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Objective: The pharmacokinetics of mycophenolic acid (MPA) were compared in renal transplant patients receiving either mycophenolate mofetil (MMF) or enteric-coated mycophenolate sodium (EC-MPS).Methods: MPA concentration-time profiles were included from EC-MPS- (n = 208) and MMF-treated (n = 184) patients 4-257 months after renal transplantation. Population pharmacokinetic analysis was performed using nonlinear mixed-effects modelling (NONMEM). A two-compartment model with first-order absorption and elimination was used to describe the data.Results: No differences were detected in MPA clearance, intercompartmental clearance, or the central or peripheral volume of distribution. Respective values and interindividual variability (IIV) were 16 L/h (39%), 22 L/h (78%), 40 L (100%) and 518 L (490%). EC-MPS was absorbed more slowly than MMF with respective absorption rate constant values of 3.0 h(-1) and 4.1 h(-1) (p < 0.001) [IIV 187%]. A mixture model was used for the change-point parameter lag-time (t(lag)) in order to describe IIV in this parameter adequately for EC-MPS. Following the morning dose of EC-MPS, the t(lag) values were 0.95, 1.88 and 4.83 h for 51%, 32% and 17% of the population (IIV 8%), respectively. The morning t(lag) following EC-MPS administration was significantly different from both the t(lag) following MMF administration (0.30 h; p < 0.001 [IIV 11%]) and the t(lag) following the evening dose of EC-MPS (9.04 h; p < 0.001 [IIV 40%]). Post hoc analysis showed that the t(lag) was longer and more variable following EC-MPS administration (morning median 2.0 h [0.9-5.5 h], evening median 8.9 h [5.4-12.3 h]) than following MMF administration (median 0.30 h [0.26-0.34 h]; p < 0.001). The morning MPA predose concentrations were higher and more variable following EC-MPS administration than following MMF administration, with respective values of 2.6 mg/L (0.4-24.4 mg/L) and 1.6 mg/L (0.2-7.6 mg/L). The correlation between predose concentrations and the area under the plasma concentration-time curve (AUC) was lower in EC-MPS-treated patients (r(2) = 0.02) than in MMF-treated patients (r(2) = 0.48).Conclusion: Absorption of MPA was delayed and also slower following EC-MPS administration than following MMF administration. Furthermore, the t(lag) varied more in EC-MPS-treated patients. MPA predose concentrations were poorly correlated with the MPA AUC in both MMF- and EC-MPS-treated patients. [ABSTRACT FROM AUTHOR]

Objectives: Patients with liver cirrhosis are prone to develop severe bacterial infections. Pharmacokinetics (PK) of antibiotics in cirrhosis are potentially affected by impaired biotransformation phases 0-3 and consequences of portal hypertension such as portovenous shunting, ascites formation and/or acute kidney injury (AKI). We aimed to elucidate to what extent PK of selected antibiotics and, therefore, dosage recommendations are affected in adults with cirrhosis., Methods: We performed a systematic search in PubMed, Embase, Cochrane and CINAHL on effects of cirrhosis on PK profiles of ceftriaxone, fosfomycin, gentamicin, meropenem, nitrofurantoin, piperacillin/tazobactam and vancomycin in adults. Antibiotics were selected based on the lack of specific dosing recommendations for adults with cirrhosis. We included studies reporting on ≥1 of the following PK parameters: AUC, half-life (t½), CL, volume of distribution (Vd), peak (Cmax) or trough concentrations (Cmin)., Results: We identified 15 studies (ceftriaxone, n = 5; gentamicin, n = 3; meropenem n = 5; vancomycin, n = 2), including 379 patients with cirrhosis, of which two were of high quality. No eligible studies were identified for fosfomycin, nitrofurantoin or piperacillin/tazobactam. Ceftriaxone unbound concentration increased in cirrhosis, but was mitigated by increased renal CL. Gentamicin levels in ascitic fluid were comparable to those in plasma. Meropenem PK parameters were not altered in cirrhosis without AKI, but in the presence of AKI a decrease in CL was observed. In contrast, vancomycin CL decreased in advanced cirrhosis., Conclusions: Available data in studies of mostly moderate quality suggest that PK of ceftriaxone, meropenem and vancomycin are altered in cirrhosis. More advanced PK studies are needed to provide specific dosing recommendations., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy.)

Background: Many trials, reviews, and meta-analyses have been performed on the comparison of short versus long antibiotic treatment in respiratory tract infections, generally supporting shorter treatment. The aim of this umbrella review is to assess the soundness of the current evidence base for optimal antibiotic treatment duration., Methods: A search in Ovid MEDLINE, Embase, and Clarivate Analytics Web of Science Core Collection was performed on May 1, 2024, without date and language restrictions. Systematic reviews addressing treatment durations in community-acquired pneumonia (CAP), acute exacerbation of chronic obstructive pulmonary disease (AECOPD), hospital-acquired pneumonia (HAP), acute sinusitis, and streptococcal pharyngitis, tonsillitis, or pharyngotonsillitis were included. Studies from inpatient and outpatient settings were included; reviews in paediatric populations were excluded. Outcomes of interest were clinical and bacteriological cure, microbiological eradication, mortality, relapse rate, and adverse events. The quality of the reviews was assessed using the AMSTAR 2 tool, risk of bias of all included randomised controlled trials (RCTs) using the Cochrane risk-of-bias tool (version 1), and overall quality of evidence according to GRADE., Findings: We identified 30 systematic reviews meeting the criteria; they were generally of a low to critically low quality. 21 reviews conducted a meta-analysis. For CAP outside the intensive care unit (ICU; 14 reviews, of which eight did a meta-analysis) and AECOPD (eight reviews, of which five did a meta-analysis), there was sufficient evidence supporting a treatment duration of 5 days; evidence for shorter durations is scarce. Evidence on non-ventilator-associated HAP is absent, despite identifying three reviews (of which one did a meta-analysis), since no trials were conducted exclusively in this population. For sinusitis the evidence appears to support a shorter regimen, but more evidence is needed in the population who actually require antibiotic treatment. For pharyngotonsillitis (eight reviews, of which six did a meta-analysis), sufficient evidence exists to support short-course cephalosporin but not short-course penicillin when dosed three times a day., Interpretation: The available evidence for non-ICU CAP and AECOPD supports a short-course treatment duration of 5 days in patients who have clinically improved. Efforts of the scientific community should be directed at implementing this evidence in daily practice. High-quality RCTs are needed to underpin even shorter treatment durations for CAP and AECOPD, to establish the optimal treatment duration of HAP and acute sinusitis, and to evaluate shorter duration using an optimal penicillin dosing schedule in patients with pharyngotonsillitis., Funding: None., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)

