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Infections with multidrug resistant Acinetobacter baumannii in immunocompromised patients are life-threatening. Therapeutic options are rare in this context, but patients are dependent on an effective antibiotic therapy. Thus, new antibiotic strategies are deemed necessary. This case report recounts the therapeutic drug monitoring-guided meropenem therapy of a 32 years old patient admitted with acute exacerbation of cystic fibrosis. Veno-venous extracorporeal membrane oxygenation was initiated on the first day of admission to the intensive care unit. The patient showed insufficient serum trough levels of meropenem despite the maximum approved dose (2g every 8h) was administered which was due to augmented renal clearance. Through continuous infusion of the same cumulative dose, target levels were reached. On day 17 of admission, the patient underwent successful double-lung-transplant surgery and extracorporeal membrane oxygenation was ended. Unfortunately, the donor's lung was colonized with a multidrug resistant Acinetobacter baumannii that was positive for OXA-23 carbapenemase. Hence a combination therapy of intravenous sulbactam, tigecycline, meropenem and inhalative colistin was established, with a known minimal inhibitory concentration for meropenem of 32 mg/l. Under continuous infusion of 8 g meropenem/day, serum levels exceeded 32 mg/l over 12 days. The patient was transferred from the intensive care unit to a general ward without any signs of infection. Therapeutic drug monitoring-guided meropenem may be a sound new therapeutic option in eradicating multidrug resistant Acinetobacter and offer a novel therapeutic option in the field of personalized medicine. [ABSTRACT FROM AUTHOR]

Objectives: Piperacillin (PIP)/tazobactam is a frequently prescribed antibiotic; however, over- or underdosing may contribute to toxicity, therapeutic failure, and development of antimicrobial resistance. An external evaluation of 24 published PIP-models demonstrated that model-informed precision dosing (MIPD) can enhance target attainment. Employing various candidate models, this study aimed to assess the predictive performance of different MIPD-approaches comparing (i) a single-model approach, (ii) a model selection algorithm (MSA) and (iii) a model averaging algorithm (MAA)., Methods: Precision, accuracy and expected target attainment, considering either initial (B1) or initial and secondary (B2) therapeutic drug monitoring (TDM)-samples per patient, were assessed in a multicentre dataset (561 patients, 11 German centres, 3654 TDM-samples)., Results: The results demonstrated a slight superiority in predictive performance using MAA in B1, regardless of the candidate models, compared to MSA and the best single models (MAA, MSA, best single models: inaccuracy ±3%, ±10%, ±8%; imprecision: <25%, <31%, <28%; expected target attainment >77%, >71%, >73%). The inclusion of a second TDM-sample notably improved precision and target attainment for all MIPD-approaches, particularly within the context of MSA and most of the single models. The expected target attainment is maximized (up to >90%) when the TDM-sample is integrated within 24 h., Conclusions: In conclusion, MAA streamlines MIPD by reducing the risk of selecting an inappropriate model for specific patients. Therefore, MIPD of PIP using MAA implicates further optimisation of antibiotic exposure in critically ill patients, by improving predictive performance with only one sample available for Bayesian forecasting, safety, and usability in clinical practice., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Bilirubin is one of the most frequently used laboratory values to monitor critically ill patients with cholestatic liver dysfunction. Besides bilirubin, toxic bile acids (TBAs), which may cause severe organ damage, are typically elevated. A correlation between both parameters seems plausible, but data are lacking. The aim was to investigate whether there is a correlation between bilirubin and TBAs in patients' blood and whether a compareable reduction can be observed during the use of the adsorber CytoSorb (CS). As part of the Cyto-SOLVE study (NCT04913298), 16 critically ill patients with cholestatic liver dysfunction, bilirubin concentration > 10 mg/dl, continuous kidney replacement therapy and CS-application were investigated. Bilirubin and TBA concentrations were measured from arterial blood at defined time points (before start, after 6 and 12 h). Relative reduction (RR) was calculated using the formula[Formula: see text]. A moderate to high correlation between bilirubin and TBA concentration at all defined timepoints (r start =0.64, p = 0.008; r 6h  = 0.85, p < 0.001, r 12h  = 0.72, p = 0.002) was observed. In the first six hours of CS-application, a significant elimination of TBA (median TBA: 30.8→20.1µmol/l, p < 0.001) and bilirubin (median bilirubin: 17.1→11.9 mg/dl, p < 0.001) was observed. The median RR after 6 h was 26.1% and 39.8% for bilirubin and TBA, respectively. No further reduction was observed after 12 h (RR bilirubin : - 0.6%, RR TBA : 1.8%). There was an at least moderate correlation between bilirubin and TBA in patients with cholestatic liver dysfunction. Therefore, bilirubin seems to be a suitable surrogate parameter for TBA elimination during CytoSorb application., (© 2024. The Author(s).)

Meropenem penetration into the cerebrospinal fluid (CSF) is subject to high interindividual variability resulting in uncertain target attainment in CSF. Recently, several authors recommended administering meropenem as a continuous infusion (CI) to optimize CSF exposure. This study aimed to compare the concentrations and pharmacokinetics of meropenem in CSF after intermittent infusion (II) and CI. This prospective, observational study (NCT04426383) included critically ill patients with external ventricular drains who received either II or CI of meropenem. Meropenem pharmacokinetics in plasma and CSF were characterized using population pharmacokinetic modeling (NONMEM 7.5). The developed model was used to compare the concentration-time profile and probability of target attainment (PTA) between II and CI. A total of 16 patients (8 CI, 8 II; samples: n plasma = 243, n CSF = 263) were recruited, with nine patients (5 CI, 4 II) suffering from cerebral and seven patients from extracerebral infections. A one-compartment model described the plasma concentrations adequately. Meropenem penetration into the CSF (partition coefficient (KP), c CSF /c plasma ) was generally low (6.0%), exhibiting substantial between-subject variability (coefficient of variation: 84.0%). There was no correlation between the infusion mode and KP, but interleukin (IL)-6 measured in CSF showed a strong positive correlation with KP ( P < 0.001). Dosing simulations revealed no relevant differences in CSF concentrations and PTA in CSF between CI and II. Our study did not demonstrate increased penetration rates or higher concentrations of meropenem in the CSF with CI compared with II., Clinical Trials: This study is registered with ClinicalTrials.gov as NCT04426383., Competing Interests: S.G.W. received research support from Boehringer Ingelheim and AqVida GmbH; consultancy fees from Medicine for Malaria Venture, Utility Therapeutics, and Merck KGaA; and speaker honoraria from GlaxoSmithKline. C.S. received speaker honoraria from CytoSorbents Europe GmbH. M.Z. received research support from CytoSorbents Europe GmbH, consulting fees from Gilead, and speaker honoraria from MSD. U.L. received consulting honoraria from CytoSorbents Europe GmbH and was part of an advisory board of Roche Diagnostics International Ltd. All other authors declare no conflict of interest.

