DALI: defining antibiotic levels in intensive care unit patients: are current β-lactam antibiotic doses sufficient for critically ill patients?

Plasma Trough Concentrations of Beta-Lactam Antibiotics in the Early Phase of Septic Shock

INTRODUCTION

Septic shock necessitates timely antibiotic therapy, often with broad-spectrum beta-lactam antibiotics (ß-LA). To our knowledge, no previous study has examined antibiotic concentrations repeatedly during the initial phase of treatment. This observational study aimed to assess early-phase plasma concentrations of ß-LA in patients with septic shock.

METHOD

Prospective observational study of patients with septic shock, according to the SEPSIS-3 criteria, who received cefotaxime, piperacillin/tazobactam, or meropenem in accordance with Swedish practice. Demographic and clinical data were recorded for each patient. Consecutive blood samples were obtained during the first 24 h of treatment, and total antibiotic concentrations were measured using liquid chromatography mass spectrometry. Target concentrations were defined as 100% of the time that free (unbound) antibiotic concentrations remained above the minimal inhibitory concentration (fT > MIC).

RESULTS

Twenty-two patients were included, 15 (68%) were male and the median age was 65.5 years (IQR 46.3-65.5). In-hospital mortality was 7/22 (32%). Antibiotic exposure exceeding 100% fT > MIC was achieved in 16 (73%) of the patients. Four patients did not receive the recommended additional dose between the first and second doses of antibiotics; two of them still achieved 100% fT > MIC, whereas the other two attained 66% and 33% fT > MIC, respectively. Among the patients who received the additional dose, four did not achieve 100% fT > MIC. No relationship between mortality and fT > MIC was observed. Significant associations with achieving 100% fT > MIC were observed for older age (p = 0.045) and illness severity (SAPS3, p = 0.025).

CONCLUSION

Our findings demonstrate considerable variability in antibiotic exposure during the initial 24 h of septic shock treatment, highlighting a critical gap in understanding the clinical relevance of sub-optimal serum antibiotic concentrations and their potential impact on patient outcomes.

EDITORIAL COMMENT

Therapeutic drug monitoring of antimicrobials is increasingly being used in research and clinical practice.

Development and Validation of a High-Performance Liquid Chromatography-Ultraviolet Spectrometry Method for Ampicillin and Its Application in Routine Therapeutic Drug Monitoring of Intensive Care Patients

BACKGROUND

Ampicillin/sulbactam, a combination of a β-lactam and β-lactamase inhibitor, is widely used in clinical settings. However, therapeutic drug monitoring (TDM) of ampicillin is not commonly performed, particularly in intensive care units (ICUs). The purpose of this study was to develop and validate a rapid and cost-effective high-performance liquid chromatography (HPLC)-ultraviolet spectrometry method to quantify ampicillin in human serum and evaluate its clinical application in ICU patients.

METHODS

Sample cleanup included a protein precipitation protocol, followed by chromatographic separation on a C18 reverse-phase HPLC column within 12.5 minutes using gradient elution of the mobile phase. The assay was validated according to the German Society of Toxicology and Forensic Chemistry criteria. Clinical applications involved the retrospective analysis of TDM data from ICU patients receiving continuous infusion of ampicillin/sulbactam, including the attainment of target ranges and individual predicted and observed pharmacokinetics.

RESULTS

The method was robust, with linear relations between the peak area responses and drug concentrations in the range of 2-128 mg/L. The coefficient of variation for precision and the bias for accuracy (both interday and intraday) were less than 10%. Clinical application revealed variable pharmacokinetics of ampicillin in ICU patients (clearance of 0.5-31.2 L/h). TDM-guided dose adjustments achieved good therapeutic drug exposure, with 92.9% of the samples being within the optimal (16-32 mg/L) or quasioptimal (8-48 mg/L) range.

CONCLUSIONS

This method provides a practical solution for the routine TDM of ampicillin, facilitating individualized dosing strategies to ensure adequate therapeutic drug exposure. Given its simplicity, cost-effectiveness, and clinical relevance, HPLC-ultraviolet spectrometry holds promise for broad implementation in hospital pharmacies and clinical laboratories.

First dose target attainment with extended infusion regimens of piperacillin and meropenem

BACKGROUND

Standard dosing regimens of meropenem and piperacillin-tazobactam frequently fail to achieve targeted plasma concentrations in critically ill patients. Extended or continuous regimens are often used to improve target attainment. Although prompt antibiotic initiation is a major determinant of survival, few studies have reported systemic concentrations early after treatment initiation. No prior study has reported concentrations immediately after the loading dose and first extended infusion. This study aimed to evaluate plasma target attainment during the first dosing interval with an extended infusion regimen in a general intensive care unit (ICU).

METHODS

Adult ICU patients were prospectively included in conjunction with the first administration of meropenem or piperacillin-tazobactam. Treatment was initiated with a 0.5 h loading dose immediately followed by a 3 h extended infusion; typically 4 + 4 g piperacillin or 1(- 2)g + 1(- 2)g meropenem, in line with the local ICU protocol. Patients requiring renal replacement therapy were excluded. Plasma concentrations were measured post-loading dose (Cmax), near the end of the first extended infusion, and at the end of the first dosing interval (Cmin). Samples were analyzed using validated tandem mass spectrometry (UHPLC-MS/MS) methods. The primary endpoint was the proportion of patients achieving 100% time above minimum inhibitory concentrations (fT > MIC) during the first dosing interval. This was evaluated using observed Cmin above 2 mg/L (meropenem) and 20 mg/L (piperacillin). Additionally, published pharmacokinetic models were applied to the observed data for %fT > MIC estimation, using an a posteriori Bayesian approach.

RESULTS

We included 65 meropenem and 142 piperacillin measurements from 22 and 48 patients, respectively. Many patients (45% meropenem, 38% piperacillin) failed to reach 100% fT > MIC with the standard regimens used. Target non-attainment was associated with high estimated glomerular filtration rates (eGFR) and suspected augmented renal clearance (ARC). All meropenem patients that failed to reach target had eGFR > 90 mL/min/1.73 m2, as did 76% of corresponding piperacillin patients. Patients with suspected ARC frequently exhibited a tenfold or greater peak-to-trough decline (Cmin/Cmax < 0.1).

CONCLUSIONS

Despite aggressive dosing, plasma concentrations often fail to reach 100% fT > MIC during the first dosing interval. Alternative regimens and early plasma concentration measurements followed by adaptive dose adjustments should be considered to improve target attainment.

[Empirical antibiotic therapy in life-threatening infections-current concepts and controversies]

Along with early administration and the selection of the right drug, it is important to consider pharmacokinetic and pharmacodynamic principles, especially in life-threatening infections. Therefore, successful antibiotic therapy requires a clear understanding of the relationship between microbiology, pharmacology, and intensive care medicine. Open and transparent communication among professionals is essential for improving the quality of care. This article discusses current concepts and controversies by presenting a relevant case study of community-acquired pneumonia. It aims to help clinicians select the right drug for each patient, including the correct dose, the appropriate administration, and the right duration of treatment.

Predictive performance of population pharmacokinetic models in InsightRX® for model-informed precision dosing for Cefepime

BACKGROUND

Model-informed precision dosing (MIPD) is a promising tool used to ensure therapeutic antimicrobial concentrations. Model selection and sampling strategy might lead to different pharmacokinetic (PK) parameter estimates. Herein, we assess the predictive performance for cefepime PK in two models implemented within the InsightRX software using differing sampling approaches.

METHODS

Historic cefepime PK data and individual Bayesian estimates in predominantly critically ill patients, some of whom had extracorporeal support, served as the reference standard. Two population PK models (A; B) were evaluated using four sampling scenarios: (i) trough only, (ii) midpoint only, (iii) trough + midpoint, and (iv) peak + midpoint + trough. The median prediction error (MPE) and median absolute prediction error (MAPE) were calculated for clearance (CL) and volume of central compartment (Vc). Predicted categorical achievement of ≥70% time that the free drug concentration was greater than the minimum inhibitory concentration [fT>MIC(8/16mg/L)] was compared.

RESULTS

MAPE and MPE for CL and Vc resulted in variability that was dependent on model and sampling strategy. Both models' overall MPE and MAPE for CL were <±20 and <30% for all tested scenarios, respectively, with a low MPE of -2.4% to 4.4% on CL for sampling scenario 4. For Vc, MPE and MAPE were >±20 and >30% for the majority of test scenarios across both models, respectively. When excluding patients with extracorporeal support, MPE/MAPE for Vc decreased to 3.7-4.8/23.3%-34.5% and -7.9-2.5/25.2%-29.6% for model A and B, respectively. Using each model and sampling scheme, only four patients had discordant predicted achievement of ≥70% fT>MIC(8/16mg/L).

CONCLUSIONS

These two population PK models and all sampling scenarios demonstrated acceptable prediction of cefepime PK parameters and pharmacodynamic exposures; therefore, they demonstrated suitability for utilizing MIPD for cefepime therapeutic drug monitoring.

Inadequate imipenem dosing in patients with decreased kidney function: A clinical pharmacokinetic study

OBJECTIVES

A number of population pharmacokinetic (popPK) models of imipenem in critically ill patients are available for dosing optimisation, but they represent only a narrow range of kidney functions. This study evaluates the target attainment of on-label regimens through popPK modelling and simulation in patients across different kidney functions.

METHODS

A popPK model was built based on two datasets from Switzerland (model development population, 151 patients, 322 concentrations) and externally validated on two datasets from the Czech Republic (19 patients, 111 concentrations) and Vietnam (43 patients, 85 concentrations). Monte Carlo simulations were performed to evaluate the probability of target attainment (PTA) from a minimum inhibitory concentration (MIC) of 0.125 to 32 mg/L. We estimated the cumulative fraction of response (CFR) against Pseudomonas aeruginosa (the epidemiological cut-off value was 4 mg/L) across a broad range of Cockcroft-Gault creatinine clearance values (CLCRCG 15-130 mL/min). Targets of 40% and 100%ƒT>MIC (percentage of dosing interval estimated free concentrations above MIC) were investigated.