Recent studies have explored the influence of obesity and critical illness on ciprofloxacin pharmacokinetics. However, variation across the subpopulation of individuals with obesity admitted to the intensive care unit (ICU) with varying renal function remains unexamined. This study aims to characterize ciprofloxacin pharmacokinetics in ICU patients with obesity and provide dose recommendations for this special population. Individual patient data of 34 ICU patients with obesity (BMI >30 kg/m 2 ) from four studies evaluating ciprofloxacin pharmacokinetics in ICU patients were pooled and combined with data from a study involving 10 individuals with obesity undergoing bariatric surgery. All samples were collected after intravenous administration. Non-linear mixed effects modeling and simulation were used to develop a population pharmacokinetic model and describe ciprofloxacin exposure in plasma. Model-based dose evaluations were performed using a pharmacokinetic/pharmacodynamic target of AUC/MIC >125. The data from patients with BMI ranging from 30.2 to 58.1 were best described by a two-compartment model with first-order elimination and a proportional error model. The inclusion of Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) as a covariate on clearance reduced inter-individual variability from 57.3% to 38.5% (P < .001). Neither body weight nor ICU admission significantly influenced clearance or volume of distribution. Renal function is a viable predictor for ciprofloxacin clearance in ICU patients with obesity, while critical illness and body weight do not significantly alter clearance. As such, body weight and critical illness do not need to be accounted for when dosing ciprofloxacin in ICU patients with obesity. Individuals with CKD-EPI >60 mL/min/1.73 m 2 may require higher dosages for the treatment of pathogens with minimal inhibitory concentration ≥0.25 mg/L., (© 2024 The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Aims: Little is known about the population pharmacokinetics (PPK) of vancomycin in neonates with perinatal asphyxia treated with therapeutic hypothermia (TH). We aimed to describe the PPK of vancomycin and propose an initial dosing regimen for the first 48 h of treatment with pharmacokinetic/pharmacodynamic target attainment., Methods: Neonates with perinatal asphyxia treated with TH were included from birth until Day 6 in a multicentre prospective cohort study. A vancomycin PPK model was constructed using nonlinear mixed-effects modelling. The model was used to evaluate published dosing guidelines with regard to pharmacokinetic/pharmacodynamic target attainment. The area under the curve/minimal inhibitory concentration ratio of 400-600 mg*h/L was used as target range., Results: Sixteen patients received vancomycin (median gestational age: 41 [range: 38-42] weeks, postnatal age: 4.4 [2.5-5.5] days, birth weight: 3.5 [2.3-4.7] kg), and 112 vancomycin plasma concentrations were available. Most samples (79%) were collected during the rewarming and normothermic phase, as vancomycin was rarely initiated during the hypothermic phase due to its nonempirical use. An allometrically scaled 1-compartment model showed the best fit. Vancomycin clearance was 0.17 L/h, lower than literature values for term neonates of 3.5 kg without perinatal asphyxia (range: 0.20-0.32 L/h). Volume of distribution was similar. Published dosing regimens led to overexposure within 24 h of treatment. A loading dose of 10 mg/kg followed by 24 mg/kg/day in 4 doses resulted in target attainment., Conclusion: Results of this study suggest that vancomycin clearance is reduced in term neonates with perinatal asphyxia treated with TH. Lower dosing regimens should be considered followed by model-informed precision dosing., (© 2024 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Background: Avoiding excessive antibiotic treatment duration is a fundamental goal in antimicrobial stewardship. Manual collection of data is a time-consuming process, but a semi-automated approach for data extraction has been shown feasible for community-acquired infections (CAI). Extraction of data however may be more challenging in hospital-acquired infections (HAI). The aim of this study is to explore whether semi-automated data extraction of treatment duration is also feasible and accurate for HAI., Methods: Data from a university-affiliated hospital over the period 1-6-2020 until 1-6-2022 was used for this study. From the Electronic Health Record, raw data on prescriptions, registered indications and admissions was extracted and processed to define treatment courses. In addition, clinical notes including prescription instructions were obtained for the purpose of validation. The derived treatment course was compared to the registered indication and the actual length of treatment (LOT) in the clinical notes in a random sample of 5.7% of treatment courses, to assess the accuracy of the data for both CAI and HAI., Results: Included were 10.564 treatment courses of which 73.1% were CAI and 26.8% HAI. The registered indication matched the diagnosis as recorded in the clinical notes in 79% of treatment courses (79.2% CAI, 78.5% HAI). Higher error rates were seen in urinary tract infections (UTIs) (29.0%) and respiratory tract infections (RTIs) (20.5%) compared to intra-abdominal infections (7.4%), or skin or soft tissue infections (11.1%), mainly due to incorrect specification of the type of UTI or RTI. The LOT was accurately extracted in 98.5% of courses (CAI 98.2%, HAI 99.3%) when compared to prescriptions in the EHR. In 21% of cases however the LOT did not match with the clinical notes, mainly if patients received treatment from other health care providers preceding or following the present course., Conclusion: Semi-automatic data extraction can yield reliable information about the indication and LOT in treatment courses of hospitalized patients, for both HAI and CAI. This can provide stewardship programs with a surveillance tool for all in-hospital treated infections, which can be used to achieve stewardship goals., (© 2024. The Author(s).)

Background: Desmopressin is frequently used perioperatively in persons with nonsevere hemophilia A. However, increase in factor (F)VIII:C after desmopressin use is interindividually highly variable. Tachyphylaxis has only been reported in test setting for persons with hemophilia A, with a remaining response of approximately 70% after a second dose compared with that after a first dose., Objectives: To study tachyphylaxis of FVIII:C response after multiple administration(s) of desmopressin in perioperative persons with nonsevere hemophilia A., Methods: We studied FVIII:C levels after desmopressin before (day 0 [D0]) and on days 1 (D1) and 2 (D2) after surgery in 26 patients of the DAVID and Little DAVID studies. We studied tachyphylaxis by comparing the responses at D1 and D2 with that at D0. We also assessed the reproducibility of the D0 response in comparison to an earlier performed desmopressin test., Results: The median absolute FVIII:C increase was 0.50 IU/mL (0.35-0.74; n  = 23) at D0, 0.21 IU/mL (0.14-0.28; n  = 17) at D1, and 0.23 IU/mL (0.16-0.30; n  = 11) at D2. The median percentage of FVIII increase after the second administration (D1) compared with the first (D0) was 42.9% (29.2%-52.5%; n  = 17) and that of the third (D2) compared with the first (D0) was 36.4% (23.7%-46.9%; n  = 11). The FVIII:C desmopressin response at D0 was comparable with the desmopressin test response in 74% of the patients., Conclusion: Tachyphylaxis in the surgical setting was considerably more pronounced than previously reported, with FVIII:C at D1 and D2 of 36% to 43% of the initial response. Our results may have important implications for monitoring repeated desmopressin treatment when used perioperatively., (© 2024 The Authors.)

Introduction: Non-severe haemophilia A patient can be treated with desmopressin or factor VIII (FVIII) concentrate. Combining both may reduce factor consumption, but its feasibility and safety has never been investigated., Aim: We assessed the feasibility and safety of combination treatment in nonsevere haemophilia A patients., Methods: Non-severe, desmopressin responsive, haemophilia A patients were included in one of two studies investigating peri-operative combination treatment. In the single-arm DAVID study intravenous desmopressin (0.3 μg/kg) once-a-day was, after sampling, immediately followed by PK-guided FVIII concentrate, for maximally three consecutive days. The Little DAVID study was a randomized trial in patients undergoing a minor medical procedure, whom received either PK-guided combination treatment (intervention arm) or PK-guided FVIII concentrate only (standard arm) up to 2 days. Dose predictions were considered accurate if the absolute difference between predicted and measured FVIII:C was ≤0.2 IU/mL., Results: In total 32 patients (33 procedures) were included. In the DAVID study (n = 21), of the FVIII:C trough levels 73.7% (14/19) were predicted accurately on day 1 (D1), 76.5% (13/17) on D2. On D0, 61.9% (13/21) of peak FVIII:C levels predictions were accurate. In the Little DAVID study (n = 12), on D0 83.3% (5/6) FVIII:C peak levels for both study arms were predicted accurately. Combination treatment reduced preoperative FVIII concentrate use by 47% versus FVIII monotherapy. Desmopressin side effects were mild and transient. Two bleeds occurred, both despite FVIII:C > 1.00 IU/mL., Conclusion: Peri-operative combination treatment with desmopressin and PK-guided FVIII concentrate dosing in nonsevere haemophilia A is feasible, safe and reduces FVIII consumption., (© 2024 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

In the intensive care unit (ICU), infection-related mortality is high. Although adequate antibiotic treatment is essential in infections, beta-lactam target non-attainment occurs in up to 45% of ICU patients, which is associated with a lower likelihood of clinical success. To optimize antibiotic treatment, we aimed to develop beta-lactam target non-attainment prediction models in ICU patients. Patients from two multicenter studies were included, with intravenous intermittent beta-lactam antibiotics administered and blood samples drawn within 12-36 h after antibiotic initiation. Beta-lactam target non-attainment models were developed and validated using random forest (RF), logistic regression (LR), and naïve Bayes (NB) models from 376 patients. External validation was performed on 150 ICU patients. We assessed performance by measuring discrimination, calibration, and net benefit at the default threshold probability of 0.20. Age, sex, serum creatinine, and type of beta-lactam antibiotic were found to be predictive of beta-lactam target non-attainment. In the external validation, the RF, LR, and NB models confirmed good discrimination with an area under the curve of 0.79 [95% CI 0.72-0.86], 0.80 [95% CI 0.73-0.87], and 0.75 [95% CI 0.67-0.82], respectively, and net benefit in the RF and LR models. We developed prediction models for beta-lactam target non-attainment within 12-36 h after antibiotic initiation in ICU patients. These online-accessible models use readily available patient variables and help optimize antibiotic treatment. The RF and LR models showed the best performance among the three models tested.