Introduction: The release of pro-inflammatory cytokines in critically ill patients with sepsis leads to endothelial dysfunction resulting in cardiocirculatory insufficiency. Their extracorporeal elimination using the cytokine adsorber CytoSorb ® (CS) (adsorption of especially hydrophobic molecules < 60 kDa) might be promising, but data about the adsorption capacity as well as a potential harmful adsorption of anti-inflammatory cytokines are missing so far., Methods: The prospective Cyto-SOLVE-study included 15 patients with sepsis or other hyperinflammatory conditions (interleukin 6 > 500 pg/ml), continuous kidney replacement therapy, and the application of CS. Various cytokines and chemokines were measured pre- and post-CS as well as in patients' blood at predefined timepoints. Significant changes in the concentrations were detected with the Wilcoxon test with associated samples. Clearance of the adsorber (ml/min) was calculated with: b l o o d f l o w ∗ c o n c e n t r a t i o n p r e - p o s t c o n c e n t r a t i o n pre . RESULTS: Most of the inflammatory mediators showed a high initial extracorporeal clearance of 70-100 ml/min after CS installation, which dropped quickly to 10-30 ml/min after 6 h of treatment. No difference in clearance was observed between pro- and anti-inflammatory cytokines. Despite extracorporeal adsorption, a significant (p < 0.05) decrease in the blood concentration after 6 h was only observed for the pro-inflammatory cytokines tumor necrosis factorα (TNF-α) (median 284 vs. 230 pg/ml), vascular endothelial growth factor (VEGF) (median 294 vs. 252 pg/ml), macrophage inflammatory protein 1a (MIP-1a) (median 11.1 vs. 9.0 pg/ml), and regulated upon activation, normal T cell expressed and secreted (RANTES) (median 811 vs. 487 pg/ml) as well as the anti-inflammatory cytokines interleukin 4 (median 9.3 vs. 6.4 pg/ml), interleukin 10 (median 88 vs. 56 pg/ml), and platelet-derived growth factor (PDGF) (median 177 vs. 104 pg/ml). A significant (p < 0.05) decrease in patients' blood after 12 h was only detected for interleukin 10., Conclusions: CS can adsorb pro- as well as anti-inflammatory mediators with no relevant difference regarding the adsorption rate. A fast saturation of the adsorber resulted in a rapid decrease of the clearance. The potential clinical benefit or harm of this unspecific cytokine adsorption needs to be evaluated in the future., Trial Registration: ClinicalTrials.gov NCT04913298, registration date June 4, 2021., (© 2024. The Author(s).)

Background: The inotropic drug levosimendan is often used as an individualized therapeutic approach perioperatively in cardiac surgery patients with cardiopulmonary bypass (CPB). Data regarding serum concentrations of levosimendan and its metabolites within this context is lacking., Methods: In this retrospective descriptive proof-of-concept study, total serum concentrations (TSC) and unbound fractions (UF) of levosimendan and its metabolites OR-1896 and OR-1855 in cardiac surgery patients with CPB were measured using LC-ESI-MS/MS. Simulation of expected levosimendan TSC was performed using Pharkin 4.0. Serum NT-proBNP was assessed with ELISA., Results: After levosimendan infusion (1.25 mg or 2.5 mg, respectively) after anaesthesia induction, a median TSC of 1.9 ng/ml and 10.4 ng/ml was determined in samples taken directly after surgery (T1). Median TSC of 7.6 ng/ml and 22.0 ng/ml, respectively, were simulated at T1. Whereas 1.1 ng/ml and 1.6 ng/ml TSC of OR-1896, respectively, was quantified the day after surgery (T2), TSC of the intermediate metabolite OR-1855 was mostly below the lower limit of quantification (LLOQ). The UF was 0.5% and 1.1% for levosimendan and 64.1% and 52.1% for OR-1896, respectively, with over half the samples being below LLOQ. NT-proBNP concentrations before surgery and T2 did not differ., Discussion: The low TSC, UF and unchanged NT-proBNP levels in combination with high variation of serum levels between patients suggest a need for optimized dosing regimen of levosimendan combined with therapeutic drug monitoring for such an individualized approach. In addition, the differences between the measured and estimated concentrations may suggest a possible influence of CPB on levosimendan serum concentrations., Competing Interests: HM and RT signed a Material Transfer Agreement with Orion Pharma for the use of the internal standards for the LC-ESI-MS/MS measurements. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Kipka, Liebchen, Hübner, Höfner, Frey, Wanner, Kilger, Hagl, Tomasi and Mannell.)

Background and Objectives: Precision dosing requires selecting the appropriate population pharmacokinetic model, which can be assessed through external evaluations (EEs). The lack of understanding of how different study design factors influence EE study outcomes makes it challenging to select the most suitable model for clinical use. This study aimed to evaluate the impact of sample size, sampling strategy, and handling of concentrations below the lower limit of quantification (BLQ) on the outcomes of EE for four population pharmacokinetic models using vancomycin and tobramycin as examples., Methods: Three virtual patient populations undergoing vancomycin or tobramycin therapy were simulated with varying sample size and sampling scenarios. The three approaches used to handle BLQ data were to (1) discard them, (2) impute them as LLOQ/2, or (3) use a likelihood-based approach. EEs were performed with NONMEM and R., Results: Sample size did not have an important impact on the EE results for a given scenario. Increasing the number of samples per patient did not improve predictive performance for two out of the three evaluated models. Evaluating a model developed with rich sampling did not result in better performance than those developed with regular therapeutic drug monitoring. A likelihood-based method to handle BLQ samples impacted the outcomes of the EE with lower bias for predicted troughs., Conclusions: This study suggests that a large sample size may not be necessary for an EE study, and models selected based on TDM may be more generalizable. The study highlights the need for guidelines for EE of population pharmacokinetic models for clinical use., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Therapeutic drug monitoring (TDM) of anti-infectives such as linezolid is routinely performed in blood of intensive care unit (ICU) patients to optimize target attainment. However, the concentration at the site of infection is considered more important for a successful therapy. Until now, bronchoalveolar lavage (BAL) is the gold standard to measure intrapulmonary concentrations of anti-infective agents. However, it is an invasive method and unsuitable for regular TDM. The aim of this proof-of-concept study was to investigate whether it is possible to reliably determine the intrapulmonary concentration of linezolid from endotracheal aspiration (ENTA)., Methods: Intubated ICU patients receiving 600 mg intravenous linezolid twice daily were examined in steady state. First, preliminary experiments were performed in six patients to investigate which patients are suitable for linezolid measurement in ENTA. In a second step, trough and peak linezolid concentrations of plasma and ENTA were determined in nine suitable patients., Results: Linezolid can validly be detected in ENTA with viscous texture and > 0.5 mL volume. The mean (SD) linezolid trough concentration was 2.02 (1.27) mg/L in plasma and 1.60 (1.36) mg/L in ENTA, resulting in a median lung penetration rate of 104%. The mean (SD) peak concentration in plasma and ENTA was 10.77 (5.93) and 4.74 (2.66) mg/L., Conclusions: Linezolid can validly be determined in ENTA with an adequate texture and volume. The penetration rate is comparable to already published BAL concentrations. This method might offer a simple and non-invasive method for TDM at the site of infection "lung". Due to promising results of the feasibility study, comparison of ENTA and BAL in the same patient should be investigated in a further trial., (© 2024. The Author(s).)

Background: The release of toxic bile acids (BAs) in the blood of critically ill patients with cholestatic liver dysfunction might lead to the damage of various organs. Their extracorporeal elimination using the cytokine adsorber Cytosorb ® (CS) (adsorption of especially hydrophobic molecules < 60 kDa) might be promising, but data proving a potential adsorption are missing so far., Methods: The prospective Cyto-SOVLE study (NCT04913298) included 20 intensive care patients with cholestatic liver dysfunction, continuous kidney replacement therapy, total bilirubin concentration > 10 mg/dl and the application of CS into the dialysis circuit. Bilirubin and different BAs were measured pre- and post-CS at defined timepoints (10 min, 1, 3, 6, and 12 h after initiation). Relative reduction (RR, %) was calculated with: [Formula: see text]., Results: The median RR for total and conjugated bilirubin after initiation was - 31.8% and - 30.3%, respectively, and decreased to - 4.5% and - 4.8% after 6 h. A high initial RR was observed for the toxic BAs GCA (- 97.4%), TCA (- 94.9%), GCDCA (- 82.5%), and TCDCA (- 86.0%), decreasing after 6 h to - 32.9%, - 32.7%, - 12.8%, and - 14.3%, respectively. The protective hydrophilic BAs showed a comparable RR after initiation (UDCA: - 77.7%, GUDCA: - 83.0%, TUDCA: - 91.3%) dropping after 6 h to - 7.4%, - 8.5%, and - 12.5%, respectively., Conclusions: Cytosorb ® can adsorb bilirubin and toxic as well as protective BAs. However, a fast saturation of the adsorber resulting in a rapid decrease of the RR was observed. Furthermore, no relevant difference between hydrophobic toxic and hydrophilic protective BAs was detected regarding the adsorption amount. The clinical benefit or harm of the BA adsorption needs to be evaluated in the future., (© 2023. The Author(s).)