RESULTS

Decreased kidney function (eGFRCKD-EPI <90mL/min) was observed in 70/151 patients (46.4%) within the model development population, and in 11/19 (57.9%) and 24/43 (55.8%) patients in the Czech Republic and Vietnam, respectively. CLCRCG significantly influenced the imipenem clearance described by a two-compartment model. For PTA, all regimens achieved 40% ƒT>MIC2mg/L. With a 100%ƒT>MIC target, 500 mg q6h (CLCRCG 30-60 mL/min) could only cover a MIC of up to 1 mg/L, irrespective of infusion time. For CFR, no dosing regimen could cover susceptible P. aeruginosa for 100%ƒT>MIC.

CONCLUSIONS

The highest on-label imipenem dosing regimens failed to attain 100% ƒT>MIC4mg/L in patients with decreased kidney function. Higher dosing may be necessary to cover MIC of 4mg/L. Future trials should explore their efficacy, toxicity, and the utility of model-informed precision dosing in this population.

A Systematic Review of Antimicrobial Stewardship Interventions Implemented in Intensive Care Units

Antimicrobial stewardship (AS) is essential to ensure appropriate antimicrobial usage and subsequently reduce the emergence of microbial resistance. The intensive care unit is a crucial place for monitoring antimicrobial usage due the frequent exposure to infections. This review provides an update on the current status of antimicrobial stewardship intervention utilized in intensive care settings. A comprehensive search was performed in Cochrane, Web of Science, and PubMed using keywords grouped into Antimicrobial, Stewardship, and Intensive care unit. The search was restricted to original articles published from April 2015 to November 2024. Out of 1,234 records retrieved from the databases, 55 studies were included in this systematic review. Most of the studies were conducted in the United States (n = 9), followed by China (n = 8), India (n = 5), and Italy (n = 4). We identified seven key antimicrobial stewardship (AS) strategies: multi-interventions ASP (22 studies, 40%), prospective feedback and audit (11 studies, 20%), procalcitonin (PCT) protocols for guiding antimicrobial use (12 studies, 21.8%), protocols for antimicrobial de-escalation (4 studies, 7.3%), antimicrobial restrictions or preapprovals (4 studies, 7.3%), diagnostic stewardship (1 study, 1.8%), and guidelines for antimicrobial prescription (1 study, 1.8%). A reduction in targeted or overall antimicrobial usage was reported in most studies (34/42). Specifically, all studies implementing multi-invention ASPs reported a successful reduction in antimicrobial utilization. Some antimicrobial stewardship interventions significantly enhanced the appropriateness of antimicrobial prescriptions. In addition, patient health outcomes were not compromised by antimicrobial reduction. Nonetheless, future studies at a larger scale over a longer time are recommended to accurately assess the impact of AS programme on patient health outcomes.

Beta-Lactam Antibiotic Concentrations and the Acquisition of Multi-Drug Resistant Bacteria in Critically Ill Patients

Antimicrobial resistance (AMR) is a worldwide healthcare emergency. Whether insufficient beta-lactam antibiotic concentrations can be associated with AMR emergence remains controversial. This is a retrospective single-center cohort study including patients admitted to the intensive care unit of a tertiary university hospital from 2009 to 2014, who required a broad-spectrum beta-lactam antibiotic and had at least one therapeutic drug monitoring (TDM). Patients were categorized as having inadequate drug levels if the trough concentration (Cmin) fell below the clinical breakpoint for Pseudomonas aeruginosa. AMR was defined according to breakpoints recommended by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) using the disk diffusion method. A total of 444 patients (male sex, n = 313, 71%; female sex, n = 131, 29%; mean age 58 ± 15 years) were enrolled in the study. Patients received piperacillin/tazobactam (n = 168), ceftazidime/cefepime (n = 58) or meropenem (n = 218); among them, 65 (15%) had insufficient drug levels. Nine of these 65 (13.8%) patients with insufficient antibiotic levels acquired at least one pathogen with AMR within 15 days of TDM, when compared to 84/379 (22%) in the other group (OR 0.56 [95%CI 0.27-1.19]; p = 0.13). In a multivariable competing-risk analysis including male gender, APACHE score on admission, previous colonization by other MDR bacteria, urinary catheter, central venous catheter, mechanical ventilation, previous hospitalization and previous surgery, insufficient antibiotic levels were not associated with AMR acquisition (sHR 0.84 [95% CI 0.42-1.68]). Similar results were found when a higher threshold was used to define insufficient drug levels (Cmin < 4 times the clinical breakpoint). In conclusion, insufficient beta-lactam levels were not independently associated with AMR acquisition. Future prospective studies are needed to evaluate better the relationship between low drug levels and antibiotic resistance acquisition.

Impact of Hypothermic Temperature Control on Plasma and Soft Tissue Pharmacokinetics of Penicillin/Beta-Lactamase Inhibitor Combinations in Patients Resuscitated After Cardiac Arrest

BACKGROUND AND OBJECTIVES

Penicillin/beta-lactamase inhibitors are often used to treat aspiration pneumonia in patients resuscitated after cardiac arrest (CA). The impact of hypothermic temperature control on the pharmacokinetics of amoxicillin/clavulanate (AMO/CLAV) and ampicillin/sulbactam (AMP/SULB) has not been studied. Our objective was to evaluate the effects of hypothermic temperature control on the plasma and soft tissue pharmacokinetics of AMO/CLAV and AMP/SULB, including pulmonary concentrations of AMP/SULB, in patients resuscitated after CA.

METHODS

This prospective clinical study involved ten adult patients after CA receiving either AMO/CLAV 2 g/0.2 g or AMP/SULB 2 g/1 g intravenously every 8 h. Patients underwent hypothermic temperature control (33 ± 1 °C) for 24 h, followed by normothermia. Plasma, urine, muscle, and subcutaneous pharmacokinetics were measured and plasma protein-binding assessed for each subject. Microdialysis determined unbound drug concentrations in soft tissues. The pulmonary concentration of AMP/SULB was analyzed in the epithelial lining fluid.

RESULTS

No significant differences in plasma pharmacokinetics or renal excretion of AMO/CLAV and AMP/SULB were observed between the two temperature conditions. Soft tissue concentrations showed no consistent trend. Pharmacokinetic/pharmacodynamic targets (time that the unbound plasma concentrations were above the minimal inhibitory concentration [MIC] for MIC up to 8 mg/L) were met but not for 16 mg/L. Pulmonary concentrations of AMP/SULB in the epithelial lining fluid showed no clear trend.

CONCLUSION

This study indicates that hypothermic temperature control does not significantly affect plasma concentrations, soft tissue concentrations, or renal excretion of AMO/CLAV and AMP/SULB in patients resuscitated after CA. However, pulmonary concentrations of AMP/SULB exhibited interindividual variability.

Impact of Timing of Beta-Lactam Therapeutic Drug Monitoring and Therapy Adjustment in Critically Ill Patients

Purpose: To assess the impact of beta-lactam therapeutic drug monitoring (TDM) timing and therapy adjustment on clinical cure and 30-day mortality. Methods: This was a prospective study of critically ill patients admitted to the University of Florida Health Shands Hospital intensive care unit (ICU) between 2021 and 2022, ≥18 years old, and requiring beta-lactam therapy for a suspected or confirmed infection. Beta-lactam concentrations were measured per standard of care, pharmacokinetic/dynamic (PK/PD) target attainment was calculated, and therapy was adjusted if needed. Multiple regression and time-to-event (TTE) analyses were performed. Results: A total of 297 infection episodes from 268 patients were included. The mean (SD) age was 56 years (17), weight was 82 kg (32), and 14% received renal replacement therapy. The most common infection source was the lung, and the most common beta-lactam was cefepime. The most common infusion duration was 30 min. The median (IQR) time to first TDM was 2.7 days (1.7-4.7). Fifty-seven percent of patients required therapy adjustment. Increases in beta-lactam dose, frequency, or infusion duration were associated with lower 30-day mortality compared to continuing the same regimen (aOR 0.30, p = 0.015). Delay in performing TDM was associated with lower probability of clinical cure (aOR 0.92, p = 0.0023). Patients who had the regimen increased had shorter hospital stay compared to those who had it decreased. Timing of beta-lactam TDM in ICU patients was a significant predictor of clinical cure, while adjusting beta-lactam therapy to achieve higher exposure was a significant predictor of 30-day mortality.

Target attainment of benzylpenicillin in patients with infective endocarditis

OBJECTIVES

Benzylpenicillin is commonly used to treat infective endocarditis, particularly for streptococcal infections. This study aimed to perform pharmacokinetic/pharmacodynamic analyses of benzylpenicillin to assess the probability of target attainment (PTA) across different pathogens, MIC values, pharmacokinetic/pharmacodynamic targets, and renal function levels.

METHODS

In the Partial Oral Endocarditis Treatment trial, patients with left-sided infective endocarditis were randomly assigned to either conventional intravenous or partial oral antibiotic treatment. This substudy included patients receiving intravenous benzylpenicillin (3000 mg q6h). Pharmacokinetic measurements were conducted, and a population pharmacokinetic model was developed to estimate PTAs through model-based simulations. Pharmacokinetic/pharmacodynamic targets were based on time above MIC (or 4 × MIC) of the free concentration (fT > MIC or fT > 4 × MIC).

RESULTS

A total of 75 patients were included, and 291 plasma concentrations were obtained. MIC values were available for 68 patients. Individual target attainment for 50% fT > MIC and 50% fT > 4 × MIC targets was 100% (56/56) and 94.6% (53/56) for streptococci, 100% (3/3) for staphylococci, but only 66.7% (6/9) and 33.3% (3/9) for Enterococcus faecalis. For more stringent targets of 100% fT > MIC and 100% fT > 4 × MIC, individual target attainment was 89.3% (50/56) and 75.0% (42/56) for streptococci, 100.0% (3/3) and 66.7% (2/3) for staphylococci, but 33.3% (3/9) and 11.1% (1/9) for E. faecalis. Simulations showed PTAs above 90% for MIC values ≤ 0.5 mg/L at the 50% fT > MIC target, and for MIC values ≤ 0.063 mg/L at 50% fT > 4 × MIC or 100% fT > MIC targets. Higher renal clearance was associated with substantially lower PTAs.