Aims: Pharmacokinetic/pharmacodynamic target attainment of ceftriaxone is compromised in intensive care unit (ICU) patients and non-ICU hospitalized patients in Beira, Mozambique. Whether this also accounts for non-ICU patients in a high-income setting is unknown. We therefore assessed the probability of target attainment (PTA) of the currently recommended dosing regimen of 2 g every 24 h (q24h) in this patient group., Methods: We performed a multicentre population pharmacokinetic study in hospitalized non-ICU adult patients empirically treated with intravenous ceftriaxone. During both the acute phase of infection (i.e. first 24 h of treatment) and convalescence, a maximum of 4 random blood samples were obtained per patient for ceftriaxone total and unbound concentration measurements. PTA was calculated using NONMEM and was defined as the percentage of patients of which the unbound ceftriaxone concentration exceeded the minimum inhibitory concentration (MIC) for >50% of the first dosing interval of 24 h. Monte Carlo simulations were performed to determine PTA for different estimated glomerular filtration rates (eGFR; CKD-EPI) and MICs. PTA >90% was considered adequate., Results: Forty-one patients provided 252 ceftriaxone total and 253 unbound concentrations. The median eGFR was 65 mL/min/1.73 m 2 (5th to 95th percentile 36-122). With the recommended dose of 2 g q24h, PTA >90% was achieved for bacteria with an MIC ≤2 mg/L. Simulations showed that PTA was insufficient for an MIC of 4 mg/L in case the eGFR was 122 mL/min/1.73 m 2 (PTA 56.9%) and for an MIC of 8 mg/L regardless of eGFR., Conclusion: The PTA of 2 g q24h ceftriaxone dosing is adequate for common pathogens during the acute phase of infection in non-ICU patients., (© 2023 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Abstract: This grand round describes the case of a patient who received 10 grams (143.5 mg/kg) of vancomycin every 24 hours via continuous infusion, in whom the highest observed level was only 15.4 mg/L. Despite subtherapeutic levels, renal impairment was encountered, which resolved after the discontinuation of vancomycin. Glomerular hyperfiltration was found through nuclear glomerular filtration rate measurement, which likely explains the need for high doses (>6 grams per 24 hours continuous infusion) without reaching therapeutic serum levels., Competing Interests: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

According to current guidelines, atovaquone-proguanil (AP) malaria chemoprophylaxis should be taken once daily starting one day before travel and continued for seven days post-exposure. However, drug-sparing regimens, including discontinuing AP after leaving malaria-endemic areas are cost-saving and probably more attractive to travelers, and may thus enhance adherence. AP has causal prophylactic effects, killing malaria parasites during the hepatic stage. If early hepatic stages were already targeted by AP, AP could possibly be discontinued upon return. Pharmacokinetic data and studies on drug-sparing AP regimens suggest this to be the case. Nevertheless, the evidence is weak and considered insufficient to modify current recommendations. Field trials require large numbers of travelers and inherently suffer from the lack of a control group. Safely-designed controlled human malaria infection trials could significantly reduce study participant numbers and safely establish an effective AP abbreviated regimen which we propose as the optimal trial design to test this concept., Competing Interests: Declaration of competing interest All authors report no potential conflicts of interests., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

No prospective evidence exists on the pharmacokinetic/pharmacodynamic (PK/PD) target attainment of ceftazidime in adult patients on general wards. We aimed to investigate whether the PK/PD target of ceftazidime (50% T > MIC) is attained in adult patients on general wards with adequate and impaired renal function receiving regular and guideline-recommended reduced doses of ceftazidime. In this observational, prospective, bicenter cohort study, adult patients admitted to a general ward receiving ceftazidime as part of standard care were included. Three blood samples per patient within 72 h after start of treatment were collected. Data were analyzed with nonlinear mixed effects modeling. The primary endpoint was target attainment of 50% T > MIC during the first 24 h of treatment (50% T 0-24 > MIC). Forty patients were included from whom 121 blood samples were obtained. All 25/25 patients with adequate renal function, 9/10 patients with moderately impaired renal function (eGFR 30-50 mL/min/1.73 m 2 ) and 5/5 patients with severe impaired renal function (eGFR < 30 mL/min/1.73 m 2 ) attained 50% T 0-24 > MIC when applying the clinical breakpoint MIC for Pseudomonas aeruginosa of 8 mg/L. The one patient not attaining the PK/PD target did not differ in any of the collected patients' characteristics, except that this patient was the oldest in the study population. However, age was not statistically significantly associated with clearance or volume of distribution in the population pharmacokinetic model and, therefore, not likely the cause for this patient not attaining the PK/PD target. Our results suggest ≥90% probability of the PK/PD target attainment of ceftazidime in patients on general wards with adequate and impaired renal function receiving regular and guideline-recommended reduced doses of ceftazidime for treatment of infections with Pseudomonas aeruginosa and all bacteria with lower MIC-values.

Objectives: During the acute phase of infection, IV antibiotics are preferred to ensure adequate systemic exposure. To assess whether adequate exposure may also be achieved with oral antibiotics, we investigated exposure to oral antibiotics and PTA during the acute phase of infection and after defervescence., Methods: We enrolled hospitalized, non-critically ill febrile patients treated with IV antibiotics other than amoxicillin or ciprofloxacin. The study consisted of two visits: when patients had received <24 h IV treatment; and when patients had become afebrile. On both visits, patients received one additional dose of 750 mg amoxicillin, or 500 mg ciprofloxacin, depending on the presumed infection, after which serial blood samples were obtained. The primary endpoint was the ratio of the AUC during the febrile and the afebrile phase. The AUCs were considered to be equivalent when the ratio of the mean AUCs and its 90% CI was contained within the acceptance interval of 80%-125%. The secondary endpoint was PTA., Results: Forty-four patients (15 amoxicillin, 29 ciprofloxacin) completed both study visits. The median time between the two study visits was 65.8 h (range 33.8-427.4). The ratio of the mean AUCs (study visit 1/study visit 2) was 97% (90% CI of 80%-117%) for amoxicillin and 112% (90% CI of 108%-116%) for ciprofloxacin. The PTA for amoxicillin and ciprofloxacin did not differ between the two phases and was adequate to treat common pathogens., Conclusions: The acute phase of infection in non-critically ill febrile patients does not influence the exposure to, or PTA of, orally administered amoxicillin and ciprofloxacin. This might justify earlier IV-to-oral switching., (© The Author(s) 2022. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy.)

Lyme borreliosis is caused by spirochetes belonging to the Borrelia burgdorferi sensu lato group, which are transmitted by Ixodes tick species living in the temperate climate zones of the Northern Hemisphere. The clinical manifestations of Lyme borreliosis are diverse and treated with oral or intravenous antibiotics. In some patients, long-lasting and debilitating symptoms can persist after the recommended antibiotic treatment. The etiology of such persisting symptoms is under debate, and one hypothesis entails persistent infection by a subset of spirochetes after antibiotic therapy. Here, we review and appraise the experimental evidence from in vivo animal studies on the persistence of B. burgdorferi sensu lato infection after antibiotic treatment, focusing on the antimicrobial agents doxycycline and ceftriaxone. Our review indicates that some in vivo animal studies found sporadic positive cultures after antibiotic treatment. However, this culture positivity often seemed to be related to inadequate antibiotic treatment, and the few positive cultures in some studies could not be reproduced in other studies. Overall, current results from animal studies provide insufficient evidence for the persistence of viable and infectious spirochetes after adequate antibiotic treatment. Borrelial nucleic acids, on the contrary, were frequently detected in these animal studies and may thus persist after antibiotic treatment. We put forward that research into the pathogenesis of persisting complaints after antibiotic treatment for Lyme borreliosis in humans should be a top priority, but future studies should most definitely also focus on explanations other than persistent B. burgdorferi sensu lato infection after antibiotic treatment.