Introduction: Hemoadsorption shows promising signals in organ preservation and post lung transplantation. However, its potential impact on the pharmacokinetics of immunosuppressant drugs (ID) is still unknown., Methods: In this interventional study, CytoSorb® hemoperfusion was tested in healthy sheep ( n  = 5) against a sham extracorporeal circuit ( n  = 3). Seven different ID (tacrolimus (TAC), cyclosporin A (CYA), mycophenolate mofetil (MMF), everolimus (EVER), basiliximab (BAS), methylprednisolone (MP) and prednisolone (PRED)) were administered in clinically relevant doses and combinations. Their levels were measured repeatedly in blood samples from the extracorporeal circulation over 6 h following administration. Population pharmacokinetic modeling analysis (NONMEM® 7.5) was performed., Results: Negligible clearance was observed for PRED and BAS. For all other substances, a saturable adsorption sub-model with linear decrease of the adsorption effect over the adsorbed amount best described the measured concentrations. The maximum absolute adsorbed amounts (95% CI) for TAC, CYA, MMF, EVER, and MP were 0.040 (0.028-0.053), 1.15 (0.39-1.91), 4.17 (2.00-6.35), 0.0163 (0.007-0.026), and 53.4 mg (20.9-85.9), respectively, indicating an adsorption of less than 5% of the daily administered dosages for all investigated substances., Discussion: In this large animal model, CytoSorb® hemoperfusion appears to have a limited effect on the clearance of tested ID., Competing Interests: TK and JS are full-time employees of CytoSorbents Europe GmbH. UL has received fees for consulting activities from CytoSorbents Europe GmbH. BL and PS have received research grants from CytoSorbents Europe GmbH. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Leber, Liebchen, Rohrhofer, Weber, Klaus, Scheier, Sucher and Stiegler.)

Purpose: Inadequate piperacillin (PIP) exposure in intensive care unit (ICU) patients threatens therapeutic success. Model-informed precision dosing (MIPD) might be promising to individualize dosing; however, the transferability of published models to external populations is uncertain. This study aimed to externally evaluate the available PIP population pharmacokinetic (PopPK) models., Methods: A multicenter dataset of 561 ICU patients (11 centers/3654 concentrations) was used for the evaluation of 24 identified models. Model performance was investigated for a priori (A) predictions, i.e., considering dosing records and patient characteristics only, and for Bayesian forecasting, i.e., additionally including the first (B1) or first and second (B2) therapeutic drug monitoring (TDM) samples per patient. Median relative prediction error (MPE) [%] and median absolute relative prediction error (MAPE) [%] were calculated to quantify accuracy and precision., Results: The evaluation revealed a large inter-model variability (A: MPE - 135.6-78.3% and MAPE 35.7-135.6%). Integration of TDM data improved all model predictions (B1/B2 relative improvement vs. A: |MPE| median&#95;all&#95;models 45.1/67.5%; MAPE median&#95;all&#95;models 29/39%). The model by Kim et al. was identified to be most appropriate for the total dataset (A/B1/B2: MPE - 9.8/- 5.9/- 0.9%; MAPE 37/27.3/23.7%), Udy et al. performed best in patients receiving intermittent infusion, and Klastrup et al. best predicted patients receiving continuous infusion. Additional evaluations stratified by sex and renal replacement therapy revealed further promising models., Conclusion: The predictive performance of published PIP models in ICU patients varied considerably, highlighting the relevance of appropriate model selection for MIPD. Our differentiated external evaluation identified specific models suitable for clinical use, especially in combination with TDM., (© 2023. The Author(s).)

Cefepime has been reported to cause concentration-related neurotoxicity, especially in critically ill patients with renal failure. This evaluation aimed to identify a dosing regimen providing a sufficient probability of target attainment (PTA) and the lowest justifiable risk of neurotoxicity in critically ill patients. A population pharmacokinetic model was developed based on plasma concentrations over four consecutive days obtained from 14 intensive care unit (ICU) patients. The patients received a median dose of 2,000 mg cefepime by 30-min intravenous infusions with dosing intervals of every 8 h (q8h) to q24h. A time that the free drug concentration exceeds the MIC over the dosing interval ( fT >MIC ) of 65% and an fT >2×MIC of 100% were defined as treatment targets. Monte Carlo simulations were carried out to identify a dosing regimen for a PTA of 90% and a probability of neurotoxicity not exceeding 20%. A two-compartment model with linear elimination best described the data. Estimated creatinine clearance was significantly related to the clearance of cefepime in nondialysis patients. Interoccasion variability on clearance improved the model, reflecting dynamic clearance changes. The evaluations suggested combining thrice-daily administration as an appropriate choice. In patients with normal renal function (creatinine clearance, 120 mL/min), for the pharmacodynamics target of 100% fT >2×MIC and a PTA of 90%, a dose of 1,333 mg q8h was found to be related to a probability of neurotoxicity of ≤20% and to cover MICs up to 2 mg/L. Continuous infusion appears to be superior to other dosing regimens by providing higher efficacy and a low risk of neurotoxicity. The model makes it possible to improve the predicted balance between cefepime efficacy and neurotoxicity in critically ill patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT01793012).

Various studies have reported insufficient beta-lactam concentrations in critically ill patients. The optimal dosing strategy for beta-lactams in critically ill patients, particularly in septic patients, is an ongoing matter of discussion. This retrospective study aimed to evaluate the success of software-guided empiric meropenem dosing (CADDy, Calculator to Approximate Drug-Dosing in Dialysis) with subsequent routine meropenem measurements and expert clinical pharmacological interpretations. Adequate therapeutic drug exposure was defined as concentrations of 8-16 mg/L, whereas concentrations of 16-24 mg/L were defined as moderately high and concentrations >24 mg/L as potentially harmful. A total of 91 patients received meropenem as a continuous infusion (229 serum concentrations), of whom 60% achieved 8-16 mg/L, 23% achieved 16-24 mg/L, and 10% achieved unnecessarily high and potentially harmful meropenem concentrations >24 mg/L in the first 48 h using the dosing software. No patient showed concentrations <2 mg/L using the dosing software in the first 48 h. With a subsequent TDM-guided dose adjustment, therapeutic drug exposure was significantly ( p ≤ 0.05) enhanced to 70%. No patient had meropenem concentrations >24 mg/L with TDM-guided dose adjustments. The combined use of dosing software and consecutive TDM promised a high rate of adequate therapeutic drug exposures of meropenem in patients with sepsis and septic shock.

Vancomycin is a commonly used antibacterial agent in patients with primary central nervous system (CNS) infection. This study aims to examine predictors of vancomycin penetration into cerebrospinal fluid (CSF) in patients with external ventricular drainage and the feasibility of CSF sampling from the distal drainage port for therapeutic drug monitoring. Fourteen adult patients (9 with primary CNS infection) were treated with vancomycin intravenously. The vancomycin concentrations in blood and CSF (from proximal [CSF&#95;P] and distal [CSF&#95;D] drainage ports) were evaluated by population pharmacokinetics. Model-based simulations were conducted to compare various infusion modes. A three-compartment model with first-order elimination best described the vancomycin data. Estimated parameters included clearance (CL, 4.53 L/h), central compartment volume ( V c , 24.0 L), apparent CSF compartment volume ( V CSF , 0.445 L), and clearance between central and CSF compartments ( Q CSF , 0.00322 L/h and 0.00135 L/h for patients with and without primary CNS infection, respectively). Creatinine clearance was a significant covariate on vancomycin CL. CSF protein was the primary covariate to explain the variability of Q CSF . There was no detectable difference between the data for sampling from the proximal and the distal port. Intermittent infusion and continuous infusion with a loading dose reached the CSF target concentration faster than continuous infusion only. All infusion schedules reached similar CSF trough concentrations. Beyond adjusting doses according to renal function, starting treatment with a loading dose in patients with primary CSF infection is recommended. Occasionally, very high and possibly toxic doses would be required to achieve adequate CSF concentrations, which calls for more investigation of direct intraventricular administration of vancomycin. (This study has been registered at ClinicalTrials.gov under registration no. NCT04426383)., Competing Interests: The authors declare no conflict of interest.

