnosed with respiratory tract infections.

Influence of Renal Replacement Modalities on Amikacin Population Pharmacokinetics in Critically Ill Patients on Continuous Renal Replacement Therapy

The objective of this study was to describe amikacin pharmacokinetics (PK) in critically ill patients receiving equal doses (30 ml/kg of body weight/h) of continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodiafiltration (CVVHDF). Patients receiving amikacin and undergoing CVVH or CVVHDF were eligible. Population pharmacokinetic analysis and Monte Carlo simulation were undertaken using the Pmetrics software package for R. Sixteen patients (9 undergoing CVVH, 11 undergoing CVVHDF) and 20 sampling intervals were analyzed. A two-compartment linear model best described the data. Patient weight was the only covariate that was associated with drug clearance. The mean ± standard deviation parameter estimates were 25.2 ± 17.3 liters for the central volume, 0.89 ± 1.17 h(-1) for the rate constant for the drug distribution from the central to the peripheral compartment, 2.38 ± 6.60 h(-1) for the rate constant for the drug distribution from the peripheral to the central compartment, 4.45 ± 2.35 liters/h for hemodiafiltration clearance, and 4.69 ± 2.42 liters/h for hemofiltration clearance. Dosing simulations for amikacin supported the use of high dosing regimens (≥25 mg/kg) and extended intervals (36 to 48 h) for most patients when considering PK/pharmacodynamic (PD) targets of a maximum concentration in plasma (Cmax)/MIC ratio of ≥8 and a minimal concentration of ≤2.5 mg/liter at the end of the dosing interval. The mean clearance of amikacin was 1.8 ± 1.3 liters/h by CVVHDF and 1.3 ± 1 liters/h by CVVH. On the basis of simulations, a strategy of an extended-interval high loading dose of amikacin (25 mg/kg every 48 h) associated with therapeutic drug monitoring (TDM) should be the preferred approach for aminoglycoside treatment in critically ill patients receiving continuous renal replacement therapy (CRRT). (This study is a substudy of a trial registered at ClinicalTrials.gov under number NCT01403220.).

Dosing nucleoside reverse transcriptase inhibitors in adults receiving continuous veno-venous hemofiltration

BACKGROUND AND OBJECTIVE

Characteristics of nucleoside reverse transcriptase inhibitors (NRTIs) make the drug class susceptible to elimination via continuous veno-venous hemofiltration (CVVH), potentially leading to suboptimal drug concentrations if given at the recommended anephric doses during CVVH. The objective of this study was to formulate NRTI dosing recommendations for adults receiving CVVH.

METHODS

A mathematical formula that estimates the amount of drug likely to be removed during CVVH at various flow rates was used to calculate the supplemental NRTI dose required during CVVH.

RESULTS

A proposed table of dosing recommendations for NRTIs during CVVH is presented.

CONCLUSION

Clinicians should utilize these recommendations in the context of each individual patient, taking into consideration patient-specific factors and severity of illness. Future pharmacokinetic research correlating plasma and intracellular concentrations of NRTIs during CVVH is warranted to elucidate appropriate dosing.

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

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

A review of the pharmacokinetics and pharmacodynamics of aztreonam

The monobactam aztreonam is currently being re-examined as a therapeutic agent in light of the global spread of carbapenem resistance in aerobic Gram-negative bacilli and aztreonam's stability to Ambler class B metallo-β-lactamases. Of particular interest are the pharmacokinetic and pharmacodynamic properties of aztreonam alone and in combination with β-lactamase inhibitors. The choice of inhibitor may vary depending on the spectrum of β-lactamases produced by Enterobacteriaceae. The monobactam ring is also being used to produce new developmental monobactams. Thus, a greater understanding of aztreonam pharmacokinetics and dynamics is of great relevance in drug development. This review summarizes the pharmacokinetic profile of aztreonam in man and its pharmacodynamics in human and pre-clinical studies when studied alone and with β-lactamase inhibitors.