DISCUSSION

Intravenous benzylpenicillin achieved target levels in most patients with infective endocarditis, particularly for those infected with streptococci or susceptible staphylococci. However, low individual target attainment in patients with E. faecalis suggests limitations in treating enterococcal endocarditis, especially in patients with preserved renal function.

Utilizing an Opportunistic Clinical Study and Population-Based Pharmacokinetic Models to Identify Rational Empiric Dosing Regimens for Piperacillin-Tazobactam in Critically Ill Patients

Determining an effective dosing regimen for piperacillin-tazobactam in critically ill patients is challenging due to substantial pharmacokinetic variability caused by complex pathophysiological changes. To address this need, a prospective clinical study was conducted, which enrolled 112 critically ill patients and employed an opportunistic sampling strategy. Population modeling and simulation were performed to characterize the pharmacokinetics (PK) and probability of target attainment (PTA) of piperacillin-tazobactam under various dosing regimens. Both piperacillin and tazobactam final models were one-compartment models with zero-order input and first-order elimination. Significant covariates included lean body weight for piperacillin and creatinine clearance along with continuous renal replacement therapy (CRRT) for both drugs. Monte Carlo simulations demonstrated that continuous infusion can achieve higher PTA than intermittent and extended infusions. When considering the minimum inhibitory concentration (MIC) of 16 mg/L for Pseudomonas aeruginosa (a frequently encountered bacterial pathogen among critically ill patients) and a PK/PD target of 100% fT >MIC, continuous infusion of 6 g/day is recommended for critically ill patients with a CLcr <60 mL/min, 9 g/day for patients with CLcr in the range of 60 to 129 mL/min, and 12 g/day for patients with a CLcr ≥130 mL/min. In addition, extended infusion represents a good alternative, especially the 3 g q6h or 4 g q6h regimens which can achieve the designated European Committee on Antimicrobial Susceptibility Testing (EUCAST) non-species-related PK/PD breakpoint of 8 mg/L. Our study provided valuable insight into PTA outcomes, which, together with individual renal function of future patients and institution-specific piperacillin susceptibility patterns, may assist physicians when making dosing decisions.

Whether to continue combining carbapenems to treat carbapenem-resistant Acinetobacter baumannii nosocomial pneumonia in critically ill patients: a retrospective efficacy and safety analysis

To explore the efficacy and safety of non-carbapenem-containing (NCC) regimens and carbapenem-containing regimens (CC) regimens, along with the factors influencing the outcomes in critically ill patients with carbapenem-resistant Acinetobacter baumannii (CRAB) pneumonia. This study retrospectively enrolled critically ill patients with CRAB pneumonia who were treated with NCC and CC regimens in a teaching hospital. The primary efficacy outcome was the 28-day clinical efficacy rate, and the safety outcome was the incidence of nephrotoxicity. After the propensity score matching analysis removed the differences between the two groups, the differences in outcomes were statistically analyzed. Cox regression and logistic regression models were used to analyze the factors influencing the outcomes of critically ill patients with CRAB pneumonia. Data from 168 critically ill patients with CRAB pneumonia were eventually included in this study for analysis (NCC = 84, CC = 84). The 28-day clinical efficacy rate was significantly lower in the CC group compared to the NCC group (40.5% vs. 57.1%, P = 0.031), and the incidence of nephrotoxicity was not significantly different in the two groups (P > 0.05). Logistic analysis showed that the prescription of carbapenems was the risk factor of decreased clinical efficacy (aOR = 0.494, 95%CI = 0.262-0.932, P = 0.029) and reduced microbiological eradication (aOR = 0.397, 95%CI = 0.201-0.783, P = 0.008) in patients. CC regimen may not contribute to the 28-day clinical efficacy of CRAB pneumonia and further studies are necessary to elucidate the CC regimen when treating CRAB pneumonia in critically ill patients.

Subtherapeutic Meropenem Antibiotic Exposure in Children With Septic Shock Assessed by Noncompartmental Pharmacokinetic Analysis in a Prospective Dataset

OBJECTIVES

To define meropenem plasma concentrations and pharmacodynamic exposure metrics in children with septic shock during the first 3 days of PICU hospitalization.

DESIGN

Pharmacokinetic sampling was undertaken in 19 subjects receiving standard meropenem dosing (20 mg/kg/dose, 8 hr) recruited from March 2019 to March 2022. Sampling occurred once each day following meropenem given 24 hours apart, during the first 3 PICU days. Data analysis was completed in 2023 and noncompartmental analysis was performed to assess pharmacodynamic exposure targets for sepsis. Clearance and volume of distribution at 20 mg/kg/dose were used to simulate mean exposures at 40 and 60 mg/kg/dose.

SETTING

PICU in a tertiary care center.

SUBJECTS

Patients 4 weeks old or older with hypotension requiring fluid resuscitation and vasopressor therapy, receiving meropenem as empiric therapy for sepsis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Augmented renal clearance (ARC) was documented in eight of 19 subjects, previously associated with subtherapeutic plasma concentrations, while three of 19 had acute kidney injury and decreased renal clearance. When assessed by pharmacodynamic exposure targets for sepsis (plasma meropenem concentrations above the minimum inhibitory concentration [MIC] of Pseudomonas aeruginosa for 70% or 100% of the dosing interval), ten of 19 and nine of 19 children, respectively, had subtherapeutic plasma meropenem exposures during PICU day 1, even for pathogens with an MIC considered "susceptible" by U.S. Food and Drug Administration criteria. Therapeutic meropenem pharmacodynamic exposures were associated with a positive 24-hour fluid balance on PICU day 1 and a negative 24-hour fluid balance by day 3, although profound variability was noted in fluid administered and renal output.

CONCLUSIONS

Given the variability in meropenem systemic exposure in pediatric septic shock, therapeutic drug monitoring, or monitoring for ARC, is suggested during the first days of hospitalization to allow daily assessments of dosing needs to achieve pharmacodynamic exposure targets for sepsis.

A real-world investigation into prescribing patterns and effectiveness of ceftolozane/tazobactam among critically ill patients from SPECTRA

BACKGROUND

Ceftolozane/tazobactam (C/T) real-world use was examined in a global population of critical care patients treated in intensive care unit settings.

METHODS

The Study of Prescribing patterns and Effectiveness of Ceftolozane/Tazobactam Real-world Analysis (SPECTRA) is a multinational, retrospective observational study of 617 adults treated with C/T conducted between 2016 and 2020. Population-associated clinical, treatment-related, and microbiologic characteristics, resource utilization, and clinical outcomes were assessed in critical care patients.

RESULTS

In this SPECTRA critical care cohort (n=298), 81.5% had ≥1 comorbidity. Common infection sites were respiratory (50.0%), skin/wound/tissue (21.1%), blood (13.7%), and urine (10.3%); common pathogens were Pseudomonas aeruginosa (89.7%; 66.7% multidrug resistant), Klebsiella spp. (6.9%), and Escherichia coli (6.4%); 51.7% received C/T as third-line/salvage therapy. Thirty-day readmission rates were 3.4% (all cause) and 1.7% (infection related). Overall clinical success was 53.4% (95% confidence interval: 47.5% to 59.1%) and was greater with first-line C/T (62.2%) versus third line (45.5%). All-cause in-hospital mortality was 35.6%; infection-related mortality was 13.8%.

CONCLUSIONS

In this multinational, high-risk cohort, most patients had beneficial outcomes despite their clinical complexity and late intervention with C/T. These results support C/T use against a wide range of Gram-negative pathogens in critical care settings.

TRIAL REGISTRATION

Not applicable due to retrospective design.

Standard versus double dosing of beta-lactam antibiotics in critically ill patients with sepsis: The BULLSEYE study protocol for a multicenter randomized controlled trial

BACKGROUND

Sepsis and septic shock are significant global healthcare challenges with high mortality rates. Effective management requires timely and adequate antimicrobial therapy. Beta-lactam antibiotics, commonly used in patients with sepsis, are crucial for treating these infections. However, standard dosing often leads to insufficient plasma levels due to dynamic physiological changes in critically ill patients. Previous randomized controlled trials highlighted the need for timely dose adjustments to improve clinical outcomes. This is the study protocol for the BULLSEYE trial in which we aim to optimize antibiotic treatment during the initial 48 h of sepsis by comparing standard to double dosing of beta-lactam antibiotics.

METHODS

This open-label, multicenter, randomized controlled trial will compare standard to double dosing of beta-lactam antibiotics (cefuroxime, ceftazidime, ceftriaxone, cefotaxime, amoxicillin, amoxicillin/clavulanic acid, flucloxacillin, meropenem, and piperacillin/clavulanic acid) in critically ill patients with septic shock. Participants will be randomized into two arms: the control arm receiving standard care, and the intervention arm receiving double antibiotic doses for 48 h, irrespective of renal function. Following this period, all patients will receive standard doses as per local protocol. The primary outcome is all cause 28-day mortality, with secondary outcomes including 90-day, 365-day, hospital and ICU mortality, hospital and ICU length of stay, SOFA scores, time to shock reversal, microbiological eradication, clinical cure, pharmacodynamic target attainment, safety, quality of life, and medical consumption.

DISCUSSION

The BULLSEYE trial aims to improve sepsis treatment in critically ill patients. Despite anticipated recruitment challenges, its large sample size ensures robust comparability. This pivotal trial could significantly impact sepsis treatment, leading to better clinical outcomes.

TRIAL REGISTRATION

EU_CT 2024-512950-13-00. Protocol version 2.3, protocol date 09-12-2024. Prospectively registered on 09-01-2025 at Clinicaltrails.gov nr. NCT06766461.