The altered pharmacokinetics of renally cleared drugs such as meropenem in critically ill patients receiving continuous renal replacement therapy (CRRT) might impact target attainment. Model-informed precision dosing (MIPD) is applied to individualize meropenem dosing. However, most population pharmacokinetic (PopPK) models developed to date have not yet been evaluated for MIPD. Eight PopPK models based on adult CRRT patients were identified in a systematic literature research and encoded in NONMEM 7.4. A data set of 73 CRRT patients from two different study centers was used to evaluate the predictive performance of the models using simulation and prediction-based diagnostics for i) a priori dosing based on patient characteristics only and ii) Bayesian dosing by including the first measured trough concentration. Median prediction error (MPE) for accuracy within |20%| (95% confidence intervals including zero) and median absolute prediction error (MAPE) for precision ≤ 30% were considered clinically acceptable. For a priori dosing, most models ( n  = 5) showed accuracy and precision MPE within |20%| and MAPE <35%. The integration of the first measured meropenem concentration improved the predictive performance of all models (median MAPE decreased from 35.4 to 25.0%; median MPE decreased from 21.8 to 4.6%). The best predictive performance for intermittent infusion was observed for the O'Jeanson model, including residual diuresis as covariate ( a priori and Bayesian dosing MPE within |2%|, MAPE <30%). Our study revealed the O'Jeanson model as the best-predicting model for intermittent infusion. However, most of the selected PopPK models are suitable for MIPD in CRRT patients when one therapeutic drug monitoring sample is available., Competing Interests: The authors declare no conflict of interest.

Severe rhabdomyolysis frequently results in acute kidney injury (AKI) due to myoglobin accumulation with the need of kidney replacement therapy (KRT). The present study investigated whether the application of Cytosorb® (CS) led to an increased rate of kidney recovery in patients with KRT due to severe rhabdomyolysis. Adult patients with a myoglobin-concentration >10,000 ng/ml and KRT were included from 2014 to 2021. Exclusion criteria were chronic kidney disease and CS-treatment before study inclusion. Groups 1 and 2 were defined as KRT with and without CS, respectively. The primary outcome parameter was independence from KRT after 30 days. Propensity score (PS) matching was performed (predictors: myoglobin, SAPS-II, and age), and the chi 2 -test was used. 35 pairings could be matched (mean age: 57 vs. 56 years; mean myoglobin: 27,218 vs. 26,872 ng/ml; mean SAPS-II: 77 vs. 76). The probability of kidney recovery was significantly ( p  = .04) higher in group 1 (31.4 vs. 11.4%, mean difference: 20.0%, odds ratio (OR): 3.6). Considering patients who survived 30 days, kidney recovery was also significantly ( p  = .03) higher in patients treated with CS (61.1 vs. 23.5%, mean difference: 37.6%, OR: 5.1). In conclusion, the use of CS might positively affect renal recovery in patients with severe rhabdomyolysis. A prospective randomized controlled trial is needed to confirm this hypothesis.

Introduction: Hyperbilirubinemia is often the first evidence for any kind of liver disorder and over one-third of all patients in intensive care units (ICU) show elevated bilirubin concentrations. In critically ill patients, high concentrations of serum bilirubin are correlated with a poor outcome. Therapies to lower bilirubin concentrations are often just symptomatically and their effect on the patients' outcome is hardly evaluated. Therefore, this study investigates whether the extracorporeal elimination of bilirubin with the cytokine adsorber CytoSorb® (CS) reduces mortality in patients with hyperbilirubinemia., Methods: Patients with bilirubin concentrations &gt;10 mg/dL at the ICU were screened for evaluation from 2018 to 2020. Patients with kidney replacement therapy and older than 18 years were included. Patients with continuously decreasing bilirubin concentrations after liver transplantation or other liver support systems (i.e., Molecular Adsorbents Recirculating System [MARS®], Advanced Organ Support [ADVOS]) were excluded. CS therapy was used in clinical routine and was indicated by the treating physicians. Statistical analysis was performed with IBM SPSS statistics utilizing a multivariate model. Primary outcome measure was the effect of CS on the 30-day mortality., Results: Data from 82 patients (mean Simplified Acute Physiology Score [SAPS] II: 74 points, mean bilirubin: 18 mg/dL, mean lactate: 3.7 mmol/L) were analyzed. There were no significant differences in patients with and without CS treatment. The multivariate model showed no significant effect of CS therapy (p = 0.402) on the 30-day mortality. In addition, a significant effect of bilirubin concentration (p = 0.274) or Model for End-Stage Liver Disease score (p = 0.928) on the 30-day mortality could not be shown. In contrast, lactate concentration (p = 0.001, b = 0.044) and SAPS II (p = 0.025, b = 0.008) had significant impact on 30-day mortality., Conclusion: The use of CS in patients with hyperbilirubinemia did not result in a significant reduction in 30-day mortality. Randomized and controlled studies with mortality as primary outcome measure are needed in the future to justify their use., (© 2023 S. Karger AG, Basel.)

Rationale: The concentration-time profile of linezolid varies considerably in critically ill patients. Question of interest is, if the site of infection influences linezolid serum concentrations., Methods: 68 critically ill patients, treated with linezolid, were included. The concentration-time-profile for linezolid was determined using maximum a-posteriori predictions. A trough concentration (C min ) between 2 and 10 mg/L was defined as the target. A generalized linear model (GLM) was established to evaluate potential covariates., Results: The indications for linezolid therapy were in descending order: peritonitis (38.2%), pneumonia (25.0%), infectious acute respiratory distress syndrome (ARDS) (19.1%), and other non-pulmonary infection (17.7%). 27.2 and 7.9% of C min were subtherapeutic and toxic, respectively. In the GLM, ARDS (mean: -2.1 mg/L, CI: -3.0 to -1.2 mg/L) and pneumonia (mean: -2.2 mg/L, CI: -2.8 to -1.6 mg/L) were significant (p < 0.001) determinants of C min . Patients with ARDS (mean: 2.3 mg/L, 51.2% subtherapeutic, 0.0% toxic) and pneumonia (mean: 3.5 mg/L, 41.5% subtherapeutic, 7.7% toxic) had significantly (p < 0.001) lower C min than those with peritonitis (mean: 5.5 mg/L, 14.4% subtherapeutic, 9.3% toxic) and other non-pulmonary infection (mean: 5.2 mg/L, 3.3% subtherapeutic, 16.5% toxic)., Conclusion: Linezolid serum concentrations are reduced in patients with pulmonary infections. Future studies should investigate if other linezolid thresholds are needed in those patients due to linezolid pooling in patients´ lung., Competing Interests: Declaration of Competing Interest Upon manuscript submission, all authors declare they have no competing interests., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Voriconazole (VRC) is used as first line antifungal agent against invasive aspergillosis. Model-based approaches might optimize VRC therapy. This study aimed to investigate the predictive performance of pharmacokinetic models of VRC without pharmacogenetic information for their suitability for model-informed precision dosing. Seven PopPK models were selected from a systematic literature review. A total of 66 measured VRC plasma concentrations from 33 critically ill patients was employed for analysis. The second measurement per patient was used to calculate relative Bias (rBias), mean error (ME), relative root mean squared error (rRMSE) and mean absolute error (MAE) (i) only based on patient characteristics and dosing history (a priori) and (ii) integrating the first measured concentration to predict the second concentration (Bayesian forecasting). The a priori rBias/ME and rRMSE/MAE varied substantially between the models, ranging from -15.4 to 124.6%/-0.70 to 8.01 mg/L and from 89.3 to 139.1%/1.45 to 8.11 mg/L, respectively. The integration of the first TDM sample improved the predictive performance of all models, with the model by Chen (85.0%) showing the best predictive performance (rRMSE: 85.0%; rBias: 4.0%). Our study revealed a certain degree of imprecision for all investigated models, so their sole use is not recommendable. Models with a higher performance would be necessary for clinical use.