Pilot Study of the Pharmacokinetics of Cefotaxime in Critically Ill Patients with Acute Kidney Injury Treated with Continuous Renal Replacement Therapy

The objective of this study was to describe the pharmacokinetics of cefotaxime (CTX) in critically ill patients with acute kidney injury (AKI) when treated with continuous renal replacement therapy (CRRT) in the intensive care unit (ICU). This single-center prospective observational pilot study was performed among ICU-patients with AKI receiving ≥48 h concomitant CRRT and CTX. CTX was administered intravenously 1,000 mg (bolus) every 6 h for 4 days. CRRT was performed as continuous venovenous hemofiltration (CVVH). Plasma concentrations of CTX and its active metabolite desacetylcefotaxime (DAC) were measured during CVVH treatment. CTX plasma levels and patient data were used to construct concentration-time curves. By using this data, the duration of plasma levels above 4 mg/liter (four times the MIC) was calculated and analyzed. Twenty-seven patients were included. The median CTX peak level was 55 mg/liter (range, 19 to 98 mg/liter), the median CTX trough level was 12 mg/liter (range, 0.8 to 37 mg/liter), and the median DAC plasma level was 15 mg/liter (range, 1.5 to 48 mg/liter). Five patients (19%) had CTX plasma levels below 4 mg/liter at certain time points during treatment. In at least 83% of the time any patient was treated with CTX, the CTX plasma level stayed above 4 mg/liter. A dosing regimen of 1,000 mg of CTX given four times daily is likely to achieve adequate plasma levels in patients with AKI treated with CVVH. Dose reduction might be a risk for suboptimal treatment.

PK/PD analysis of biapenem in patients undergoing continuous hemodiafiltration

BACKGROUND

Continuous hemodiafiltration (CHDF) is used as renal replacement therapy for critically ill patients with renal failure, and to treat hypercytokinemia. Since CHDF also clears therapeutic agents, drug pharmacokinetics (PK) should be dependent upon CHDF conditions. Although the antibiotic biapenem (BIPM) is used in patients undergoing CHDF, the optimal therapeutic regimen in such patients has not been fully clarified. In this study, we investigated the PK of BIPM in patients with various levels of renal function undergoing CHDF with polysulfone (PS) membrane, and used PK models to identify the optimal administration regimen.

METHODS

BIPM (300 mg) was administered by infusion in patients undergoing CHDF (n = 7). Blood and filtrate-dialysate were collected for compartment and non-compartment analysis.

RESULTS

The sieving coefficient of PS membrane was 1.00 ± 0.06 (mean ± S.D., n = 7), and CHDF clearance of BIPM was found to be the sum of the dialysate flow rate (QD) and filtrate flow rate (QF). Non-CHDF clearance showed inter-individual variability (4.82 ± 2.48 L/h), depending on residual renal function and non-renal clearance. Based on the average PK parameters obtained with a compartmental model, maximal kill end point (over 40 % T > MIC4 μg/mL) was achieved with regimens of 300 mg every 6 h, 300 mg every 8 h, and 600 mg every 12 h. Monte Carlo simulation indicated that 300 mg infusion for 1 h every 6 h was optimal, and the probability of target attainment at MIC2 μg/mL was 90.2 %.

CONCLUSIONS

Our results establish the optimal regimen of BIPM in patients with various levels of renal function undergoing CHDF with a PS membrane.

Pharmacokinetic considerations for drugs administered in the critically ill

Significant physiological changes are common among critically ill patients. This case-based review describes the consequences of these changes on the selection and dosing of medications.

Population pharmacokinetics and dosing simulations of cefepime in septic shock patients receiving continuous renal replacement therapy

The aim of this study was to describe the population pharmacokinetics of cefepime in septic shock patients requiring continuous renal replacement therapy and to determine whether current or alternative dosing regimens can achieve PK/PD targets. In this observational PK study, 62 samples from 13 patients were analysed using non-linear mixed-effects modelling. Different dosing regimens were evaluated using Monte Carlo simulations with ultrafiltration flow rates (UFRs) of 1000, 1500 and 2000 mL/h. The probability of target attainment was calculated against a conservative (60% T(>MIC)) and a higher PK/PD target (100% T(>MIC)) against an MIC of 8 mg/L, the clinical susceptibility breakpoint for Pseudomonas aeruginosa. A one-compartment model with between-subject variability (BSV) on clearance and volume of distribution (V(d)) described the data adequately. UFR was supported as a covariate on both parameters. Typical values for clearance and V(d) were 4.4L/h (BSV 37%) and 40.9L (BSV 20%), respectively. Dosing simulations showed failure to achieve both a conservative and a higher PK/PD target using a dose of 1g q12h for patients treated with a high UFR (≥1500 mL/h). The dose of 2g q8h or 1g q6h leads to optimal target attainment for high UFR. One gram q8h is optimal for low UFR (≤1000 mL/h). We found important variability in PK parameters. Dosing simulations show that a dose of 2g q8h or 1g q6h is needed to ensure rapid achievement of adequate levels if the UFR is ≥1500 mL/h and 1g q8h for low UFR (≤1000 mL/h).