Pharmacokinetic variability and significance of therapeutic drug monitoring for broad-spectrum antimicrobials in critically ill patients

Critically ill patients are susceptible to serious infections due to their compromised conditions and extensive use of medical devices, often requiring empiric broad-spectrum antimicrobial therapy. Failure of antimicrobial therapy in this vulnerable population has a direct impact on the patient's survival; hence, selecting the optimal dosage is critical. This population, however, exhibits complex and diverse disease-related physiological changes that can markedly alter antimicrobial disposition. Inflammatory cytokines overexpressed in the systemic inflammatory response syndrome increase vascular permeability, leading to higher volume of distribution for hydrophilic antimicrobials. These cytokines also downregulate metabolic enzyme activities, reducing the clearance of their substrates. Hypoalbuminemia can increase the volume of distribution and clearance of highly protein-bound antimicrobials. Acute kidney injury decreases, while augmented renal clearance increases the clearance of antimicrobials primarily excreted by the kidneys. Furthermore, continuous renal replacement therapy and extracorporeal membrane oxygenation used in critical illness substantially affect antimicrobial pharmacokinetics. The complex interplay of multiple factors observed in critically ill patients poses a significant challenge in predicting the pharmacokinetics of antimicrobials. Therapeutic drug monitoring is the most effective tool to address this issue, and is proactively recommended for vancomycin, teicoplanin, aminoglycosides, voriconazole, β-lactams, and linezolid in critically ill patients. To streamline this process, model-informed precision dosing is expected to promote personalized medicine for this population.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2024

The 2024 revised edition of the Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock (J-SSCG 2024) is published by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine. This is the fourth revision since the first edition was published in 2012. The purpose of the guidelines is to assist healthcare providers in making appropriate decisions in the treatment of sepsis and septic shock, leading to improved patient outcomes. We aimed to create guidelines that are easy to understand and use for physicians who recognize sepsis and provide initial management, specialized physicians who take over the treatment, and multidisciplinary healthcare providers, including nurses, physical therapists, clinical engineers, and pharmacists. The J-SSCG 2024 covers the following nine areas: diagnosis of sepsis and source control, antimicrobial therapy, initial resuscitation, blood purification, disseminated intravascular coagulation, adjunctive therapy, post-intensive care syndrome, patient and family care, and pediatrics. In these areas, we extracted 78 important clinical issues. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) 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, 42 GRADE-based recommendations, 7 good practice statements, and 22 information-to-background questions were created as responses to clinical questions. We also described 12 future research questions.

Population pharmacokinetics of polymyxin B in critically ill patients with carbapenem-resistant organisms infections: insights from steady-state trough and peak plasma concentration

Aims

To establish a population pharmacokinetic (PopPK) model of polymyxin B (PMB) in critically ill patients based on steady-state trough (Ctrough,ss) and peak (Cpeak,ss) concentrations, optimize the dosing regimen, and evaluate the consistency of 24-hour steady-state area under the concentration-time curve (AUCss,24h) estimation between model-based and the two-point (Ctrough,ss and Cpeak,ss) methods.

Methods

PopPK modeling was performed using NONMEM, Monte Carlo simulations were used to optimize PMB dosing regimens. Bland-Altman analysis was used to evaluate the consistency between the two AUCss,24h estimation methods.

Results

A total of 95 patients, contributing 214 blood samples, were included and categorized into a modeling group (n = 80) and a validation group (n = 15). A one-compartment model was developed, with creatinine clearance (CrCL) and platelet count (PLT) identified as significant covariates influencing PK parameters. Simulation results indicated that when a Minimum Inhibitory Concentration (MIC) ≤ 0.5 mg·L-1, a probability of target attainment (PTA) ≥ 90% was achieved in all groups except for the 50 mg every 12 h (q12h) maintenance dose group. PTA decreased as CrCL increased, with slight variations observed across different PLT levels. The 75 mg and 100 mg q12h groups showed a higher proportion of AUCss,24h within the therapeutic window. Bland-Altman analysis revealed a mean bias of 12.98 mg·h·L-1 between the two AUCss,24h estimation methods. The Kappa test (κ = 0.51, P < 0.001) and McNemar's test (P = 0.33) demonstrated moderate agreement, reflecting overall consistency with minor discrepancies in classification outcomes.

Conclusion

The PopPK model of PMB is well-suited for critically ill patients. The 75 mg q12h and 100 mg q12h regimens are appropriate for critically ill patients, with CrCL levels guiding individualized dosing. A two-point sampling strategy can be used for routine therapeutic drug monitoring (TDM) of PMB.

Urinary Biomarkers and Attainment of Cefepime Therapeutic Targets in Critically Ill Children

BACKGROUND

Critically ill children are at risk for subtherapeutic antibiotic concentrations. The frequency of target attainment and risk factors for subtherapeutic concentrations of cefepime in children have not been extensively studied.

METHODS

We performed an observational study in critically ill children receiving a new prescription of standard dosing of cefepime for suspected sepsis (≥2 systemic inflammatory response syndrome criteria within 48 hours of cefepime start). Three plasma cefepime concentrations were measured at steady state and, a urine sample was collected prior to pharmacokinetics (PK) sampling for measurement of urinary biomarkers. Bayesian analysis determined cefepime PK for each individual, and simulations were used to estimate time above minimum inhibitory concentration (fT > MIC) for 8 µg/mL (breakpoint for Pseudomonas). Clinical factors and urinary biomarkers were compared between patients who did and did not achieve 100% fT > MIC. Correlations between covariates and cefepime PK parameters, as well as optimal cut points to identify <100% fT > MIC, were evaluated.

RESULTS

Twenty-one subjects were enrolled and PK sampling occurred after a median of 5 doses (range, 3-9); 43% of children achieved 100% fT > MIC for an MIC of 8 µg/mL. Younger age and lower urinary biomarkers (neutrophil gelatinase-associated lipocalin and kidney injury molecule-1) were significantly associated with failure to attain 100% fT > 8 µg/mL. Urinary neutrophil gelatinase-associated lipocalin (<122.1-ng/mg creatinine) best identified individuals who failed to attain this putative target (positive predictive value, 91.7%).

CONCLUSIONS

A large proportion of critically ill children failed to attain target concentrations for empiric treatment of Pseudomonas aeruginosa with cefepime. Urinary biomarkers may be a noninvasive means to identify those at higher risk for increased cefepime clearance and subtherapeutic concentrations.

Short, extended and continuous infusion of β-lactams: predicted impact on target attainment and risk for toxicity in an ICU patient cohort

OBJECTIVES

This study aimed to predict the impact of different infusion strategies on pharmacokinetic/pharmacodynamic (PK/PD) target attainment and the potential risk for toxicity in an ICU cohort treated with β-lactams.

METHOD

Using collected patient data from 137 adult ICU patients, and applying population PK models, individual PK parameters were estimated and used to predict concentrations and target attainment following cefotaxime 2 g q8h, piperacillin/tazobactam 4.5 g q6h and meropenem 1 g q8h, applying 15 min short infusions (SI), 3 h extended infusions (EI) and 24 h continuous infusion (CI). The MIC level of the most common primary pathogens, and the worst-case scenario (WCS) pathogen, were used in analyses.

RESULTS

For primary pathogens, target was reached in 94% (129/137) using SI. For WCS pathogens treated with piperacillin/tazobactam and meropenem, 78% (65/83) and 92% (76/83) reached target using SI and EI, respectively. However, target attainment was lower for cefotaxime [SI: 31% (17/54), EI: 44% (24/54)]. Overall, the number of individuals with potentially toxic concentrations was low, both in EI (n = 7) and SI (n = 5). For CI and WCS, target was reached in 50% (27/54), 96% (54/56) and 93% (25/27) for cefotaxime, piperacillin/tazobactam and meropenem, respectively.

CONCLUSIONS

In a Swedish ICU cohort target attainment rates for primary pathogens were high regardless of infusion strategy. In WCS pathogens, SI was insufficient, suggesting the benefit of routine use of EI or CI. However, for cefotaxime, target attainment remained low also with EI and CI. The use of CI might lead to unnecessarily high concentrations, but well-established toxicity levels are lacking and future studies are warranted.

Impact of prolonged versus intermittent infusion of meropenem on mortality and clinical outcomes in patients with severe infection: A systematic review and meta-analysis

OBJECTIVES

To compare the clinical outcomes of patients with severe infection treated with prolonged or intermittent infusion of meropenem.

METHODS

PubMed, Embase, and Cochrane Central databases were searched until July 2023. Randomized controlled trials (RCTs) or observational studies comparing prolonged versus intermittent infusion of meropenem were considered eligible. The primary outcomes included all-cause mortality and clinical improvement, while secondary outcomes encompassed hospital and intensive care unit (ICU) stay duration, microbial eradication rate, and adverse events. A meta-analysis was conducted using a random-effects model. The risk of bias of included studies was assessed using the modified JADAD scale for RCTs and the Newcastle-Ottawa Scale for observational studies.

RESULTS

Fourteen studies were included, with a total of 1698 patients. Prolonged infusion of meropenem was associated with a significantly lower mortality rate compared to intermittent infusion (RR = 0.81, 95 % CI: 0.68-0.98). It also significantly improved clinical improvement rates (RR = 1.35, 95 % CI: 1.11-1.64) and microbial eradication rates (RR = 1.19, 95 % CI: 1.08-1.32). There were no statistically significant differences in ICU length of stay or hospital length of stay. Subgroup analyses showed that prolonged infusion was significantly associated with lower mortality and better clinical improvement rates in patients with an APACHE II score <20.

CONCLUSIONS

Prolonged infusion of meropenem is more effective than intermittent infusion in reducing mortality, improving clinical outcomes, and enhancing microbial eradication, without increasing adverse events. These benefits are particularly evident in patients with lower disease severity (APACHE II < 20), emphasizing the importance of patient stratification in optimizing treatment strategies.