Background: Patients with haematological malignancies frequently endure neutropenia and gastrointestinal (GI)-mucositis after high-dose chemotherapy. In these patients, ciprofloxacin is used for Gram-negative infection prophylaxis., Objectives: We investigate ciprofloxacin pharmacokinetics after oral administration in patients with haematological malignancies and explore the impact of GI-mucositis on oral bioavailability and clearance in order to assure adequate systemic exposure., Methods: Adult haematological patients from two Dutch University Medical Centres received 500 mg twice daily oral ciprofloxacin for Gram-negative prophylaxis. The ciprofloxacin plasma concentrations were collected at various timepoints after oral ciprofloxacin administration and at various days after completion of chemotherapy. Data obtained after oral and intravenous ciprofloxacin administration in 28 healthy volunteers without mucositis served as a control group (391 samples). For haematological patients the degree of GI-mucositis was assessed using the Daily Gut Score (DGS), plasma citrulline and albumin. Data were analysed by non-linear mixed-effects modelling., Results: In total, 250 blood samples were collected in 47 patients with a wide variety of haematological malignancies between 0-30 days after start of chemotherapy. Mucositis was generally mild [DGS median (IQR) 1 (1-1) and citrulline 16 μmol/L (12-23)]. The time to Cmax was slower in haematological patients compared with healthy volunteers although no association with the degree of mucositis (defined as DGS or citrulline) could be identified. Ciprofloxacin bioavailability and clearance were 60% and 33.2 L/h, respectively., Conclusions: This study supports oral dosing of ciprofloxacin as Gram-negative infection prophylaxis in haematological patients with mild-to-moderate mucositis capable of oral intake., (© The Author(s) 2022. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy.)

Surveillance data and literature have shown a worldwide increase in infections with resistant bacteria, which has led to increased prescriptions of carbapenems, which in turn has led to increased carbapenem resistance. There is also an increasing use of carbapenems in the Netherlands, a county usually very conservative in antibiotic use. Carbapenem sparing strategies are essential in an attempt to prevent further rise of infections caused by carbapenem resistant bacteria. This article discusses carbapenem sparing strategies with old forgotten antibiotics and novel antibiotics from a Dutch perspective.

Background: Adequate antibiotic dosing may improve outcomes in critically ill patients but is challenging due to altered and variable pharmacokinetics. To address this challenge, AutoKinetics was developed, a decision support system for bedside, real-time, data-driven and personalised antibiotic dosing. This study evaluates the feasibility, safety and efficacy of its clinical implementation., Methods: In this two-centre randomised clinical trial, critically ill patients with sepsis or septic shock were randomised to AutoKinetics dosing or standard dosing for four antibiotics: vancomycin, ciprofloxacin, meropenem, and ceftriaxone. Adult patients with a confirmed or suspected infection and either lactate > 2 mmol/L or vasopressor requirement were eligible for inclusion. The primary outcome was pharmacokinetic target attainment in the first 24 h after randomisation. Clinical endpoints included mortality, ICU length of stay and incidence of acute kidney injury., Results: After inclusion of 252 patients, the study was stopped early due to the COVID-19 pandemic. In the ciprofloxacin intervention group, the primary outcome was obtained in 69% compared to 3% in the control group (OR 62.5, CI 11.4-1173.78, p < 0.001). Furthermore, target attainment was faster (26 h, CI 18-42 h, p < 0.001) and better (65% increase, CI 49-84%, p < 0.001). For the other antibiotics, AutoKinetics dosing did not improve target attainment. Clinical endpoints were not significantly different. Importantly, higher dosing did not lead to increased mortality or renal failure., Conclusions: In critically ill patients, personalised dosing was feasible, safe and significantly improved target attainment for ciprofloxacin., 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., (© 2022. The Author(s).)

Background: Precision dosing programs are promising tools for optimising antimicrobial dosing. Selecting the ideal program for local application may be challenging due to the large variety of available programs with differing characteristics., Objectives: The objectives of this study were to systematically identify available precision dosing software programs to optimize antimicrobial dosing and describe the characteristics of each program. Details on the ability of programs to provide beta-lactam dosing support was also gathered., Sources: A systematic review search strategy was used to identify candidate software programs described in the literature in Embase and PubMed. A detailed survey was then developed to identify characteristics of programs, including details on the underlying methodology driving dosing software recommendations, interface characteristics, costs and regulatory affairs. Software developers from all identified programs were invited to participate in the survey., Content: The systematic search results identified 18 programs. Fifteen developers responded to the survey (83%) and 11 programs provide dosing support for at least one beta-lactam. Fourteen programs can utilize measured drug concentrations to generate dosing recommendations, with 13 able to generate empiric dosing recommendations. Six programs integrate with local electronic health records and four are registered with at least one regulatory agency. Pharmacokinetic models in combination with Bayesian statistics is the most common methodology used to generate dosing recommendations, with 14 programs utilizing this method., Implications: There was significant variability in the available antimicrobial profiles and characteristics among dosing software programs. As healthcare providers will differ in their requirements within their local settings, clinicians should use these findings to identify potential candidate programs and, if feasible, trial these to ensure they meet their specific requirements., (Copyright © 2022 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Objectives: Evaluation of the appropriateness of the duration of antimicrobial treatment is a cornerstone of antibiotic stewardship programs, but it is time-consuming. Furthermore, it is often restricted to antibiotics prescribed during hospital admission. This study aimed to determine whether mandatory prescription-indication registration at the moment of prescribing antibiotics enables reliable automated assessment of the duration of antibiotic therapy, including post-discharge duration, limiting the need for manual chart review to data validation., Methods: Antibiotic prescription and admission data, from 1-6-2020 to 31-12-2021, were electronically extracted from the Electronic Medical Record of two hospitals using mandatory indication registration. All consecutively prescribed antibiotics of adult patients who received empiric therapy in the first 24 h of admission were merged to calculate the total length of therapy (LOT) per patient, broken down per registered indication. Endpoints were the accuracy of the data, evaluated by comparing the extracted LOT and registered indication with the clinical notes in 400 randomly selected records, and guideline adherence of treatment duration. Data were analysed using a reproducible syntax, allowing semi-automated surveillance., Results: A total of 3,466 antibiotic courses were analysed. LOT was accurately retrieved in 96% of the 400 evaluated antibiotic courses. The registered indication did not match chart review in 17% of antibiotic courses, of which only half affected the assessment of guideline adherence. On average, in 44% of patients treatment was continued post-discharge, accounting for 60% (± 19%) of their total LOT. Guideline adherence ranged from 26 to 75% across indications., Conclusions: Mandatory prescription-indication registration data can be used to reliably assess total treatment course duration, including post-discharge antibiotic duration, allowing semi-automated surveillance., (© 2022. The Author(s).)

Gentamicin is an aminoglycoside antibiotic with a small therapeutic window that is currently used primarily as part of short-term empirical combination therapy. Gentamicin dosing schemes still need refinement, especially for subpopulations where pharmacokinetics can differ from pharmacokinetics in the general adult population: obese patients, critically ill patients, paediatric patients, neonates, elderly patients and patients on dialysis. This review summarizes the clinical pharmacokinetics of gentamicin in these patient populations and the consequences for optimal dosing of gentamicin for infections caused by Gram-negative bacteria, highlighting new insights from the last 10 years. In this period, several new population pharmacokinetic studies have focused on these subpopulations, providing insights into the typical values of the most relevant pharmacokinetic parameters, the variability of these parameters and possible explanations for this variability, although unexplained variability often remains high. Both dosing schemes and pharmacokinetic/pharmacodynamic (PK/PD) targets varied widely between these studies. A gentamicin starting dose of 7 mg/kg based on total body weight (or on adjusted body weight in obese patients) appears to be the optimal strategy for increasing the probability of target attainment (PTA) after the first administration for the most commonly used PK/PD targets in adults and children older than 1 month, including critically ill patients. However, evidence that increasing the PTA results in higher efficacy is lacking; no studies were identified that show a correlation between estimated or predicted PK/PD target attainment and clinical success. Although it is unclear if performing therapeutic drug monitoring (TDM) for optimization of the PTA is of clinical value, it is recommended in patients with highly variable pharmacokinetics, including patients from all subpopulations that are critically ill (such as elderly, children and neonates) and patients on intermittent haemodialysis. In addition, TDM for optimization of the dosing interval, targeting a trough concentration of at least < 2 mg/L but preferably < 0.5-1 mg/L, has proven to reduce nephrotoxicity and is therefore recommended in all patients receiving more than one dose of gentamicin. The usefulness of the daily area under the plasma concentration-time curve for predicting nephrotoxicity should be further investigated. Additionally, more research is needed on the optimal PK/PD targets for efficacy in the clinical situations in which gentamicin is currently used, that is, as monotherapy for urinary tract infections or as part of short-term combination therapy., (© 2022. The Author(s).)