Therapeutic Drug Monitoring in Neonatal HSV Infection on Continuous Renal Replacement Therapy

Optimal acyclovir dosing under continuous renal replacement therapy (CRRT) in neonates is unknown. We monitored serum acyclovir levels and herpes simplex virus 1 (HSV-1) DNA levels in a neonate with disseminated HSV-1 infection and renal failure undergoing CRRT. A full-term, 5-day-old female presented with a 2-day history of lethargy and fever. She developed fulminant hepatitis and was diagnosed with HSV-1 infection by real-time polymerase chain reaction. Acyclovir was initiated at 60 mg/kg/day, which was lowered to 20 mg/kg/day because of development of renal failure. She was placed on continuous hemodialysis. Acyclovir dosing was adjusted according to serum acyclovir levels, and HSV-1 viral load was sequentially monitored. Semiquantification of serum HSV-1 levels was performed by real-time polymerase chain reaction. Acyclovir levels were measured by using liquid chromatography-tandem mass spectrometry. Acyclovir was administered at 20 mg/kg intravenously over 1 hour; peak concentration was 18.9 μg/mL. The half-life of acyclovir was estimated to be 2 to 3 h. Viral load remained high during dosing every 24 hours, with a decline of 0.17 log copies/24 hours. Acyclovir dosing was changed to 20 mg/kg/dose every 8 hours, with an average viral load decline of 0.44 log copies/24 hours. Despite the guideline recommendation of 24-hour redosing, acyclovir was dialyzed at a rate that resulted in suboptimal treatment. Individual therapeutic drug monitoring for acyclovir and dosing adjustment may be required to optimize therapy for patients undergoing CRRT.

Vancomycin continuous infusion versus intermittent infusion during continuous venovenous hemofiltration: slow and steady may win the race

Background

Vancomycin during continuous venovenous hemofiltration (CVVH) is either administered by intermittent infusion (II) or continuous infusion (CI). In this patient population, the best method to rapidly achieve target serum concentrations of 15 mcg/ml to 25 mcg/ml remains to be elucidated. We hypothesized that CI would achieve a target serum level of 15 mcg/ml to 25 mcg/ml within 24 h of the initiation of therapy more consistently than II.

Methods

A retrospective cohort study of adult patients admitted to the intensive care unit (ICU) between 2011 and 2014 receiving intravenous vancomycin with 24-hour serum level while on CVVH was included. Patients were excluded from this review if they had residual renal function during CVVH, were concomitantly on extracorporeal membrane oxygenation, or if the first dose of vancomycin was received six or more hours prior to the initiation of CVVH. The primary outcome was the achievement of a therapeutic level of 15mcg/ml to 25 mcg/ml by 24 hours.

Results

Fifty-nine patients met the inclusion criteria and 14 received CI and 45 in II. Therapeutic 24-hour levels were achieved in 14/14 versus 2/45 in CI and II, respectively (p < 0.001). Mean 24-hour vancomycin levels were 20.35 ± 2.78 mcg/ml for CI compared to 9.7 ± 3.52 mcg/ml for II (p < 0.001). Mean loading dose was 26.65 ± 3.06 mg/kg for CI compared to 17.58 ± 5.72 mg/kg for II (p < 0.001). Daily maintenance doses were 15.66 ± 6.26 mg/kg for CI compared to 17.28 ± 4.96 mg/kg for II (p = 0.339). In the subgroup of 27 patients who received vancomycin-loading dose >20 mg/kg, mean 24-hour levels were 20.35 ± 2.78 mcg/ml for CI versus 11.8 ± 2.7 mcg/ml for II (p < 0.001). No significant differences were found between patients in the two groups with respect to CVVH rate and length of CVVH prior to vancomycin administration.

Conclusions

The results of our study suggest that critically ill patients on CVVH treated with CI achieved the target level faster than II and consistently keep the vancomycin level within target range.