REGISTRATION

This systematic review and meta-analysis is registered with PROSPERO (number: CRD42023445360).

Therapeutic Drug Monitoring of High-dose Sulbactam in Pediatric Patients: Preliminary Data From a Prospective Observational Pharmacokinetic Study

BACKGROUND

Rates of carbapenem-resistant Acinetobacter baumannii are rising in Thailand. Although high-dose (HD) sulbactam is recommended for treating carbapenem-resistant A. baumannii infections, data on plasma sulbactam concentrations in children are limited. We aimed to evaluate plasma sulbactam concentrations and pharmacokinetic-pharmacodynamic (PK-PD) target achievement in pediatric patients.

METHODS

Prospective study data (January-November 2023) on children (1 month-18 years) who received sulbactam every 6-8 hours were analyzed. Mid-dosing ( Cmid , 50% f T) and trough ( Ctrough , 100% f T) concentrations were evaluated. PK-PD target achievement [50% f T > minimum inhibitory concentration (MIC), 100% f T > MIC] was evaluated using Clinical and Laboratory Standards Institute 2024 MIC cutoffs and MIC data of isolates of Acinetobacter calcoaceticus-baumannii complex from this study.

RESULTS

Thirty-five patients (median age 50 months) were categorized into standard-dose (SD) or HD groups. The geometric mean Cmid was higher in the HD (41.3 mg/L) versus SD (19.5 mg/L) groups ( P = 0.006). Among 101 isolates of Acinetobacter calcoaceticus-baumannii complex, the MIC50 and MIC90 (concentrations that inhibit 50% and 90% of isolates of the A. calcoaceticus-baumannii complex) were 16 and 128 mg/L, respectively. The HD group achieved Cmid >MIC50 in 87.5% of the patients compared with 63.6% in SD ( P = 0.17). Within the HD group, patients with augmented renal clearance (ARC) had lower Cmid (geometric mean 31.9 mg/L) compared with non-ARC (geometric mean 63.4 mg/L) ( P = 0.04).

CONCLUSIONS

HD sulbactam resulted in higher Cmid and PK-PD achievement. ARC significantly compromised plasma sulbactam concentration. HD sulbactam may be preferable for treating critically ill pediatric patients and those with ARC, especially during the empirical period.

Pharmacokinetic and Pharmacodynamic Approaches to Optimize Antibiotic Use in Neonates

Newborn infants (particularly those born preterm) are frequently exposed to empiric antibiotics at birth, and antibiotics are among the most commonly prescribed medications in neonatal intensive care units. Challenges in optimizing neonatal antibiotic dosing include: technical and ethical barriers to neonatal pharmacoanalytic study design and sampling, difficulty in extrapolating adult and pediatric data due to unique neonatal physiology, and a lack of validated pharmacodynamic targets specific to neonatal populations. In this review, we summarize basic concepts in pharmacokinetics (PK) and pharmacodynamics (PD), describe pharmacometric strategies utilized in contemporary PK/PD analyses, and review the evolution of PK/PD data guiding neonatal dosing among 3 commonly used antibiotics.

Cystatin C-Guided Dosing Nomogram Improves Target Attainment for Cefepime in the Critically Ill

OBJECTIVES

Estimated glomerular filtration rate is more accurate with combined creatinine and cystatin C equations (eGFRcr-cys) than creatinine alone. This study created and evaluated a cefepime dosing nomogram based on eGFRcr-cys for initial dosing in the critically ill.

DESIGN

Pharmacokinetic modeling and simulation study.

SETTING

Academic medical center.

PATIENTS

Critically ill adults treated with cefepime.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data from 120 patients with baseline cystatin C and follow-up cefepime levels were used to develop a nomogram based on eGFRcr-cys and weight for initial cefepime dosing. The predicted proportion of patients who achieved a free cefepime concentration above the minimum inhibitory concentration of the organism for 100% of the dosing interval in the first 24 hours (100% ƒT > MIC at 24 hr) was compared between administered doses and those predicted by the nomogram doses. Overall drug exposure was estimated with the free area under the concentration time curve from 0 to 24 hours (ƒAUC0-24) and compared between administered and nomogram doses. Achievement of 100% ƒT > MIC at 24 hours was predicted to be significantly better with the nomogram compared with the administered dose (76% vs. 38%; p < 0.001). The median ƒAUC0-24 as predicted by the nomogram (666 mg·hr/L) was slightly higher than the actual ƒAUC0-24 with administered doses (612 mg·hr/L; p = 0.01), but the nomogram led to fewer ƒAUC0-24 values which were either too high (> 900) or too low (< 300) (7% vs. 20%; p = 0.004).

CONCLUSIONS

Use of a cystatin C-inclusive dosing nomogram for cefepime could improve target attainment without increasing the risk of potentially toxic levels in the critically ill.

Navigating pharmacokinetic and pharmacodynamics challenges of β-lactam antibiotics in patients with low body weight: efficacy, toxicity, and dosage optimization

Background

Patients with low body weight (LBW) often exhibit altered pharmacokinetics (PK) in renal clearance and total body water. These changes complicate β-lactam antibiotic dosing, potentially resulting in suboptimal efficacy or increased toxicity.

Objectives

To evaluate the attainment of PK/pharmacodynamic (PD) targets, the prevalence of subtherapeutic and supratherapeutic concentrations, and the incidence of neurotoxicity among LBW patients treated with piperacillin/tazobactam (TZP), cefepime (FEP), and meropenem (MEM).

Design

A prospective observational study conducted at a tertiary hospital from January 2020 to December 2022.

Methods

Adult patients with a body mass index ⩽18.5 kg/m2 who received TZP, FEP, or MEM were included. Trough serum concentrations were analyzed for PK/PD targets: 100% time above minimum inhibitory concentration (100% fT > MIC) and 100% time above four times MIC (100% fT > 4MIC). Neurotoxicity was assessed using standardized criteria. Statistical analyses identified factors associated with concentration variability and adverse outcomes.

Results

Seventy-two patients were included: 29 received TZP, 23 FEP, and 20 MEM. Achievement of the 100% fT > MIC target was comparable across all antibiotics (~70%), but 100% fT > 4 MIC attainment was significantly higher for FEP (47.8%) than for TZP (10.3%) and MEM (30%) (p = 0.01). Supratherapeutic concentrations were observed in 34.8% of FEP users compared to 3.4% and 5% for TZP and MEM, respectively (p = 0.002). Neurotoxicity occurred in 13% of FEP patients but was not reported in TZP or MEM groups (p = 0.04). Subtherapeutic concentrations were noted in approximately 30% of patients across all groups.

Conclusion

PK changes complicate β-lactam antibiotic dosing, resulting in frequent failure to achieve PK/PD targets. FEP demonstrated a particularly high risk of supratherapeutic concentrations and neurotoxicity. Therapeutic drug monitoring is crucial to optimize dosing and improve safety in this population.

Population Pharmacokinetics-Based Evaluation of Ceftazidime-Avibactam Dosing Regimens in Critically and Non-Critically Ill Patients With Carbapenem-Resistant Klebsiella pneumoniae

Purpose

This study aimed to describe the population pharmacokinetics (PopPK) of ceftazidime-avibactam (CAZ-AVI) in adult patients, and to develop optimal dosing regimens for both non-critically ill and critically ill patients by combining different pharmacokinetic/pharmacodynamic (PK/PD) targets.

Patients and Methods

A prospective, single-center study involving patients who were infected with CRKP and received CAZ-AVI therapy was conducted. Nonlinear mixed-effect modeling was used to develop a PopPK model. The optimal dosing regimen was assessed using Monte Carlo simulation.

Results

The PopPK analysis of CAZ-AVI included 91 steady-state concentrations from 45 adult patients. The data were modeled using a one-compartment model. The typical population values of CAZ and AVI clearances were 2.96 L/h and 3.09 L/h, and the volumes of distribution were 17.76 L and 18.25 L, respectively. Our study showed that creatinine clearance (CrCL) calculated using the Cockcroft-Gault equation significantly affected the pharmacokinetics of CAZ-AVI. The Monte Carlo simulation optimized the dosing regimen for both non-critically ill and critically ill patients with varying renal functions, providing detailed supplements to the instructions.

Conclusion

Our study established a PopPK model for CAZ-AVI and proposed a reference for dosing regimen adjustment based on the severity of the disease and renal functional status.

Population Pharmacokinetics of Prolonged Infusion for Meropenem: Tailoring Dosing Recommendations for Chinese Critically Ill Patients on Continuous Renal Replacement Therapy with Consideration for Renal Function

Objective

Extended meropenem infusion is increasingly employed to enhance clinical outcomes in critically ill patients. Nonetheless, investigations into such dosing regimens in renal-impaired patients undergoing continuous renal replacement therapy (CRRT) are scarce. This study aims to perform a population pharmacokinetic (PK) analysis of prolonged meropenem infusion in critically ill CRRT patients to inform optimal dosing regimens.

Methods

Ninety-four concentrations from 21 Chinese critically ill CRRT patients receiving 1 g meropenem every 8-12 hours infused over 2-3 hours were utilized to construct the population PK model. Monte Carlo simulations were employed to assess the efficacy based on PK/PD targets (100% fT>MIC or 100% fT>4×MIC) and the risk of nephrotoxicity (trough concentration ≥45 mg/L) for extended meropenem dosing regimens (0.5-2 g with a 3-hour infusion administered every 6-12 hours).

Results

Meropenem concentration data was adequately described by a one-compartment model with linear elimination, and creatinine clearance (CLCR) significantly influenced meropenem's endogenous clearance. 0.5 g q6h and 1 g q8h could achieve desirable attainment of 100% fT>MIC target against an MIC≤4 mg/L, with negligible risk of toxicity for CRRT patients across a CLCR range of 10-50 mL/min. 2 g q6h and 2 g q8h is required for targeting 100% fT>4×MIC for the patients, but the associated risk of toxicity is very high (>20%).