Background: Although unbound ciprofloxacin is responsible for antibacterial effects, assays measuring the unbound drug plasma concentrations are scarce. This study aimed to develop and validate a rapid, reproducible, and sensitive liquid chromatography-tandem mass spectrometry assay for the determination of total and unbound ciprofloxacin plasma concentrations., Methods: The determination of total ciprofloxacin concentrations required a 10 μL sample, while for unbound ciprofloxacin concentrations, it was 100 μL. Unbound ciprofloxacin was separated from protein-bound ciprofloxacin through ultrafiltration. A deuterated internal standard was used, and the sample preparation involved protein precipitation. The method was fully validated over a concentration range of 0.02-5.0 mg/L, according to the US Food and Drug Administration guidelines. In addition, its clinical application was demonstrated., Results: The total run time was 1.5 minutes. For total ciprofloxacin plasma concentrations, the mean accuracy ranged from 94.5% to 105.0% across the validated range, the intraday imprecision was ≤7.6%, and the interday imprecision was ≤9.8%. For unbound ciprofloxacin plasma concentrations, the mean accuracy ranged from 92.8% to 102.1% across the validated range, the intraday imprecision was ≤7.0%, and the interday imprecision was ≤9.6%. Ciprofloxacin in plasma and ultrafiltrate remained stable for at least 96 hours at room temperature, at least 4 years at -80°C, and at least 3 freeze/thaw cycles (-80°C), with a minimum interval of 24 hours., Conclusions: The presented method is precise and accurate. It has been implemented in clinical care and research projects at a university hospital, permitting rapid determination of total and unbound ciprofloxacin., Competing Interests: S. E. Geerlings has received grants from Nordic Pharma and Vifor Pharma outside of the submitted work; R. A. A. Mathôt has received grants from Baxter/Baxalta/Shire, Bayer Schering Pharma, CSL Behring, Merck Sharp & Dohme, and Zeria outside of the submitted work; R. M. van Hest received grants from Nordic Pharma outside of the submitted work. The remaining authors declare no conflict of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background and Objective: Previous pharmacokinetic (PK) studies of ciprofloxacin in intensive care (ICU) patients have shown large differences in estimated PK parameters, suggesting that further investigation is needed for this population. Hence, we performed a pooled population PK analysis of ciprofloxacin after intravenous administration using individual patient data from three studies. Additionally, we studied the PK differences between these studies through a post-hoc analysis., Methods: Individual patient data from three studies (study 1, 2, and 3) were pooled. The pooled data set consisted of 1094 ciprofloxacin concentration-time data points from 140 ICU patients. Nonlinear mixed-effects modeling was used to develop a population PK model. Covariates were selected following a stepwise covariate modeling procedure. To analyze PK differences between the three original studies, random samples were drawn from the posterior distribution of individual PK parameters. These samples were used for a simulation study comparing PK exposure and the percentage of target attainment between patients of these studies., Results: A two-compartment model with first-order elimination best described the data. Inter-individual variability was added to the clearance, central volume, and peripheral volume. Inter-occasion variability was added to clearance only. Body weight was added to all parameters allometrically. Estimated glomerular filtration rate on ciprofloxacin clearance was identified as the only covariate relationship resulting in a drop in inter-individual variability of clearance from 58.7 to 47.2%. In the post-hoc analysis, clearance showed the highest deviation between the three studies with a coefficient of variation of 14.3% for posterior mean and 24.1% for posterior inter-individual variability. The simulation study showed that following the same dose regimen of 400 mg three times daily, the area under the concentration-time curve of study 3 was the highest with a mean area under the concentration-time curve at 24 h of 58 mg·h/L compared with that of 47.7 mg·h/L for study 1 and 47.6 mg·h/L for study 2. Similar differences were also observed in the percentage of target attainment, defined as the ratio of area under the concentration-time curve at 24 h and the minimum inhibitory concentration. At the epidemiological cut-off minimum inhibitory concentration of Pseudomonas aeruginosa of 0.5 mg/L, percentage of target attainment was only 21%, 18%, and 38% for study 1, 2, and 3, respectively., Conclusions: We developed a population PK model of ciprofloxacin in ICU patients using pooled data of individual patients from three studies. A simple ciprofloxacin dose recommendation for the entire ICU population remains challenging owing to the PK differences within ICU patients, hence dose individualization may be needed for the optimization of ciprofloxacin treatment., (© 2022. The Author(s).)

Background: The advocated pharmacokinetic/pharmacodynamic (PK/PD) target for vancomycin, AUC/MIC ≥ 400 mg·h/L, may not be reached with a conventional fixed starting dose of 1000 mg in critically ill patients, but increasing the dose may cause nephrotoxicity., Objectives: To evaluate the effect of a weight-based loading dose of 25 mg/kg vancomycin on PK/PD target attainment in the first 24 h (AUC0-24) in critically ill patients and to evaluate whether this increases the risk of acute kidney injury (AKI)., Patients and Methods: A prospective observational before/after study was performed in ICU patients, comparing the percentage of vancomycin courses with AUC0-24 ≥ 400 mg·h/L and the incidence of AKI, defined as worsening of the risk, injury, failure, loss of kidney function and end-stage kidney disease (RIFLE) score. The conventional dose group received 1000 mg of vancomycin as initial dose; the loading dose group received a weight-based loading dose of 25 mg/kg. A population PK model developed using non-linear mixed-effects modelling was used to estimate AUC0-24 in all patients., Results: One hundred and four courses from 82 patients were included. With a loading dose, the percentage of courses achieving AUC0-24 ≥ 400 mg·h/L increased significantly from 53.8% to 88.0% (P = 0.0006). The percentage of patients with new-onset AKI was not significantly higher when receiving a 25 mg/kg loading dose (28.6% versus 37.8%; P = 0.48). However, the risk of AKI was significantly higher in patients achieving AUC0-24 > 400 mg·h/L compared with patients achieving AUC < 400 mg·h/L (39.0% versus 14.8%; P = 0.031)., Conclusions: A weight-based loading dose of 25 mg/kg vancomycin led to significantly more patients achieving AUC0-24 ≥ 400 mg·h/L without increased risk of AKI. However, some harm cannot be ruled out since higher exposure was associated with increased risk of AKI., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.)

Altered pharmacokinetics (PK) of hydrophilic antibiotics in critically ill patients is common, with possible consequences for efficacy and resistance. We aimed to describe ceftazidime population PK in critically ill patients with a proven or suspected Pseudomonas aeruginosa infection and to establish optimal dosing. Blood samples were collected for ceftazidime concentration measurement. A population PK model was constructed, and probability of target attainment (PTA) was assessed for targets 100% T > MIC and 100% T > 4 × MIC in the first 24 h. Ninety-six patients yielded 368 ceftazidime concentrations. In a one-compartment model, variability in ceftazidime clearance (CL) showed association with CVVH. For patients not receiving CVVH, variability in ceftazidime CL was 103.4% and showed positive associations with creatinine clearance and with the comorbidities hematologic malignancy, trauma or head injury, explaining 65.2% of variability. For patients treated for at least 24 h and assuming a worst-case MIC of 8 mg/L, PTA was 77% for 100% T > MIC and 14% for 100% T > 4 × MIC. Patients receiving loading doses before continuous infusion demonstrated higher PTA than patients who did not (100% T > MIC: 95% ( n = 65) vs. 13% ( n = 15); p < 0.001 and 100% T > 4 × MIC: 20% vs. 0%; p = 0.058). The considerable IIV in ceftazidime PK in ICU patients could largely be explained by renal function, CVVH use and several comorbidities. Critically ill patients are at risk for underexposure to ceftazidime when empirically aiming for the breakpoint MIC for P. aeruginosa . A loading dose is recommended.