Purpose: This case-control study investigated the long-term evolution of multidrug-resistant bacteria (MDRB) over a 5-year period associated with the use of selective oropharyngeal decontamination (SOD) in the intensive care unit (ICU). In addition, effects on health care-associated infections and ICU mortality were analysed., Methods: We investigated patients undergoing mechanical ventilation > 48 h in 11 adult ICUs located at 3 campuses of a university hospital. Administrative, clinical, and microbiological data which were routinely recorded electronically served as the basis. We analysed differences in the rates and incidence densities (ID, cases per 1000 patient-days) of MDRB associated with SOD use in all patients and stratified by patient origin (outpatient or inpatient). After propensity score matching, health-care infections and ICU mortality were compared., Results: 5034 patients were eligible for the study. 1694 patients were not given SOD. There were no differences in the incidence density of MDRB when SOD was used, except for more vancomycin-resistant Enterococcus faecium (0.72/1000 days vs. 0.31/1000 days, p < 0.01), and fewer ESBL-producing Klebsiella pneumoniae (0.22/1000 days vs. 0.56/1000 days, p < 0.01). After propensity score matching, SOD was associated with lower incidence rates of ventilator-associated pneumonia and death in the ICU but not with ICU-acquired bacteremia or urinary tract infection., Conclusions: Comparisons of the ICU-acquired MDRB over a 5-year period revealed no differences in incidence density, except for lower rate of ESBL-producing Klebsiella pneumoniae and higher rate of vancomycin-resistant Enterococcus faecium with SOD. Incidence rates of ventilator-associated pneumonia and death in the ICU were lower in patients receiving SOD., (© 2022. The Author(s).)

Levosimendan is used in severe chronic cardiac insufficiency, also within the peri-operative setting. Real-life pharmacokinetic data in surgical patients is lacking, making therapeutic drug monitoring (TDM) of levosimendan, its pharmacologically active metabolite OR-1896, and its intermediate OR-1855 important. A simultaneous highly sensitive quantification of levosimendan and its metabolites in small-volume samples has not yet been described. Here, levosimendan (LLOQ 0.450 nM), OR-1896, and OR-1855 (LLOQ both 1.0 nM) were successfully quantified by LC-ESI-MS/MS after liquid-liquid extraction in 300 µL of blood. A short C8 column under reversed-phase conditions enabled simultaneous and fast quantification of levosimendan in the negative and the metabolites in the positive ionization mode in a single run within 2 min. Interestingly and unexpectedly, constitutional isomers of levosimendan metabolites with identical mass transitions and similar retention times were observed in surgical patients' samples, which we identified as the metamizole metabolites 4-aminoantipyrine and 4-acetamidoantipyrine. A longer C8 column and a modified mobile phase enabled selective quantification of all analytes in a single run within 7 min. We developed, validated, and applied highly sensitive LC-ESI-MS/MS methods for simultaneous quantification of levosimendan and its metabolites, enabling efficient TDM of cardiac surgery patients even with additional metamizole administration.

Background: Hemadsorption of cytokines is used in critically ill patients with sepsis or septic shock. Concerns have been raised that the cytokine adsorber CytoSorb ® unintentionally adsorbs vancomycin. This study aimed to quantify vancomycin elimination by CytoSorb ® ., Methods: Critically ill patients with sepsis or septic shock receiving continuous renal replacement therapy and CytoSorb ® treatment during a prospective observational study were included in the analysis. Vancomycin pharmacokinetics was characterized using population pharmacokinetic modeling. Adsorption of vancomycin by the CytoSorb ® was investigated as linear or saturable process. The final model was used to derive dosing recommendations based on stochastic simulations., Results: 20 CytoSorb ® treatments in 7 patients (160 serum samples/24 during CytoSorb ® -treatment, all continuous infusion) were included in the study. A classical one-compartment model, including effluent flow rate of the continuous hemodialysis as linear covariate on clearance, best described the measured concentrations (without CytoSorb ® ). Significant adsorption with a linear decrease during CytoSorb ® treatment was identified (p < 0.0001) and revealed a maximum increase in vancomycin clearance of 291% (initially after CytoSorb ® installation) and a maximum adsorption capacity of 572 mg. For a representative patient of our cohort a reduction of the area under the curve (AUC) by 93 mg/L*24 h during CytoSorb ® treatment was observed. The additional administration of 500 mg vancomycin over 2 h during CytoSorb ® attenuated the effect and revealed a negligible reduction of the AUC by 4 mg/L*24 h., Conclusion: We recommend the infusion of 500 mg vancomycin over 2 h during CytoSorb ® treatment to avoid subtherapeutic concentrations. Trial registration NCT03985605. Registered 14 June 2019, https://clinicaltrials.gov/ct2/show/NCT03985605., (© 2022. The Author(s).)

Meropenem is one of the most frequently used antibiotics to treat life-threatening infections in critically ill patients. This study aimed to develop a meropenem dosing algorithm for the treatment of Gram-negative infections based on intensive care unit (ICU)-specific resistance data. Antimicrobial susceptibility testing of Gram-negative bacteria obtained from critically ill patients was carried out from 2016 to 2020 at a tertiary care hospital. Based on the observed MIC distribution, stochastic simulations ( n  = 1,000) of an evaluated pharmacokinetic meropenem model, and a defined pharmacokinetic/pharmacodynamic target (100% T >4×MIC while minimum concentrations were <44.5 mg/L), dosing recommendations for patients with varying renal function were derived. Pathogen-specific MIC distributions were used to calculate the cumulative fraction of response (CFR), and the overall MIC distribution was used to calculate the local pathogen-independent mean fraction of response (LPIFR) for the investigated dosing regimens. A CFR/LPIFR of >90% was considered adequate. The observed MIC distribution significantly differed from the EUCAST database. Based on the 6,520 MIC values included, a three-level dosing algorithm was developed. If the pathogen causing the infection is unknown (level 1), known (level 2), known to be neither Pseudomonas aeruginosa nor Acinetobacter baumannii, or classified as susceptible (level 3), a continuous infusion of 1.5 g daily reached sufficient target attainment independent of renal function. In all other cases, dosing needs to be adjusted based on renal function. ICU-specific susceptibility data should be assessed regularly and integrated into dosing decisions. The presented workflow may serve as a blueprint for other antimicrobial settings.

Beta-lactam dosing is challenging in critically ill patients with slow extended daily dialysis (SLEDD). This prospective observational study aimed to investigate meropenem and piperacillin concentrations and half-lives during SLEDD and in SLEDD-free intervals. Critically ill patients with SLEDD-therapy and meropenem or piperacillin therapy were included. Breakpoints of target attainment were defined as 2 and 20.8 mg/L for meropenem and piperacillin, respectively. Daily TDM was performed and therapies were adapted based on the measured concentrations. Elimination rate constants were determined by using nonlinear regression analysis. Seventeen patients were included (48 SLEDD intervals; median SLEDD-duration: 7.25 h). The median antibiotic trough concentrations and half-lives were significantly (p < 0.001) lower during and after the SLEDD-therapy compared to SLEDD-free intervals (median meropenem: 22.3 (IQR: 12.8, 25.6) vs. 28.3 mg/L (IQR: 16.9, 37.4); median piperacillin: 55.8 (IQR: 45.1, 84.9) vs. 130 mg/L (IQR: 91.5, 154.5); relative change: -48.0% each, IQR meropenem: -33.3, -58.5%; IQR piperacillin: -36.3, -52.1%). However, none of the measured trough concentrations were subtherapeutic during SLEDD. SLEDD leads to a reduction in meropenem and piperacillin concentrations of approximately 50% independently of the initial concentration. If the concentration is twice as high as the breakpoint of target attainment before SLEDD-therapy, subtherapeutic levels can be avoided., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Pneumonia is one of the most common infections in intensive care patients, and it is often treated with beta-lactam antibiotics. Even if therapeutic drug monitoring in blood is available, it is unclear whether sufficient concentrations are reached at the target site: the lung. The present study was initiated to fill this knowledge gap. Various compartments from 10 patients' explanted lungs were subjected to laboratory analysis. Meropenem was quantified in serum, bronchoalveolar lavage (BAL) fluid, microdialysate, and homogenized lung tissue with isotope dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS). BAL fluid represents diluted epithelial lining fluid (ELF), and microdialysate represents interstitial fluid (IF). Differences between target site and blood concentrations were investigated. The median meropenem concentration in blood, ELF, IF, and tissue were 26.8, 18.0, 12.1, and 9.1 mg/liter, respectively. A total of 37.5% of the target site ELF and IF meropenem concentrations were below the clinical EUCAST breakpoint of 8 mg/liter. The median ELF/serum quotient was 61.8% (interquartile range [IQR], 24.8% to 87.6%), the median IF/serum quotient was 35.4% (IQR, 23.8% to 54.3%), and the median tissue/serum quotient was 34.2% (IQR, 28.3% to 38.2%). We observed a substantial interindividual variability between the blood and the compartments (ELF and IF), whereas the intraindividual variability was relatively low. Target site measurement in different lung compartments was feasible and successfully applied in a clinical setting. A relevant amount of 37.5% of the target site concentrations were below the clinical EUCAST breakpoint, indicating subtherapeutic dosing in high-risk patients receiving perioperative antibiotic prophylaxis in lung transplantation. (This study has been registered at ClinicalTrials.gov under identifier NCT03970265.).