Conclusion

A population PK model was developed for prolonged meropenem infusion in Chinese CRRT patients, and 0.5 g q6h and 1 g q8h may be the optimal regimen for prolonged infusion.

Interprofessional Therapeutic Drug Monitoring of Piperacillin/Tazobactam Enhances Care for Patients with Acute-on-Chronic Liver Failure in the ICU: A Retrospective Observational Pilot Study

Background: Acute-on-chronic liver failure (ACLF) is a severe, rapidly progressing syndrome in patients with liver cirrhosis, often triggered by bacterial infections. Piperacillin/Tazobactam is a key antibiotic in this setting, and therapeutic drug monitoring (TDM) helps optimize its dosing. This study evaluates the impact of an interprofessional TDM strategy for Piperacillin/Tazobactam in ACLF patients in the ICU. Methods: This retrospective ICU study evaluated an interprofessional TDM approach for optimizing Piperacillin/Tazobactam dosing in critically ill ACLF patients. The team, consisting of physicians, clinical pharmacists, and staff nurses, engaged in shared decision making, collaboratively interpreting TDM results and adjusting the dosing accordingly. This study included 26 patients with ACLF who underwent initial TDM and 7 who received follow-up TDM. Piperacillin/Tazobactam dosing was modified based on TDM recommendations, with serum concentrations measured weekly. Adherence to and the implementation of interprofessional dosing recommendations were systematically analyzed to assess the impact of this approach. Results: The initial TDM showed that 30.8% of patients had Piperacillin/Tazobactam levels within the target range, while 53.8% were above and 15.4% below. The interprofessional team recommended dose reductions in seven patients, increases in three, and no change in eleven, with five requiring antibiotic modifications. At the first follow-up TDM, 20.0% reached target levels, while 80.0% remained above, with no subtherapeutic cases. The team recommended one further dose reduction and maintained dosing in four patients. All recommendations were fully implemented, demonstrating strong adherence to the collaborative protocol. Conclusions: The interprofessional TDM strategy optimized Piperacillin/Tazobactam dosing in ACLF patients with full adherence to the recommendations. This collaborative approach improves outcomes and supports global efforts to curb antibiotic resistance.

Population pharmacokinetics of piperacillin-tazobactam in the plasma and cerebrospinal fluid of critically ill patients

Ventriculitis in neurocritical care patients leads to significant morbidity and mortality. Antibiotic dose optimization targeting pharmacokinetic/pharmacodynamic (PK/PD) exposures associated with improved bacterial killing may improve therapeutic outcomes. We sought to develop and apply a population PK model in infected critically ill patients to determine optimal piperacillin-tazobactam (PTZ) dosing regimens to achieve target cerebrospinal fluid (CSF) exposures. Neurosurgical patients with external ventricular drains and receiving PTZ treatment were recruited and had plasma and CSF samples collected and assayed. A population PK model was developed using plasma and CSF piperacillin and tazobactam concentrations. Eight patients were recruited. Median age was 59 years, median weight was 70 kg, and five patients were female. The median creatinine clearance was 84 mL/min/1.73 m2 (range 52-163). Substantial inter-individual PK variability was apparent, particularly in CSF. Piperacillin penetration into CSF had a median of 3.73% (range 0.73%-7.66%), and tazobactam CSF penetration was not predictable. Dosing recommendations to optimize CSF exposures for the treatment of ventriculitis were not possible due to substantial PK variability and very low drug penetration. High plasma PTZ exposures may not translate to effective exposures in CSF.

Suggested Dosing of Select Beta-lactam Agents for the Treatment of Antimicrobial-Resistant Gram-Negative Infections in Children

The Infectious Diseases Society of America (IDSA) publishes annual guidance on the treatment of antimicrobial-resistant (AMR) gram-negative infections. Within the AMR guidance, suggested dosages of antibiotics for adults infected with AMR pathogens are provided. This document serves as a companion document to the IDSA guidance to assist pediatric specialists with dosing β-lactam agents for the treatment of AMR infections in children. A panel of 13 pediatric infectious diseases specialists, including 11 pharmacists and 2 physicians, reviewed existing pharmacokinetic/pharmacodynamic, animal, and clinical data for newer β-lactam agents that are available in the United States and suggested for the treatment of AMR infections (ie, cefiderocol, ceftazidime-avibactam, ceftazidime-avibactam and aztreonam, ceftolozane-tazobactam, imipenem-cilastatin-relebactam, meropenem-vaborbactam, sulbactam-durlobactam). Suggested dosing for ampicillin-sulbactam is also provided, given complexities in dosing for carbapenem-resistant Acinetobacter baumannii infections. Consensus-based suggested dosing for β-lactam agents used to treat AMR infections in neonates, infants, children, and adolescents and relevant supporting evidence are provided. Content is up to date as of December 1, 2024. Gaps and limitations to existing data are discussed. Optimizing antibiotic dosing is critical to improving the outcomes of children with AMR infections.

'Real-life' approach to applying PK/PD principles in infectious diseases clinical practice without access to prompt TDM

INTRODUCTION

Infectious disease treatments are transitioning from a one-size-fits-all approach to a more tailored approach. The increasing adoption of therapeutic drug monitoring (TDM) of antimicrobials is a clear example of this trend. Routine antimicrobial TDM in critically ill patients should be mandatory. Unfortunately, nowadays, only expert centers can provide it. Given the crucial nature of the first hours/days for achieving a favorable clinical outcome, empirical antibiotic therapy with an adequate choice of drug, dose and administration modalities is fundamental.

AREAS COVERED

We outline common scenarios encountered in clinical practice, such as in edematous patients, hypoalbuminemia, patients with liver and renal diseases, patients under renal replacement therapy or extracorporeal membrane oxygenation (ECMO), over or under-weight patients, in old adults and cases of infections caused by relatively high minimum inhibitory concentration (MIC) pathogens. Various clinical situations were analyzed with the help of the available literature (PubMed/MEDLINE/Google Scholar and books written by experts in pharmacology and infectious diseases).

EXPERT OPINION

In these different scenarios, we reported common examples of optimizing drug utilization to maximize therapeutic outcomes, reduce incorrect prescriptions and limit the emergence of antimicrobial resistance.

Efficacy of extended infusion of β-lactam antibiotics for the treatment of febrile neutropenia in haematologic patients (BEATLE): a randomized, multicentre, open-label, superiority clinical trial

OBJECTIVES

The efficacy of extended infusions (EI) of β-lactam antibiotics for optimising outcomes in febrile neutropenia is unclear. We assessed whether the administration of β-lactams was more effective in EI than in intermittent infusion (II) for the treatment of febrile neutropenia.

METHODS

We performed a randomized, open-label, superiority clinical trial of patients with febrile neutropenia at four Spanish university hospitals. Patients undergoing haematopoietic stem cell transplantation or with acute leukaemia receiving chemotherapy who required empirical antibiotic treatment for febrile neutropenia were randomly assigned (1:1) to receive EI of β-lactam or II after a first dose in bolus. The choice of antipseudomonal β-lactam was left to the discretion of the attending physician. The primary endpoint was treatment success at day 5, defined as defervescence without modifying the antibiotic treatment. Secondary endpoints included adverse events, attainment of the pharmacokinetic/pharmacodynamic target of 50%, 75%, and 100%ƒuT > MIC, and 30-day mortality.

RESULTS

From November 19, 2019 to June 22, 2022, 295 patients were screened for eligibility, of whom 150 were randomly assigned to receive EI (n = 77) or II (n = 73) of the antipseudomonal β-lactam of choice. In the intention-to-treat analysis, treatment success at day 5 was achieved in 39/77 patients (50.6%) receiving EI versus 46/73 patients (63.0%) receiving II (risk difference, -12.4%; 95% CI, -29.4 to 4.7; p 0.17). The pharmacokinetic/pharmacodynamic targets of 75% and 100% ƒuT > MIC for empirical treatment were achieved more frequently in the EI group. No statistically significant differences were found between groups in terms of adverse events or 30-day mortality.

DISCUSSION

Our findings do not support the routine use of empirical EI of β-lactams in febrile neutropenia. Further studies should consider the clinical heterogeneity of febrile neutropenia and focus on patients with sepsis or septic shock and microbiologically documented infections, particularly those with infections caused by microorganisms less susceptible to β-lactams.

Are contemporary antifungal doses sufficient for critically ill patients? Outcomes from an international, multicenter pharmacokinetics study for Screening Antifungal Exposure in Intensive Care Units-the SAFE-ICU study

PURPOSE

Appropriate antifungal therapy is a major determinant of survival in critically ill patients with invasive fungal disease. We sought to describe whether contemporary dosing of antifungals achieves therapeutic exposures in critically ill patients.

METHODS

In a prospective, open-label, multicenter pharmacokinetic study, intensive care unit (ICU) patients prescribed azoles, echinocandins, or polyene antifungals for treatment or prophylaxis of invasive fungal disease were enrolled. Blood samples were collected on two occasions, with three samples taken during a single dosing interval on each occasion. Total concentrations were centrally measured using validated chromatographic methods. Pharmacokinetic parameters were estimated using noncompartmental methods. Antifungal dosing adequacy was assessed using predefined PK/PD targets.

RESULTS

We included 339 patients from 30 ICUs across 12 countries. Median age 62 (interquartile range [IQR], 51-70) years, median APACHE II score 22 (IQR, 17-28), and 61% males. Antifungal therapy was primarily prescribed for treatment (80.8%). Fluconazole was the most frequently prescribed antifungal (40.7%). The most common indication for treatment was intra-abdominal infection (30.7%). Fungi were identified in 45% of patients, of which only 26% had a minimum inhibitory concentration available. Target attainment was higher for patients receiving prophylaxis (> 80% for most drugs). For patients receiving treatment, low target attainment was noted for voriconazole (57.1%), posaconazole (63.2%), micafungin (64.1%) and amphotericin B (41.7%).

CONCLUSION

This study highlights the varying degrees of target attainment across antifungal agents in critically ill patients. While a significant proportion of patients achieved the predefined PK/PD targets, wide variability and subtherapeutic exposures persist.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03136926, 2017-04-21.