Background: The systemic response to an infection might influence the pharmacokinetics of antibiotics. To evaluate the desired possibility of an earlier (< 24 h) IV-to-oral switch therapy in febrile non-ICU, hospitalized patients, a systematic review was performed to assess the effect of the initial phase of a systemic infection on the bioavailability of orally administered antibiotics in such patients., Methods: An electronic search was conducted in MEDLINE and Embase up to July 2020. Studies were selected when outcome data were collected during the initial stage of a febrile disease. Outcome data were (maximum) serum concentrations, time of achieving maximum serum concentration, and the area-under-the-plasma-concentration-time curve or bioavailability of orally administered antibiotics. Risk of bias was assessed., Results: We identified 9 studies on 6 antibiotics. Ciprofloxacin was the most frequently studied drug. Outcomes of the studies were heterogeneous and generally had a high risk of bias. Three small studies, two on ciprofloxacin and one on clarithromycin, compared the pharmacokinetics of febrile patients with those of clinically recovered patients and suggested that bioavailability was not altered in these patients. Other studies either compared the pharmacokinetics in febrile patients with reported pharmacokinetic values from earlier studies in healthy volunteers (n = 2), or provided no comparison at all and were non-conclusive (n = 4)., Conclusion: There is a clear knowledge gap regarding the bioavailability of orally administered antibiotics in non-ICU patients during the initial phase of a systemic infection. Well-designed studies on this topic are necessary to elucidate whether patients can benefit from the advantages of an earlier IV-to-oral switch.

Background: There is inconsistency between many guidelines in the recommended dose reduction of renally cleared antibiotics in patients with impaired renal function., Objectives: This systematic review summarizes the available evidence on the adequacy of the recommended dose reduction in terms of achieving sufficient antibiotic drug exposure or pharmacokinetic/pharmacodynamic target attainment after treatment with these reduced doses., Data Sources: We systematically searched Ovid Medline and Embase from inception (respectively 1946 and 1947) through July 2019., Study Eligibility Criteria: All studies reporting antibiotic drug exposure and/or pharmacokinetic/pharmacodynamic (PK/PD) target attainment after dose reduction of antibiotics in patients with impaired renal function., Participants: Adult patients with or without infections., Interventions: Administration of reduced doses of antibiotics (orally, intravenously or intramuscularly)., Methods: The reduced dose was considered adequate when the most relevant parameters of drug exposure or PK/PD target attainment in patients with impaired renal function were within a range of 80% to 125% of that patients with adequate renal function receiving a regular dose (reference) or when PK/PD target attainment was attained in at least 90% of the patients with impaired renal function, regardless of the lack of a reference group., Results: Twenty-seven of the 4202 identified studies were included. The quality of 15 of 27 studies was fair, and most studies were of β-lactams (12/27). Best evidence was available for meropenem: four studies were included, of which two studies were of good quality. Drug exposure for meropenem is 158% to 286% higher in patients with impaired renal function receiving reduced doses compared to patients with adequate renal function receiving regular doses. For all other antibiotics, a maximum of one good-quality study could be identified., Conclusions: No good-quality evidence on the recommended dose reduction of renally cleared antibiotics in patients with impaired renal function is present, with the exception of meropenem., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Aims: To explore the optimal data sampling scheme and the pharmacokinetic (PK) target exposure on which dose computation is based in the model-based therapeutic drug monitoring (TDM) practice of vancomycin in intensive care (ICU) patients., Methods: We simulated concentration data for 1 day following four sampling schemes, C min , C max + C min , C max + C mid-interval + C min , and rich sampling where a sample was drawn every hour within a dose interval. The datasets were used for Bayesian estimation to obtain PK parameters, which were used to compute the doses for the next day based on five PK target exposures: AUC 24 = 400, 500, and 600 mg·h/L and C min = 15 and 20 mg/L. We then simulated data for the next day, adopting the computed doses, and repeated the above procedure for 7 days. Thereafter, we calculated the percentage error and the normalized root mean square error (NRMSE) of estimated against "true" PK parameters, and the percentage of optimal treatment (POT), defined as the percentage of patients who met 400 ≤ AUC 24 ≤ 600 mg·h/L and C min ≤ 20 mg/L., Results: PK parameters were unbiasedly estimated in all investigated scenarios and the 6-day average NRMSE were 32.5%/38.5% (CL/V, where CL is clearance and V is volume of distribution) in the trough sampling scheme and 27.3%/26.5% (CL/V) in the rich sampling scheme. Regarding POT, the sampling scheme had marginal influence, while target exposure showed clear impacts that the maximum POT of 71.5% was reached when doses were computed based on AUC 24 = 500 mg·h/L., Conclusions: For model-based TDM of vancomycin in ICU patients, sampling more frequently than taking only trough samples adds no value and dosing based on AUC 24 = 500 mg·h/L lead to the best POT., (© 2020 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Hemophilia A and B are bleeding disorders caused by a deficiency of clotting factor VIII and IX, respectively. Patients with severe hemophilia (< 0.01 IU mL -1 ) and some patients with moderate hemophilia (0.01-0.05 IU mL -1 ) administer clotting factor concentrates prophylactically. Desmopressin (D-amino D-arginine vasopressin) can be applied in patients with non-severe hemophilia A. The aim of administration of factor concentrates or desmopressin is the prevention or cessation of bleeding. Despite weight-based dosing, it has been demonstrated that factor concentrates still exhibit considerable pharmacokinetic variability. Population pharmacokinetic analyses, in which this variability is quantified and explained, are increasingly performed in hemophilia research. These analyses can assist in the identification of important patient characteristics and can be applied to perform patient-tailored dosing. This review aims to present and discuss the population pharmacokinetic analyses that have been conducted to develop population pharmacokinetic models describing factor levels after administration of factor VIII or factor IX concentrates or D-amino D-arginine vasopressin. In total, 33 publications were retrieved from the literature. Two approaches were applied to perform population pharmacokinetic analyses, the standard two-stage approach and non-linear mixed-effect modeling. Using the standard two-stage approach, four population pharmacokinetic models were established describing factor VIII levels. In the remaining 29 analyses, the non-linear mixed-effect modeling approach was applied. NONMEM was the preferred software to establish population pharmacokinetic models. In total, 18 population pharmacokinetic analyses were conducted on the basis of data from a single product. From all available population pharmacokinetic analyses, 27 studies also included data from pediatric patients. In the majority of the population pharmacokinetic models, the population pharmacokinetic parameters were allometrically scaled using actual body weight. In this review, the available methods used for constructing the models, key features of these models, patient population characteristics, and established covariate relationships are described in detail.