Role of therapeutic drug monitoring in pulmonary infections: use and potential for expanded use of dried blood spot samples

Respiratory tract infections are among the most common infections in men. We reviewed literature to document their pharmacological treatments, and the extent to which therapeutic drug monitoring (TDM) is needed during treatment. We subsequently examined potential use of dried blood spots as sample procedure for TDM. TDM was found to be an important component of clinical care for many (but not all) pulmonary infections. For gentamicin, linezolid, voriconazole and posaconazole dried blood spot methods and their use in TDM were already evident in literature. For glycopeptides, β-lactam antibiotics and fluoroquinolones it was determined that development of a dried blood spot (DBS) method could be useful. This review identifies specific antibiotics for which development of DBS methods could support the optimization of treatment of pulmonary infections.

Antimicrobial dosing in critically ill patients with sepsis-induced acute kidney injury

Severe sepsis often leads to multiple organ dysfunction syndromes (MODS) with acute kidney injury (AKI). AKI affects approximately, 35% of Intensive Care Unit patients, and most of these are due to sepsis. Mortality rate of sepsis-induced AKI is high. Inappropriate use of antimicrobials may be responsible for higher therapeutic failure, mortality rates, costs and toxicity as well as the emergence of resistance. Antimicrobial treatment is particularly difficult due to altered pharmacokinetic profile, dynamic changes in patient's clinical status and, in many cases, need for renal replacement therapy. This article aims to describe the appropriate antimicrobial dosing and reviews the factors contributing to the difficulties in establishing precise guidelines for antimicrobial dosing in sepsis-induced AKI patients.

SEARCH STRATEGY

Text material was collected by systematic search in PubMed, Google (1978-2013) for original articles.

Population pharmacokinetic-pharmacodynamic target attainment analysis of sulbactam in patients with impaired renal function: dosing considerations for Acinetobacter baumannii infections

This study aimed to perform a pharmacokinetic (PK)-pharmacodynamic (PD) target attainment analysis of sulbactam against Acinetobacter baumannii in patients with impaired renal function. The PK data (188 plasma samples and 27 urine samples) were modeled simultaneously. The mean population parameters were CLr (l/h) = 0.0792 × CLcr (ml/min), CLnr (l/h) = 2.35, Vc (l) = 12.2, Q (l/h) = 4.68 and Vp (l) = 4.44, where CLr and CLnr are the renal and non-renal clearances, Vc and Vp are the distribution volumes of the central and peripheral compartments and Q is intercompartmental clearance. The creatinine clearance (CLcr) was the most significant covariate. The determined MIC of sulbactam against A. baumannii clinical isolates (n = 27) was 0.75-6.0 μg/ml with MIC50 and MIC90 of 1 and 4 μg/ml, respectively. For sulbactam regimens, a Monte Carlo simulation estimated the probabilities of attaining the bactericidal target (60% of the time above the MIC) and determined the PK-PD breakpoints (the highest MICs at which the probabilities were 90% or more). In a patient with a CLcr of 15 ml/min, a regimen of 1 g twice daily achieved a 90% or more probability against the A. baumannii isolate population; however, 2 g four times daily was needed for a 90% or more probability in a patient with a CLcr of 90 ml/min. The results of the PK-PD target attainment analysis are useful when choosing the sulbactam regimen based on the CLcr of the patient and the susceptibility of A. baumannii.

REGISTRATION NUMBER

UMIN000007356.

Improving antimicrobial dosing in critically ill patients receiving continuous venovenous hemofiltration and the effect of pharmacist dosing adjustment

BACKGROUND

Appropriate antimicrobial dosing for patients receiving continuous venovenous hemofiltration (CVVH) is complex. Pharmacist participation in antimicrobial dosing adjustment for patients receiving CVVH may be advantageous.

METHODS

A comparative study was performed in a China hospital intensive care unit (ICU).Patients receiving CVVH in the intervention group received antimicrobial dosing adjustment service by pharmacists from January 2012 to June 2012, whereas patients in the control group received routine medical care between July 2012 and December 2012. The primary outcomes including patients' length of ICU stay, mortality in ICU, ICU hospitalization costs, and the occurrence of adverse drug events (ADEs) were then compared.