Target attainment of beta-lactam antibiotics and ciprofloxacin in critically ill patients and its association with 28-day mortality

OBJECTIVES

This study aims to assess pharmacodynamic target attainment in critically ill patients and identify factors influencing target attainment and mortality outcomes.

METHODS

We analysed data from the DOLPHIN trial. Beta-lactam and ciprofloxacin peak and trough concentration were measured within the first 36 h (T1) after initiation of treatment. The study outcome included the rate of pharmacodynamic target attainment of 100 % ƒT>1xEpidemiological cut-off value (ECOFF) for beta-lactams, and of fAUC0-24h/ECOFF>125 for ciprofloxacin at T1.

RESULTS

The target attainment rates were 78.1 % (n = 228/292) for beta-lactams, and 41.5 % (n = 39/94) for ciprofloxacin, respectively. Lower estimated glomerular filtration rate and higher SOFA score were associated with target attainment. In patients receiving beta-lactams, 28-day mortality was significantly higher in patients who attained 100 % ƒT>1xECOFF (28.9 % vs. 12.5 %; p = 0.01). In the multivariate analysis, attainment of 100 % ƒT>4xECOFF, but not 100 % ƒT>1xECOFF, was associated with a higher 28-day mortality (OR 2.70, 95 % CI 1.36-5.48 vs. OR 1.28, 95 % CI 0.53-3.34).

CONCLUSIONS

A high rate of target attainment (100 % ƒT>1xECOFF) for beta-lactams and a lower rate for ciprofloxacin was observed. Achieving exposures of 100 % ƒT>4xECOFF was associated with 28-day mortality. The impact of antibiotic target attainment on clinical outcome needs to be a focus of future research.

Cost-effectiveness of data driven personalised antibiotic dosing in critically ill patients with sepsis or septic shock

PURPOSE

This study provides an economic evaluation of bedside, data-driven, and model-informed precision dosing of antibiotics in comparison with usual care among critically ill patients with sepsis or septic shock.

METHODS

This economic evaluation was conducted alongside an AutoKinetics randomized controlled trial. Effect measures included quality-adjusted life years (QALYs), mortality and pharmacokinetic target attainment. Costs were measured from a societal perspective. Missing data was multiply imputed, and bootstrapping was used to estimate statistical uncertainty. Differences in effects and costs were estimated using bivariate regression and used to calculate incremental cost-effectiveness ratios.

RESULTS

Patients in the intervention group had higher costs (€42,684 vs. 39,475), lower mortality (42% vs. 49%), more QALYs (0.184 vs. 0.153), and higher pharmacokinetic target attainment (69% vs. 48%). Only the difference for target attainment was found statistically significant. An additional €18,129, €55,576, and €123,493 needs to be invested to attain the targeted plasma levels for one more patient, to save one life and gain one QALY, respectively. The probability of cost-effectiveness for all effect outcomes is below 60% for most acceptable willingness-to-pay thresholds.

CONCLUSIONS

Data-driven personalised antibiotic dosing in critically ill patients as implemented in the AutoKinetics trial cannot be recommended for implementation as a cost-effective intervention.

TRIAL REGISTRATION

The trial was prospectively registered at Netherlands Trial Register (NTR), NL6501/NTR6689 on 25 August 2017 and at the European Clinical Trials Database (EudraCT), 2017-002478-37 on 6 November 2017.

Therapeutic drug monitoring (TDM) of β-lactam/β-lactamase inhibitor (BL/BLI) drug combinations: insights from a pharmacometric simulation study

BACKGROUND

The emergence of β-lactamase-producing bacteria has led to the use of β-lactam (BL) antibiotic and β-lactamase inhibitor (BLI) drug combinations. Despite therapeutic drug monitoring (TDM) being endorsed for BLs, the impact of TDM on BLIs remains unclear.

OBJECTIVES

Evaluate whether BLIs are available in effective exposures at the site of infection and assess if TDM of BLIs could be of interest.

METHODS

Population pharmacokinetic models for 9 BL and BLI compounds were used to simulate drug concentrations at infection sites following EMA-approved dose regimens, considering plasma protein binding and tissue penetration. Predicted target site concentrations were used for probability of target attainment (PTA) analysis.

RESULTS

Using EUCAST targets, satisfactory (≥90%) PTA was observed for BLs in patients with typical renal clearance (CrCL of 80 mL/min) across various sites of infection. However, results varied for BLIs. Avibactam achieved satisfactory PTA only in plasma, with reduced PTAs in abdomen (78%), lung (73%) and prostate (23%). Similarly, tazobactam resulted in unsatisfactory PTAs in intra-abdominal infections (79%), urinary tract infections (64%) and prostatitis (34%). Imipenem-relebactam and meropenem-vaborbactam achieved overall satisfactory PTAs, except in prostatitis and high-MIC infections for the latter combination.

CONCLUSIONS

This study highlights the risk of solely relying on TDM of BLs, as this can indicate acceptable exposures of the BL while the BLI concentration, and consequently the combination, can result in suboptimal performance in terms of bacterial killing. Thus, dose adjustments also based on plasma concentration measurements of BLIs, in particular for avibactam and tazobactam, can be valuable in clinical practice to obtain effective exposures at the target site.

Piperacillin/Tazobactam Susceptibility Test Interpretive Criteria for Enterobacterales: Recommendations From the United States Committee on Antimicrobial Susceptibility Testing

The in vitro susceptibility testing interpretive criteria (STIC) for piperacillin/tazobactam (TZP) against Enterobacterales were recently updated by the US Food and Drug Administration, Clinical and Laboratory Standards Institute, and European Committee on Antimicrobial Susceptibility Testing. The United States Committee on Antimicrobial Susceptibility Testing (USCAST) also recently reviewed TZP STIC for Enterobacterales and arrived at different STIC for Enterobacterales. Here, we explain our recommendations and rationale behind them. Based on our review of the available data, USCAST does not recommend TZP STIC for certain Enterobacterales species that have a moderate to high likelihood of clinically significant AmpC production (Enterobacter cloacae, Citrobacter freundii, and Klebsiella aerogenes only) or for third-generation cephalosporin-nonsusceptible Enterobacterales. USCAST recommends a TZP susceptibility breakpoint of ≤ 16/4 mg/L for third-generation cephalosporin-susceptible Enterobacterales and only endorses the use of extended infusion TZP regimens for patients with infections due to these pathogens.

In vitro elimination of antimicrobials during ADVanced Organ Support hemodialysis

Background

Acute kidney injury (AKI) requiring continuous renal replacement therapy is common in critically ill patients. The ADVanced Organ Support (ADVOS) system is a novel hemodialysis machine that uses albumin enriched dialysate which allows the removal of protein-bound toxins and drugs. To date, data on antimicrobial removal under ADVOS has not yet been reported.

Methods

An in vitro study was conducted using whole porcine blood and continuous infusions of different antimicrobial agents to investigate the effect of ADVOS on drug exposure. Drugs with varying protein binding, molecular weights and renal clearances, anidulafungin, cefotaxime, daptomycin, fluconazole, ganciclovir, linezolid, meropenem and piperacillin were studied.

Results

All studied drugs were removed during the in vitro ADVOS experiment. Clearance under ADVOS (CLADVOS) for low protein-bound drugs, such as cefotaxime, fluconazole, ganciclovir, linezolid, meropenem and piperacillin ranged from 2.74 to 3.4 L/h at a blood flow of 100 mL/min. With a doubling of flow rate CL for these drugs increased. Although efficiently removed, this effect was not seen for CLADVOS in high protein-bound substances such as daptomycin (1.36 L/h) and anidulafungin (0.84 L/h).

Conclusion

The ADVOS system effectively removed protein-bound and unbound antimicrobials to a significant extent indicating that dose adjustments are required. Further, clinical studies are necessary to comprehensively assess the impact of ADVOS on antimicrobial drug removal. Until clinical data are available, therapeutic drug monitoring should guide antimicrobial dosing under ADVOS.

Employing artificial intelligence for optimising antibiotic dosages in sepsis on intensive care unit: a study protocol for a prospective observational study (KI.SEP)

INTRODUCTION

In sepsis treatment, achieving and maintaining effective antibiotic therapy is crucial. However, optimal antibiotic dosing faces challenges due to significant variability among patients with sepsis. Therapeutic drug monitoring (TDM), the current gold standard, lacks initial dosage adjustments and global availability. Even with daily TDM, antibiotic serum concentrations (ASCs) often deviate from the therapeutic range. This study addresses these challenges by developing machine learning (ML)-based ASC prediction models capable of handling variable data input and encompassing diverse clinical, laboratory, microbiological and proteomic parameters without the need for daily TDM.

METHODS

This prospective observational study is conducted in a German university hospital intensive care unit. Eligible sepsis patients receive continuous antibiotic therapy with piperacillin/tazobactam (n=100) or meropenem (n=100) within 24 hours. Exclusion criteria include refusal, pregnancy, lactation and severe anaemia (haemoglobin <8 g/dL). Blood samples for TDM are collected from patients, along with clinical and laboratory parameters on days 1-8 and day 30 or on discharge. ML models predicting ASC between day 1 and day 8 serve as primary and key secondary endpoints. We will use the collected data to develop multifaceted ML-based algorithms aimed at optimising antibiotic dosing in sepsis. Our two-way approach involves creating two distinct algorithms: the first focuses on predictive accuracy and generalisability using routine clinical parameters, while the second leverages an extended dataset including a plethora of factors currently insufficiently explored and not available in standard clinical practice but may help to enhance precision. Ultimately, these models are envisioned for integration into clinical decision support systems within patient data management systems, facilitating automated, personalised treatment recommendations for sepsis.

ETHICS AND DISSEMINATION

The study received approval from the Ethics Committee of the Medical Faculty of Ruhr-University Bochum (No. 23-7905). Findings will be disseminated through open-access publication in a peer-reviewed journal and social media channels.