Limited prospective data on pharmacokinetic/pharmacodynamic (PK/PD) target attainment of ciprofloxacin in patients with adequate and impaired renal function (eGFR <30 mL/min/1.73m 2 ) are available in the literature. We aimed to investigate whether the PK/PD target (AUC/MIC ≥125) is attained in patients with adequate and impaired renal function receiving regular and reduced ciprofloxacin doses. This prospective observational cohort study included adult patients on general wards treated with ciprofloxacin. Three blood samples per patient were obtained for ciprofloxacin concentration measurement. Individual AUCs were calculated using a population PK model developed by non-linear mixed-effects modelling. Forty patients were included, of whom eight had impaired renal function and were treated with a guideline-recommended reduced dose. Using the clinical breakpoint MIC of the most isolated bacteria (Escherichia coli, 0.25 mg/L), AUC 0-24 /MIC ≥125 was attained in 13/32 (41%) patients with adequate renal function receiving regular doses and in 1/8 (13%) patients with impaired renal function receiving reduced doses. Median drug exposure (AUC 0-24 ) for patients with impaired renal function was 19.0 [interquartile range (IQR) 14.2-23.3] mg/L•h, which was statistically significantly lower than that for patients with adequate renal function [29.3 (IQR 25.0-36.0) mg/L•h] (P < 0.01). AUC 0-24 /MIC ≥125 is not attained in the majority of adult patients on general wards for clinically relevant bacteria with MICs at or just below the clinical breakpoint. The risk of not attaining the target appears to be highest in patients with impaired renal function receiving guideline-recommended reduced doses, as drug exposure is significantly lower in these patients., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Initial appropriate anti-infective therapy is associated with improved outcomes in patients with severe infections. In critically ill patients, altered pharmacokinetic (PK) behaviour is common and known to influence the achievement of PK/pharmacodynamic targets., Objectives: To describe population PK and optimized dosing regimens for flucloxacillin in critically ill patients., Methods: First, we developed a population PK model, estimated between-patient variability (BPV) and identified covariates that could explain BPV through non-linear mixed-effects analysis, using total and unbound concentrations obtained from 35 adult critically ill patients treated with intermittent flucloxacillin. Second, we validated the model using external datasets from two different countries. Finally, frequently prescribed dosing regimens were evaluated using Monte Carlo simulations., Results: A two-compartment model with non-linear protein binding was developed and validated. BPV of the maximum binding capacity decreased from 42.2% to 30.4% and BPV of unbound clearance decreased from 88.1% to 71.6% upon inclusion of serum albumin concentrations and estimated glomerular filtration rate (eGFR; by CKD-EPI equation), respectively. PTA (target of 100%fT>MIC) was 91% for patients with eGFR of 33 mL/min and 1 g q6h, 87% for patients with eGFR of 96 mL/min and 2 g q4h and 71% for patients with eGFR of 153 mL/min and 2 g q4h., Conclusions: For patients with high creatinine clearance who are infected with moderately susceptible pathogens, therapeutic drug monitoring is advised since there is a risk of underexposure to flucloxacillin. Due to the non-linear protein binding of flucloxacillin and the high prevalence of hypoalbuminaemia in critically ill patients, dose adjustments should be based on unbound concentrations., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.)

Purpose: Bayesian forecasting is crucial for model-based dose optimization based on therapeutic drug monitoring (TDM) data of vancomycin in intensive care (ICU) patients. We aimed to evaluate the performance of Bayesian forecasting using maximum a posteriori (MAP) estimation for model-based TDM., Methods: We used a vancomycin TDM data set (n = 408 patients). We compared standard MAP-based Bayesian forecasting with two alternative approaches: (i) adaptive MAP which handles data over multiple iterations, and (ii) weighted MAP which weights the likelihood contribution of data. We evaluated the percentage error (PE) for seven scenarios including historical TDM data from the preceding day up to seven days., Results: The mean of median PEs of all scenarios for the standard MAP, adaptive MAP and weighted MAP method were - 7.7%, -4.5% and - 6.7%. The adaptive MAP also showed the narrowest inter-quartile range of PE. In addition, regardless of MAP method, including historical TDM data further in the past will increase prediction errors., Conclusions: The proposed adaptive MAP method outperforms standard MAP in predictive performance and may be considered for improvement of model-based dose optimization. The inclusion of historical data beyond either one day (standard MAP and weighted MAP) or two days (adaptive MAP) reduces predictive performance.

Background: The pharmacokinetic (PK) data of ganciclovir (GCV), a first-line antiviral treatment for cytomegalovirus infections, in critically ill patients are limited. This study aimed at characterizing GCV population PK and interindividual variability (IIV) in intensive care unit (ICU) patients. Secondary objectives were to identify patient characteristics responsible for IIV and simulate GCV exposure for different dosing regimens., Method: In this retrospective observational study, clinical data and serum GCV levels were collected from ICU patients on intravenous GCV. PK modeling, covariate analyses, and explorative Monte Carlo dosing simulations (MCS) were performed using nonlinear mixed-effects modeling. Bootstrap and visual predictive checks were used to determine model adequacy., Results: In total, 128 GCV measurements were obtained from 34 patients. GCV PK conformed to a 1-compartment model with first-order elimination. After multivariate analyses, only the estimated glomerular filtration rate calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula (P < 0.001) was included as a covariate. In the final model, the estimated clearance (CL) and volume of distribution (V1) were 2.3 L/h and 42 L, respectively, for a patient with the median CKD-EPI of the population (65 mL/min per 1.73 m). The association between CKD-EPI and CL decreased the residual variability from 0.56 to 0.43 and V1-IIV from 114% to 80%, whereas CL-IIV changed from 43% to 47%. MCS revealed that a substantial number of patients may not achieve the GCV PK/pharmacodynamic target trough level (>1.5 mg/L) when administering the label-recommended dose reductions for patients with CKD-EPI <50 mL/min., Conclusions: A large IIV was observed in GCV PK among ICU patients. CKD-EPI could partially explain the IIV, although a large part of the variability remains unclear. MCS suggested that recommended dose reductions for CKD-EPI <50 mL/min may lead to subtherapeutic plasma GCV levels in these patients.

Objectives: Antimicrobial Stewardship Programs commonly have an in-hospital focus. Little is known about the quality of antimicrobial use in hospital outpatient clinics. We investigated the extent and appropriateness of antimicrobial prescriptions in the outpatient clinics of three hospitals., Methods: From June 2018 to January 2019, we performed ten point prevalence surveys in outpatient clinics of one university hospital and two large teaching hospitals. All prophylactic and therapeutic prescriptions were retrieved from the electronic medical records. Appropriateness was defined as being in accordance with guidelines. Furthermore, we investigated the extent to which the dose was adjusted to renal function and documentation of an antibiotic plan in the case notes., Results: We retrieved 720 prescriptions for antimicrobial drugs, of which 173 prescriptions (24%) were prophylactic. A guideline was present for 95% of prescriptions, of which the guideline non-adherence rate was 25.6% (n = 42/164) for prophylaxis and 43.1% (n = 224/520) for therapy. Of all inappropriate prescriptions (n = 266), inappropriate prescriptions for skin and soft tissue infections (n = 60/226) and amoxicillin-clavulanic acid (n = 67/266) made up the largest proportion. In only 13 of 138 patients with impaired or unknown renal function the dosage regimen was adjusted. Amoxicillin-clavulanic acid was the drug for which most often renal function was not taken into account. In 94.6% of prescriptions the antibiotic plan was documented., Conclusions: In hospital outpatient clinics, a substantial part of therapeutics were inappropriately prescribed. Amoxicillin-clavulanic acid was the most inappropriately prescribed drug, due to non-adherence to the guidelines and because dose adjustment to renal function was often not considered.

Background: In patients with haemophilia A (HA) perioperative dosing of factor VIII (FVIII) concentrate is based on body weight, historical FVIII level, in vivo recovery and FVIII level target values. In moderate and severe HA patients, this dosing regimen frequently leads to perioperative FVIII levels below and above target. This has not yet been evaluated in mild HA patients., Objectives: To evaluate perioperative FVIII concentrate treatment in mild HA patients and to assess the frequency of FVIII levels below or above target., Patients/methods: This retrospective single-centre study collected data from medical files of mild HA patients undergoing surgery and treated with FVIII concentrate. FVIII levels were compared to their target ranges and predictive factors for levels outside the target ranges were determined by logistic regression., Results: Fifty surgeries performed in 34 patients were evaluated. Median age was 47 years and median historical FVIII level was 0.14 IU/mL. Preoperative peak FVIII level was above or below the target range in 80% and 6.7% of surgeries, respectively. Postoperatively, the percentages above and below target trough ranges were 55.8% and 12.8%. Patients with blood group 0 had the highest risk on the preoperative peak FVIII level being above target. In addition, patients who had a preoperative baseline FVIII level of >0.10 IU/mL higher than their historical FVIII level had a higher preoperative peak FVIII level than patients without this increase., Conclusions: Dosing above FVIII target ranges with FVIII concentrates occurs frequently during perioperative treatment of mild HA patients. These results underline the necessity for better patient-tailored treatment., (© 2019 John Wiley & Sons Ltd.)