RESULTS

87 and 93 patients were included in the control and intervention groups. During the intervention period, pharmacists made 256 antimicrobial dosing adjustment recommendations for 93 enrolled patients receiving CVVH, of which 224 (87.5%) recommendations were accepted by physicians. Changing in CVVH-related variables (175, 68.4%) were the most common risk factors for dosing errors, whereas β-lactams (131, 51.2%) were the most frequency of antimicrobials associated with dosing errors. Compared with the control group, pharmacist dosing adjustment resulted in £1637.7 cost savings per patient, and 2.36 times reduction of antimicrobial-related adverse drug events (ADEs) (11 vs 26, P=0.002), while length of ICU stay and mortality in ICU showed no significant difference (P>0.05).

CONCLUSIONS

The involvement of pharmacist to participate in the ICU team rounds for patients receiving CVVH is associated with cost savings and reduction of ADEs. Hospital may consider employing ICU pharmacists.

The challenges of multiple organ dysfunction syndrome and extra-corporeal circuits for drug delivery in critically ill patients

The multiple organ dysfunction syndrome (MODS) is characterized by more than one organ system failing, especially during critical illness. MODS is the leading cause of morbidity and mortality in current ICU practice; moreover, multiple organ dysfunction, especially liver and kidneys, may significantly affect the pharmacokinetics (PKs) of different drugs that are currently administered in critically ill patients. These PK alterations may either result in insufficient drug concentrations to achieve the desired effects or in blood and tissue accumulation, with the development of serious adverse events. The use of extra-corporeal circuits, such as extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT), may further contribute to PKs changes in this patients' population. In this review, we have described the main PK changes occurring in all these conditions and how drug concentrations may potentially be affected. The lack of prospective studies on large cohorts of patients makes impossible any specific recommendation on drug regimen adjustment in ICU patients. Nevertheless, the clinicians should be aware of these abnormalities in order to better understand some unexpected therapeutic issues occurring in such patients.

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

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

Optimizing antimicrobial therapy in critically ill patients

Critically ill patients with infection in the intensive care unit (ICU) would certainly benefit from timely bacterial identification and effective antimicrobial treatment. Diagnostic techniques have clearly improved in the last years and allow earlier identification of bacterial strains in some cases, but these techniques are still quite expensive and not readily available in all institutions. Moreover, the ever increasing rates of resistance to antimicrobials, especially in Gram-negative pathogens, are threatening the outcome for such patients because of the lack of effective medical treatment; ICU physicians are therefore resorting to combination therapies to overcome resistance, with the direct consequence of promoting further resistance. A more appropriate use of available antimicrobials in the ICU should be pursued, and adjustments in doses and dosing through pharmacokinetics and pharmacodynamics have recently shown promising results in improving outcomes and reducing antimicrobial resistance. The aim of multidisciplinary antimicrobial stewardship programs is to improve antimicrobial prescription, and in this review we analyze the available experiences of such programs carried out in ICUs, with emphasis on results, challenges, and pitfalls. Any effective intervention aimed at improving antibiotic usage in ICUs must be brought about at the present time; otherwise, we will face the challenge of intractable infections in critically ill patients in the near future.

Antibiotic Dosing in Patients With Acute Kidney Injury: "Enough But Not Too Much"

Increasing evidence suggests that antibiotic dosing in critically ill patients with acute kidney injury (AKI) often does not achieve pharmacodynamic goals, and the continued high mortality rate due to infectious causes appears to confirm these findings. Although there are compelling reasons why clinicians should use more aggressive antibiotic dosing, particularly in patients receiving aggressive renal replacement therapies, concerns for toxicity associated with higher doses are real. The presence of multisystem organ failure and polypharmacy predispose these patients to drug toxicity. This article examines the pharmacokinetic and pharmacodynamic consequences of critical illness, AKI, and renal replacement therapy and describes potential solutions to help clinicians give "enough but not too much" in these very complicated patients.

Antibiotic stewardship in the intensive care unit

The rapid emergence and dissemination of antimicrobial-resistant microorganisms in ICUs worldwide constitute a problem of crisis dimensions. The root causes of this problem are multifactorial, but the core issues are clear. The emergence of antibiotic resistance is highly correlated with selective pressure resulting from inappropriate use of these drugs. Appropriate antibiotic stewardship in ICUs includes not only rapid identification and optimal treatment of bacterial infections in these critically ill patients, based on pharmacokinetic-pharmacodynamic characteristics, but also improving our ability to avoid administering unnecessary broad-spectrum antibiotics, shortening the duration of their administration, and reducing the numbers of patients receiving undue antibiotic therapy. Either we will be able to implement such a policy or we and our patients will face an uncontrollable surge of very difficult-to-treat pathogens.