TRIAL REGISTRATION NUMBER

DRKS00032970.

Pharmacodynamic target attainment at infection site during treatment of post-neurosurgical ventriculitis caused by carbapenem-resistant klebsiella pneumoniae with ceftazidime-avibactam-based regimens: a case report

A patient developed a post-neurosurgical ventriculitis with carbapenem-resistant Klebsiella pneumoniae and mold, initially treated with ceftazidime/avibactam and voriconazole. A Klebsiella pneumoniae carbapenemase mutation led to therapy adjustment to ceftazidime/avibactam and polymyxin B, achieving cure. Pharmacokinetic/pharmacodynamic analysis highlights effective ceftazidime/avibactam brain penetration and bacterial clearance efficacy.

Prolonged Beta-Lactam Infusions in Children: A Systematic Review and Meta-Analysis

OBJECTIVE

To assess whether beta-lactam extended or continuous beta-lactam infusions (EI/CI) improve clinical outcomes in children with proven or suspected bacterial infections.

STUDY DESIGN

We included observational and interventional studies that compared beta-lactam EI or CI with standard infusions in children less than 18 years old, and reported on mortality, hospital or intensive care unit length of stay, microbiological cure, and/or clinical cure. Data sources included PubMed, Medline, EBM Reviews, EMBASE, and CINAHL and were searched from January 1, 1980, to November 3, 2023. Thirteen studies (2945 patients) were included: 5 randomized control trials and 8 observational studies. Indications for antimicrobial therapies and clinical severity varied, ranging from cystic fibrosis exacerbation to critically ill children with bacteriemia.

RESULTS

EI and CI were not associated with a reduction in mortality in randomized control trials (n = 1464; RR 0.93, 95% CI 0.71, 1.21), but were in observational studies (n = 833; RR 0.43, 95% CI 0.19, 0.96). We found no difference in hospital length of stay. Results for clinical and microbiological cures were heterogeneous and reported as narrative review. The included studies were highly heterogeneous, limiting the strength of our findings. The lack of shared definitions for clinical and microbiological cure outcomes precluded analysis.

CONCLUSIONS

EI and CI were not consistently associated with reduced mortality or length of stay in children. Results were conflicting regarding clinical and microbiological cures. More well-designed studies targeting high-risk populations are necessary to determine the efficacy of these alternative dosing strategies.

A review of antimicrobial stability testing guidance for outpatient parenteral antimicrobial therapy programmes: is it time for global harmonization of testing frameworks?

Antimicrobial stability is an important consideration for treatment planning and service delivery in outpatient parenteral antimicrobial therapy (OPAT) programmes. Regulation of stability assessment varies by region, and conflicting guidance and standards exist. This leads to disparity of equity in access and limits availability of certain antimicrobials for managing infections in the outpatient setting. This review discusses the degree to which the international regulatory bodies have reached consensus on the regulation of antimicrobial stability testing, specifically for OPAT, and describes the variation in antimicrobial recommendations across regulatory bodies. The three major findings in this review are (i) variation in antimicrobial stability testing guidance, particularly in relation to temperature; (ii) lack of regulatory guidance, specifically in that some regions did not have OPAT guidelines; and (iii) only the UK's NHS has provided non-regulatory OPAT-specific advice on antimicrobial stability testing. In conclusion, harmonization of antimicrobial stability testing to form a global OPAT-specific regulatory framework, particularly considering 'areas of variation' amongst current guidance, is required. We call for the development of a global OPAT antimicrobial stability testing framework with consensus from accepted antimicrobial stability criteria, expert opinion and pharmacopoeial best practice.

A retrospective cohort analysis of factors influencing continuous antibiotic therapy with ampicillin

AIMS

There are limited data on ampicillin/sulbactam, both for continuous infusion and for use in critically ill patients. We aimed to identify factors that help predict ampicillin plasma levels during continuous antibiotic therapy in intensive care patients.

MAIN METHODS

We retrospectively reviewed and retrieved a large dataset of patients who received continuous ampicillin infusion with therapeutic drug monitoring between 2015 and 2022. Patients initially received standard dosing (single shot of 2/1 g followed by continuous infusion of 6/3 g ampicillin/sulbactam per day), which was then adjusted based on the results of regular therapeutic drug monitoring and according to a target range of 30-60 mg/l (equivalent to four to eight times the minimum inhibitory concentration of ampicillin for Enterobacterales).

MAIN RESULTS

466 measurements from 225 patients (152 male, mean age 61 years) were analyzed. Initial measurements of ampicillin plasma levels were below the predefined optimal therapeutic range in 50 %, within the range in 30 % and above the range in 20 %. Target attainment increased to 70 % by the 4th measurement. There was a significant negative correlation between ampicillin plasma levels and estimated glomerular filtration rate (eGFR) (r = -0.74; p < 0.001) and, to a lesser extent, with height (r = -0.31; p < 0.001). Based on multiple linear regression, eGFR and body weight or height were the factors accounting for 63 % of the variability in the data.

SIGNIFICANCE

To optimise target achievement, ampicillin dosing in critically ill patients requires a personalized approach based on renal function. Importantly, patients with normal or augmented eGFR require higher standard doses of ampicillin/sulbactam.

Physiologically-based pharmacokinetic modelling in sepsis: A tool to elucidate how pathophysiology affects meropenem pharmacokinetics

OBJECTIVES

Applying physiologically-based pharmacokinetic (PBPK) modelling in sepsis could help to better understand how PK changes are influenced by drug- and patient-related factors. We aimed to elucidate the influence of sepsis pathophysiology on the PK of meropenem by applying PBPK modelling.

METHODS

A whole-body meropenem PBPK model was developed and evaluated in healthy individuals, and renally impaired non-septic patients. Sepsis-induced physiological changes in body composition, organ blood flow, kidney function, albumin, and haematocrit were implemented according to a previously proposed PBPK sepsis model. Model performance was evaluated, and a local sensitivity analysis was conducted.

RESULTS

The model-predicted PK metrics (AUC, Cmax, CL, Vss) were within 1.33-fold-error margin of published data for 87.5% of the simulated profiles in healthy individuals. In sepsis, the model provided good predictions for literature-digitised average plasma and tissue exposure data, where the model-predicted AUC was within 1.33-fold-error margin for 9 out 11 simulated study profiles. Furthermore, the model was applied to individual plasma concentration data from 52 septic patients, where the model-predicted AUC, Cmax, and CL had a fold-error ratio range of 0.98-1.12, with alignment of the predicted and observed variability. For Vss, the fold-error ratio was 0.81, and the model underpredicted the population variability. CL was sensitive to renal plasma clearance, and kidney volume, whereas Vss was sensitive to the unbound fraction, organ volume fraction of the interstitial compartment, and the organ volume.

CONCLUSIONS

These findings may be extended to more diverse drug types and support a more mechanistic understanding of the effect of sepsis on drug exposure.

Pharmacokinetic Factors Associated With Early Meropenem Target Attainment in Pediatric Severe Sepsis

OBJECTIVES

To determine the frequency of early meropenem concentration target attainment (TA) in critically ill children with severe sepsis; to explore clinical, therapeutic, and pharmacokinetic factors associated with TA; and to assess how fluid resuscitation and volume status relate to early TA.

DESIGN

Retrospective analysis of prospective observational cohort study.

SETTING

PICU in a single academic quaternary care children's hospital.

PATIENTS

Twenty-nine patients starting meropenem for severe sepsis (characterized as need for positive pressure ventilation, vasopressors, or ≥ 40 mL/kg bolused fluid), of which 17 were newly escalated to PICU level care.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Concentration-time profiles were analyzed using modeling software employing opportunistic sampling, Bayesian estimation, and a population pharmacokinetic model. Time above four times minimum inhibitory concentration (T > 4×MIC), using the susceptibility breakpoint of 1 µg/mL, was determined for each patient over the first 24 hours of meropenem therapy, as well as individual clearance and volume of distribution (Vd) estimates. Twenty-one of 29 patients met a target of 40%T > MIC 4 μg/mL. Reaching TA, vs. not, was associated with lower meropenem clearance. We failed to identify a difference in Vd or an association between the TA group and age, weight, creatinine-based estimated glomerular filtration rate (eGFR), or the amount of fluid administered. eGFR was, however, negatively correlated with overall T > MIC.

CONCLUSIONS

Eight of 29 pediatric patients with early severe sepsis did not meet the selected TA threshold within the first 24 hours of meropenem therapy. Higher clearance was associated with failure to meet targets. Identifying patients likely to have higher meropenem clearance could help with dosing regimens.

SIL-IS LC-ESI-MS/MS method for simultaneous quick detection of amoxicillin and clavulanic acid in human plasma: Development, validation and its application to a pharmacokinetics study

A liquid chromatography electrospray ionization tandem mass spectrometry method with amoxicillin-d4 as the stable isotope-labeled internal standard for simultaneous quick detection of amoxicillin and clavulanic acid in human plasma was developed and validated. Chromatographic separations were performed on a Hedera ODS-2 column (2.1 × 150 mm, 5 μm). The mobile phases for gradient elution were aqueous solution containing 0.2% acetic acid (AA) (mobile phase A) together with organic phase solution (acetonitrile and methanol mixed solution, mobile phase B). Mass spectrometry was performed using negative electrospray ionization in multiple reaction monitoring mode. The target fragment ion pairs of amoxicillin, clavulanic acid and amoxicillin-d4 were m/z 364.1 → 223.1, 198.1 → 135.9 and 368.1 → 227.1, respectively. The linear ranges of this method were 40-5,000 ng/ml for amoxicillin and 30-2,500 ng/ml for clavulanic acid, with coefficient of determination > 0.9900. This method validation included selectivity, standard curve, lower limit of quantitation, accuracy, precision, recovery, matrix effect (hemolytic matrix and hyperlipidemic matrix), carryover, stability, dilution reliability and incurred sample reanalysis study. A successful application of this method was realized in a pharmacokinetic study after administration of amoxicillin-clavulanic acid potassium granules.