The aim of this study was to investigate optimal loading doses prior to continuous infusion of meropenem in critically ill patients. A previously published and successfully evaluated pharmacokinetic model of critically ill patients was used for stochastic simulations of virtual patients. Maintenance doses administered as continuous infusion of 1.5-6 g/24 h with preceding loading doses (administered as 30 min infusion) of 0.15-2 g were investigated. In addition to the examination of the influence of individual covariates, a best-case and worst-case scenario were simulated. Dosing regimens were considered adequate if the 5th percentile of the concentration-time profile did not drop at any time below four times the S/I breakpoint (= 2 mg/L) of Pseudomonas aeruginosa according to the EUCAST definition. Low albumin concentrations, high body weight and high creatinine clearances increased the required loading dose. A maximum loading dose of 0.33 g resulted in sufficient plasma concentrations when only one covariate showed extreme values. If all three covariates showed extreme values (= worst-case scenario), a loading dose of 0.5 g was necessary. Higher loading doses did not lead to further improvements of target attainment. We recommend the administration of a loading dose of 0.5 g meropenem over 30 min immediately followed by continuous infusion., (© 2021. The Author(s).)

Background: Posaconazole and itraconazole are commonly used for systemic antifungal prophylaxis after lung transplantation. The aim of this study on critically ill lung transplant recipients was to assess the rate of adequate plasma concentrations and the frequency of fungal-induced transitions from antifungal prophylaxis to therapy after the administration of either posaconazole or itraconazole for systemic prophylaxis., Methods: Critically ill lung transplant recipients with postoperative posaconazole or itraconazole prophylaxis and therapeutic drug monitoring from February 2016 to November 2019 were retrospectively included in the study. Positive fungal cultures or Aspergillus antigen tests resulting in a transition from antifungal prophylaxis to therapy were analyzed from the first day of prophylaxis until 7 days after the last sample for each patient. Adequate plasma concentrations were defined as ≥500 µg/L for itraconazole and ≥700 µg/L for posaconazole., Results: Two hundred seventy-five samples from 73 patients were included in the analysis. Overall, 60% of the posaconazole and 55% of the itraconazole concentrations were subtherapeutic. Administration of posaconazole suspension resulted significantly (P < .01) more often in subtherapeutic concentrations than tablets (68% vs 10%). Patients treated with posaconazole showed less positive fungal records resulting in a transition from prophylaxis to therapy than patients treated with itraconazole (10% vs 33%, P-value: .029). The detection of a fungal pathogen was not associated with the measured plasma concentrations or the achievement of the target concentrations., Conclusion: Our findings suggest that posaconazole should be used instead of itraconazole for systemic prophylaxis in critically ill lung transplant recipients., (© 2021 The Authors. Transplant Infectious Disease published by Wiley Periodicals LLC.)

Background: A cytokine storm is life threatening for critically ill patients and is mainly caused by sepsis or severe trauma. In combination with supportive therapy, the cytokine adsorber Cytosorb ® (CS) is increasingly used for the treatment of cytokine storm. However, it is questionable whether its use is actually beneficial in these patients., Methods: Patients with an interleukin-6 (IL-6) > 10,000 pg/ml were retrospectively included between October 2014 and May 2020 and were divided into two groups (group 1: CS therapy; group 2: no CS therapy). Inclusion criteria were a regularly measured IL-6 and, for patients allocated to group 1, CS therapy for at least 90 min. A propensity score (PS) matching analysis with significant baseline differences as predictors (Simplified Acute Physiology Score (SAPS) II, extracorporeal membrane oxygenation, renal replacement therapy, IL-6, lactate and norepinephrine demand) was performed to compare both groups (adjustment tolerance: < 0.05; standardization tolerance: < 10%). U-test and Fisher's-test were used for independent variables and the Wilcoxon test was used for dependent variables., Results: In total, 143 patients were included in the initial evaluation (group 1: 38; group 2: 105). Nineteen comparable pairings could be formed (mean initial IL-6: 58,385 vs. 59,812 pg/ml; mean SAPS II: 77 vs. 75). There was a significant reduction in IL-6 in patients with (p < 0.001) and without CS treatment (p = 0.005). However, there was no significant difference (p = 0.708) in the median relative reduction in both groups (89% vs. 80%). Furthermore, there was no significant difference in the relative change in C-reactive protein, lactate, or norepinephrine demand in either group and the in-hospital mortality was similar between groups (73.7%)., Conclusion: Our study showed no difference in IL-6 reduction, hemodynamic stabilization, or mortality in patients with Cytosorb ® treatment compared to a matched patient population., (© 2021. The Author(s).)

Several studies have addressed the poor stability of meropenem in aqueous solutions, though not considering the main degradation product, the open-ring metabolite (ORM) form. In the present work, we elucidate the metabolic fate of meropenem and ORM from continuous infusion to the human bloodstream. We performed in vitro infusate stability tests at ambient temperature with 2% meropenem reconstituted in 0.9% normal saline, and body temperature warmed buffered human serum with 2, 10, and 50 mg/L meropenem, covering the therapeutic range. We also examined meropenem and ORM levels over several days in six critically ill patients receiving continuous infusions. Meropenem exhibited a constant degradation rate of 0.006/h and 0.025/h in normal saline at 22 °C and serum at 37 °C, respectively. Given that 2% meropenem remains stable for 17.5 h in normal saline (≥90% of the initial concentration), we recommend replacement of the infusate every 12 h. Our patients showed inter-individually highly variable, but intra-individually constant molar ORM/(meropenem + ORM) ratios of 0.21-0.52. Applying a population pharmacokinetic approach using the degradation rate in serum, spontaneous degradation accounted for only 6% of the total clearance.

There are different methods of artificial liver support for patients with acute liver dysfunction (ALD). However, CytoSorb (CS) might be a new approved option for those patients. Question of interest is whether the elimination performance of CS was comparable to that of advanced organ support (ADVOS). Patients, treated with CS (integrated into high-flux dialysis) or ADVOS and a total bilirubin > 10 mg/dl were included. Laboratory parameters were evaluated before starting therapy (d0) and 12-24 h thereafter (d1). The Wilcoxon-test with associated samples was used for statistical analysis. Thirty-nine patients (33 CS, 6 ADVOS) were included. The median bilirubin at d0 was 16.9 and 17.7 mg/dl and at d1 was 13.2 and 15.9 mg/dl, in the CS and ADVOS group, respectively. There was a significant bilirubin reduction as well in the CS group (p < 0.001, median relative reduction: 22.5%) as in the ADVOS group (p = 0.028, median relative reduction: 22.8%). There was no significant difference in the relative bilirubin reduction between CS and ADVOS therapies. The use of CytoSorb and ADVOS in patients with ALD led to a significant and comparable decrease in total bilirubin. The easy use of CS might be an advantage compared to other procedures.