Introduction : Since the majority of bacterial infections occur at sites outside the bloodstream, antibiotic tissue concentrations are of significant relevance to optimize treatment. The aim of this review is to aid the clinician in choosing optimal regimens for the treatment of extravascular infections. Areas covered : We discuss the principles of antibiotic tissue penetration and assess different approaches to obtain data on this subject. Finally, we present tissue penetration data for several relevant groups of antibiotic agents in a number of extravascular sites. Data were obtained from an extensive literature search in PubMed until February 2019. Expert opinion : There is still a long way to go before reliable information about tissue penetration of antibiotics is sufficiently available to serve as a basis for the design of optimal strategies for drug and dose selection. At this moment, there is a lack of robust data on tissue penetration, where both the sampling and measurement techniques as well as the relationship between tissue concentrations and clinical outcome of antibiotic treatment have to be better defined.

Dosing of vancomycin is often guided by therapeutic drug monitoring and population pharmacokinetic models in the intensive care unit (ICU). The validity of these models is crucial, as ICU patients have marked pharmacokinetic variability. Therefore, we set out to evaluate the predictive performance of published population pharmacokinetic models of vancomycin in ICU patients. The PubMed database was used to search for population pharmacokinetic models of vancomycin in adult ICU patients. The identified models were evaluated in two independent data sets which were collected from two large hospitals in the Netherlands (Amsterdam UMC, Location VUmc, and OLVG Oost). We also tested a one-compartment model with fixed values for clearance and volume of distribution, in which a clinical standard dosage regimen (SDR) was mimicked to assess its predictive performance. Prediction error was calculated to assess the predictive performance of the models. Six models plus the SDR model were evaluated. The model of Roberts et al. (J. A. Roberts, F. S. Taccone, A. A. Udy, J.-L. Vincent, F. Jacobs, and J. Lipman, Antimicrob Agents Chemother 55:2704-2709, 2011, https://doi.org/10.1128/AAC.01708-10) performed satisfactorily, with mean and median values of prediction error of 5.1% and -7.5%, respectively, for Amsterdam UMC, Location VUmc, patients, and -12.6% and -17.2% respectively, for OLVG Oost patients. The other models, including the SDR model, yielded high mean values (-49.7% to 87.7%) and median values (-56.1% to 66.1%) for both populations. In conclusion, only the model of Roberts et al. was able to validly predict the concentrations of vancomycin for our data, whereas other models and standard dosing were largely inadequate. Extensive evaluation should precede the adoption of any model in clinical practice for ICU patients., (Copyright © 2019 American Society for Microbiology.)

Introduction: Haemophilia A is an inherited bleeding disorder characterised by factor VIII (FVIII) deficiency. In patients with non-severe haemophilia A, surgery and bleeding are the main indications for treatment with FVIII concentrate. A recent study reported that standard dosing frequently results in FVIII levels (FVIII:C) below or above FVIII target ranges, leading to respectively a bleeding risk or excessive costs. In addition, FVIII concentrate treatment carries a risk of development of neutralising antibodies. An alternative is desmopressin, which releases endogenous FVIII and von Willebrand factor. In most patients with non-severe haemophilia A, desmopressin alone is not enough to achieve FVIII target levels during surgery or bleeding. We hypothesise that combined pharmacokinetic (PK)-guided administration of desmopressin and FVIII concentrate may improve dosing accuracy and reduces FVIII concentrate consumption., Methods and Analysis: In the DAVID study, 50 patients with non-severe haemophilia A (FVIII:C ≥0.01 IU/mL) with a bleeding episode or undergoing surgery will receive desmopressin and FVIII concentrate combination treatment. The necessary dose of FVIII concentrate to reach FVIII target levels after desmopressin administration will be calculated with a population PK model. The primary endpoint is the proportion of patients reaching FVIII target levels during the first 72 hours after start of the combination treatment. This approach was successfully tested in one pilot patient who received perioperative combination treatment., Ethics and Dissemination: The DAVID study was approved by the medical ethics committee of the Erasmus MC. Results of the study will be communicated trough publication in international scientific journals and presentation at (inter)national conferences., Trial Registration Number: NTR5383; Pre-results., Competing Interests: Competing interests: LMS: received reimbursement from CSL-Behring for attending a symposium, not related to this study. MHC: received unrestricted research/educational funding for various projects as well as travel fees from the following institutions and companies: ZonMW, Innovatiefonds, Pfizer, Baxalta/Shire, Bayer Schering Pharma, Novo Nordisk, Novartis, Roche and CSL Behring, all not related to this study. RMvH, EAMB, MC, MHED, LN, SP: nothing to disclose relevant to the DAVID study. KF: is a member of the European Hemophilia Treatment and Standardization Board sponsored by Baxter, has received unrestricted research grants from CSL Behring and Bayer and has given lectures at educational symposiums organized by Pfizer, Bayer and Baxter. JE: received research funding from CSL Behring and honorarium for educational activity from Roche, not related to this study. BAPL-vG: received unrestricted educational grants from Baxter and CSL Behring and speaker fees from Sanquin. KM: research support from Bayer, Sanquin and Pfizer; speaker fees from Bayer, Sanquin, Boehringer Ingelheim, BMS and Aspen; consulting fees from Uniqure, not related to this study; FWGL: received unrestricted research grants from CSL-Behring and Baxalta/Shire not related to this study. He is consulant for Shire, NovoNordisk and UniQure. Fees go to the university. RAAM: received personal fees from Merck Sharp & Dohme and Zeria and grants from Bayer, UCB Pharma and Hoffman La Roche with no involvement in this study. MJHAK: received unrestricted research grants from Pfizer, Innovatiefonds and Ferring with no involvement in this study., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Hemophilia A and hemophilia B are hereditary bleeding disorders, caused by a deficiency of clotting factor VIII or clotting factor IX, respectively. To treat and prevent bleedings, patients can administer clotting factor concentrates (hemophilia A and B) or desmopressin (hemophilia A). Both clotting factor concentrates and desmopressin are currently dosed according to the patients' body weight. However, clotting factor concentrates exhibit considerable pharmacokinetic (PK) variability. Therefore, several alternative dosing strategies to individualize dosing of clotting factor concentrates and desmopressin in hemophilia A and B have been proposed. In this study, a review of the existing literature on the individualization of dosing based on PK guidance was performed. In total, 79 articles were included. The methods to individualize dosing were divided into 3 categories: (1) methods using clinical parameters, (2) empirical individual PK-guided methods, and (3) maximum a posteriori (MAP) Bayesian estimation methods. The clinical parameter mainly used to individualize dosing is bleeding phenotype. Dosing based on bleeding phenotype may decrease clotting factor consumption. However, with this method, it is not possible to individualize on-demand dosing during bleeding events or in the perioperative setting. Empirical individual PK-guided methods can be used both for prevention and treatment of bleedings. These methods include dose individualization using a nomogram and individualized in vivo recovery. In the perioperative setting, adjustment of the rate of continuous infusion can be applied to obtain a specific target level. The final category, MAP Bayesian estimation methods, relies on the availability of a population PK model. In total, 22 population PK models describing clotting factor concentrate or desmopressin dosing are currently available in literature. MAP Bayesian estimates can be used to calculate the individualized doses required to achieve or maintain a target level in every setting. The application of PK-guided and pharmacodynamic-guided dosing of clotting factor concentrates and desmopressin seems promising, although further investigation is warranted. Prospective studies analyzing its potential benefit are on the way.

In sub-Saharan Africa (SSA), gentamicin is commonly used for severe infections in non-intensive-care-unit (ICU) settings, but pharmacokinetic and pharmacodynamic data for this specific population are lacking. We performed a population pharmacokinetic study in an adult Mozambican non-ICU hospital population treated with gentamicin ( n  = 48) and developed a pharmacokinetic model using nonlinear mixed-effects modeling. Simulations showed that non-ICU patient populations in SSA may be at substantial risk for underexposure to gentamicin during routine once-daily dosing., (Copyright © 2019 American Society for Microbiology.)