Background: The MeroRisk-calculator, an easy-to-use tool to determine the risk of meropenem target non-attainment after standard dosing (1000 mg; q8h), uses a patient's creatinine clearance and the minimum inhibitory concentration (MIC) of the pathogen. In clinical practice, however, the MIC is rarely available. The objectives were to evaluate the MeroRisk-calculator and to extend risk assessment by including general pathogen sensitivity data., Methods: Using a clinical routine dataset (155 patients, 891 samples), a direct data-based evaluation was not feasible. Thus, in step 1, the performance of a pharmacokinetic model was determined for predicting the measured concentrations. In step 2, the PK model was used for a model-based evaluation of the MeroRisk-calculator: risk of target non-attainment was calculated using the PK model and agreement with the MeroRisk-calculator was determined by a visual and statistical (Lin's concordance correlation coefficient (CCC)) analysis for MIC values 0.125-16 mg/L. The MeroRisk-calculator was extended to include risk assessment based on EUCAST-MIC distributions and cumulative-fraction-of-response analysis., Results: Step 1 showed a negligible bias of the PK model to underpredict concentrations (-0.84 mg/L). Step 2 revealed a high level of agreement between risk of target non-attainment predictions for creatinine clearances >50 mL/min (CCC = 0.990), but considerable deviations for patients <50 mL/min. For 27% of EUCAST-listed pathogens the median cumulative-fraction-of-response for the observed patients receiving standard dosing was < 90%., Conclusions: The MeroRisk-calculator was successfully evaluated: For patients with maintained renal function it allows a reliable and user-friendly risk assessment. The integration of pathogen-based risk assessment substantially increases the applicability of the tool.

Background: Galactomannan antigen (GM) testing is widely used in the diagnosis of invasive aspergillosis (IA). Digestive enzymes play an important role in enzyme substitution therapy in exocrine pancreatic insufficiency. As digestive enzymes of fungal origin like Nortase contain enzymes from Aspergillus, a false-positive result of the test might be possible because of cross-reacting antigens of the cell wall of the producing fungi. We, therefore, asked whether the administration of fungal enzymes is a relevant cause of false-positive GM antigen test results., Methods: Patients with a positive GM antigen test between January 2016 and April 2020 were included in the evaluation and divided into two groups: group 1-Nortase-therapy, group 2-no Nortase-therapy. In addition, dissolved Nortase samples were analyzed in vitro for GM and β-1,3-D-glucan. For statistical analysis, the chi-squared and Mann‒Whitney U tests were used., Results: Sixty-five patients were included in this evaluation (30 patients receiving Nortase and 35 patients not receiving Nortase). The overall false positivity rate of GM testing was 43.1%. Notably, false-positive results were detected significantly more often in the Nortase group (73.3%) than in the control group (17.1%, p < 0.001). While the positive predictive value of GM testing was 0.83 in the control group, there was a dramatic decline to 0.27 in the Nortase group. In vitro analysis proved that the Nortase enzyme preparation was highly positive for the fungal antigens GM and β-1,3-D-glucan., Conclusions: Our data demonstrate that the administration of digestive enzymes of fungal origin like Nortase leads to a significantly higher rate of false-positive GM test results compared to that in patients without digestive enzyme treatment.

Background: The present COVID-19 pandemic has prompted worldwide repurposing of drugs. The aim of the present work was to develop and validate a two-dimensional isotope-dilution liquid chromatrography tandem mass spectrometry (ID-LC-MS/MS) method for accurate quantification of remdesivir and its active metabolite GS-441524, chloroquine, hydroxychloroquine, lopinavir, ritonavir, favipiravir and azithromycin in serum; drugs that have gained attention for repurposing in the treatment of COVID-19., Methods: Following protein precipitation, samples were separated with a two-dimensional ultra-high performance liquid chromatography (2D-UHPLC) setup, consisting of an online solid phase extraction (SPE) coupled to an analytical column. For quantification, stable isotope-labelled analogues were used as internal standards for all analytes. The method was validated on the basis of the European Medicines Agency bioanalytical method validation protocol., Results: Detuning of lopinavir and ritonavir allowed simultaneous quantification of all analytes with different concentration ranges and sensitivity with a uniform injection volume of 5 μL. The method provided robust validation results with inaccuracy and imprecision values of ≤ 9.59 % and ≤ 11.1 % for all quality controls., Conclusion: The presented method is suitable for accurate and simultaneous quantification of remdesivir, its metabolite GS-441525, chloroquine, hydroxychloroquine, lopinavir, ritonavir, favipiravir and azithromycin in human serum. The quantitative assay may be an efficient tool for the therapeutic drug monitoring of these potential drug candidates in COVID-19 patients in order to increase treatment efficacy and safety., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to declare., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Rhabdomyolysis is frequently occurring in critically ill patients, resulting in a high risk of acute kidney injury (AKI) and potentially permanent kidney damage due to increased myoglobin levels. The extracorporeal elimination of myoglobin might be an approach to prevent AKI, but its molecular weight of 17 kDa complicates an elimination with conventional dialysis membranes. Question of interest is, if myoglobin can be successfully eliminated with the cytokine adsorber Cytosorb® (CS) integrated in a high-flux dialysis system., Methods: Patients were included between 10/2014 and 05/2020 in the study population if they had an anuric renal failure with the need of renal replacement therapy, if CS therapy was longer than 90 min and if myoglobin level was > 5.000 ng/ml before treatment. The measurement times of the laboratory values were: d-1 = 24-36 h before CS, d0 = shortly before starting CS and d1 = 12-24 h after starting CS treatment. Statistical analysis were performed with Spearman's correlation coefficient, Wilcoxon test with associated samples and linear regression analysis., Results: Forty-three patients were included in the evaluation (median age: 56 years, 77% male patients, 32.6% ECMO therapy, median SAPS II: 80 points and in-hospital mortality: 67%). There was a significant equilateral correlation between creatine kinase (CK) and myoglobin at all measurement points. Furthermore, there was a significant reduction of myoglobin (p = 0.03, 95% confidence interval (CI): - 9030, - 908 ng/ml) during CS treatment, with a median relative reduction of 29%. A higher median reduction of 38% was seen in patients without ongoing rhabdomyolysis (CK decreased during CS treatment, n = 21). In contrast, myoglobin levels did not relevantly change in patients with increasing CK and therefore ongoing rhabdomyolysis (n = 22, median relative reduction 4%). Moreover, there was no significant difference in myoglobin elimination in patients with and without ECMO therapy., Conclusion: Blood purification with Cytosorb® during high-flux dialysis led to a significant reduction of myoglobin in patients with severe rhabdomyolysis. The effect might be obscured by sustained rhabdomyolysis, which was seen in patients with rising CK during treatment. Prospective clinical trials would be useful in investigating its benefits in avoiding permanent kidney damage.

Objectives: Beta-lactam antibiotics are often subject to therapeutic drug monitoring, but breakpoints of target attainment are mostly based on expert opinions. Studies that show a correlation between target attainment and infection resolution are missing. This analysis investigated whether there is a difference in infection resolution based on two breakpoints of target attainment., Methods: An outcome group out of 1392 critically ill patients treated with meropenem or piperacillin-tazobactam was formed due to different selection criteria. Afterwards, three groups were created: group 1=free drug concentration (f) was < 100% of the time (T) above the minimal inhibitory concentration (MIC) (< 100% fT > MIC ), group 2=100% fT > MIC < 4xMIC , and group 3=100% fT > 4xMIC . Parameters for infection control, renal and liver function, and estimated and observed in-hospital mortality were compared between those groups. Statistical analysis was performed with one-way analysis of variance, Tukey post hoc test, U test, and bivariate logistic regression., Results: The outcome group consisted of 55 patients (groups 1-3, 17, 24, and 14 patients, respectively). Patients allocated to group 2 or 3 had a significantly faster reduction of the C-reactive protein in contrast to patients allocated to group 1 (p = 0.033 and p = 0.026). Patients allocated to group 3 had a worse renal function, a higher Acute Physiology and Chronic Health Evaluation (APACHE II) score, were older, and had a significantly higher in-hospital mortality compared to group 1 (p = 0.017) and group 2 (p = 0.001). The higher mortality was significantly influenced by worse liver function, higher APACHE II, and higher Sequential Organ Failure Assessment (SOFA) score and norepinephrine therapy., Conclusion: Achieving the target 100% fT > MIC leads to faster infection resolution in the critically ill. However, there was no benefit for patients who reached the highest target of 100% fT > 4xMIC , although the mortality rate was higher possibly due to confounding effects. In conclusion, we recommend the target 100% fT > MIC < 4xMIC for critically ill patients., Trial Registration: NCT03985605.

Various studies have reported insufficient beta-lactam concentrations in critically ill patients. The extent to which therapeutic drug monitoring (TDM) in clinical practice can reduce insufficient antibiotic concentrations is an ongoing matter of investigation. We retrospectively evaluated routine meropenem and piperacillin measurements in critically ill patients who received antibiotics as short infusions in the first year after initiating a beta-lactam TDM program. Total trough concentrations above 8.0 mg/L for meropenem and above 22.5 mg/L for piperacillin were defined as the breakpoints for target attainment. We included 1832 meropenem samples and 636 piperacillin samples. We found that 39.3% of meropenem and 33.6% of piperacillin samples did not reach the target concentrations. We observed a clear correlation between renal function and antibiotic concentration (meropenem, r = 0.53; piperacillin, r = 0.63). Patients with renal replacement therapy or creatinine clearance (CrCl) of <70 mL/min had high rates of target attainment with the standard dosing regimens. There was a low number of patients with a CrCl >100 mL/min that achieved the target concentrations with the maximum recommended dosage. Patients with impaired renal function only required TDM if toxic side effects were noted. In contrast, patients with normal renal function required different dosage regimens and TDM-guided therapy to reach the breakpoints of target attainment.

Background: Therapeutic drug monitoring (TDM) of beta-lactam antibiotics has become a valuable tool to guide dosing in critically ill patients. The main goal of the study was to compare two routinely used techniques for beta-lactam TDM in intensive care unit (ICU) patient samples, namely isotope dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS) and high-performance liquid chromatography combined with ultra-violet detection (HPLC-UV)., Methods: A set of 80 sera/plasma samples from ICU patients receiving therapeutic meropenem or piperacillin dosage was investigated. Sample duplicates and quality assessment samples were assayed in parallel with an in-house LC-MS/MS and a commercially available IVD HPLC-UV kit. A pharmacokinetic and pharmacodynamic (PK/PD) target with ≥ 22.5 mg/L for piperacillin and ≥ 8.0 mg/L for meropenem was used for medical assessment of trough sample (n = 40) antibiotic concentrations., Results: There was no difference between serum and Li-heparin plasmas. Concentration deviations were found for 4% of meropenem and 17% of piperacillin samples. Eliminating the influence of the systemic bias of approximately 10% for piperacillin, measurement discrepancies ≥ 25% between LC-MS/MS and HPLC-UV analyses were only observed for ≈ 4 - 6% of all samples. In the same way, identical PK/PD target attainment rates of 50 - 60% could be obtained., Conclusions: After correction of the analytical bias for piperacillin measurements, both methods showed comparable results, also with respect to clinical decision limits. HPLC-UV analysis is an adequate TDM methodology for testing of beta-lactam antibiotics in centers where no special knowledge in LC-MS/MS based TDM is present. However, potential matrix effects, interferences, and calibration issues for both methods must be taken into account.

Introduction: The aim of this project was to develop and validate an isotope-dilution liquid chromatography high resolution mass spectrometry (LC-HRMS) method for the quantification of the 11 most widely used systemic antimycotics and to study whether HRMS is a feasible alternative for therapeutic drug monitoring (TDM) when compared to tandem MS (MS/MS) technology., Methods: After protein precipitation, followed by automated online sample clean-up the analytes were separated within 4 min on a C18 column using an acetonitrile-water gradient. Eleven antimycotics, namely 5-flucytosine, amphotericin B, anidulafungin, fluconazole, isavuconazole, itraconazole, ketoconazole, micafungin, OH-itraconazole, posaconazole and voriconazole were finally quantified in full MS scan mode using positive electrospray ionization (ESI +) with a mass range fromm/z 110-1300 using HRMS. The method was comprehensively validated on the basis of the European Medicines Agengy (EMA) method validation protocol using commercially available IVD kit components., Results: Good linear relationship between peak area responses and drug concentrations (R 2 > 0.995) and excellent selectivity were observed for all antimycotics in this study. Inaccuracy and imprecision of all quality controls were consistently below ± 12.6% and ± 8.1%, respectively. Quantification results were in agreement with an IVD LC-MS/MS method., Conclusion: HRMS was shown to be suitable for TDM of small molecules when compared to tandem mass spectrometry. The novel HRMS method is quickly installed and may be a robust and reliable tool for routine TDM of antimycotics in clinical laboratories., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Tigecycline, a tetracycline derivative, shows atypical plasma protein binding behavior. The unbound fraction decreases with increasing concentration at therapeutic concentrations. Moreover, uncertainty exists about the magnitude of tigecyline's protein binding in man. Unbound fractions between 2.5% and 35% have been reported in plasma from healthy volunteers, and between 25% and 100% in patients, respectively. In the present study, the protein binding of tigecycline has been investigated by ultrafiltration using different experimental conditions. Whereas temperature had only a marginal influence, the unbound fraction at 0.3/3.0 mg/L was low at pH 8.2 (9.4%/1.9%) or in unbuffered pooled plasma (6.3%/1.2%), compared with plasma buffered with HEPES to pH 7.4 (65.9%/39.7%). In experiments with phosphate buffer and EDTA, the concentration dependency was markedly attenuated or abolished, which is compatible with a cooperative binding mechanism involving divalent cations such as calcium. The unbound fraction in clinical plasma samples from patients treated with tigecycline was determined to 66.3 ± 13.7% at concentrations <0.3 mg/L compared with 41.3 ± 16.0% at >1 to <5 mg/L. To summarize, tigecycline appears to be only moderately bound to plasma proteins as determined by ultrafiltration, when a physiological pH is maintained., (Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Background: Standard doses of linezolid may not be suitable for all patient groups. Intensive care unit (ICU) patients in particular may be at risk of inadequate concentrations. This study investigated variability of drug exposure and its potential sources in this population., Methods: Plasma concentrations of linezolid were determined by high-performance liquid chromatography in a convenience sample of 20 ICU patients treated with intravenous linezolid 600 mg twice daily. Ultrafiltration applying physiological conditions (pH 7.4/37°C) was used to determine the unbound fraction. Individual pharmacokinetic (PK) parameters were estimated by population PK modeling. As measures of exposure to linezolid, area under the concentration-time curve (AUC) and trough concentrations (Cmin) were calculated and compared with published therapeutic ranges (AUC 200-400 mg*h/L, Cmin 2-10 mg/L). Coadministered inhibitors or inducers of cytochrome P450 and/or P-glycoprotein were noted., Results: Data from 18 patients were included into the PK evaluation. Drug exposure was highly variable (median, range: AUC 185, 48-618 mg*h/L, calculated Cmin 2.92, 0.0062-18.9 mg/L), and only a minority of patients had values within the target ranges (6 and 7, respectively). AUC and Cmin were linearly correlated (R = 0.98), and classification of patients (underexposed/within therapeutic range/overexposed) according to AUC or Cmin was concordant in 15 cases. Coadministration of inhibitors was associated with a trend to higher drug exposure, whereas 3 patients treated with levothyroxine showed exceedingly low drug exposure (AUC ∼60 mg*h/L, Cmin <0.4 mg/L). The median unbound fraction in all 20 patients was 90.9%., Conclusions: Drug exposure after standard doses of linezolid is highly variable and difficult to predict in ICU patients, and therapeutic drug monitoring seems advisable. PK drug-drug interactions might partly be responsible and should be further investigated; protein binding appears to be stable and irrelevant.