Physiologically Based Pharmacokinetic Modelling in Critically Ill Children Receiving Anakinra While on Extracorporeal Life Support.

BACKGROUND AND OBJECTIVE: Because of the pathophysiological changes associated with critical illness and the use of extracorporeal life support (ECLS) such as continuous renal replacement therapy (CRRT) and extracorporeal membrane oxygenation (ECMO), the pharmacokinetics of drugs are often altered. The objective of this study was to develop a physiologically based pharmacokinetic (PBPK) model for anakinra in children that accounts for the physiological changes associated with critical illness and ECLS technology to guide appropriate pharmacotherapy. METHODS: A PBPK model for anakinra was first developed in healthy individuals prior to extrapolating to critically ill children receiving ECLS. To account for the impact of anakinra clearance by the dialysis circuit, a CRRT compartment was added to the pediatric PBPK model and parameterized using data from a previously published ex-vivo study. Additionally, an ECMO compartment was added to the whole-body structure to create the final anakinra ECLS-PBPK model. The final model structure was validated by comparing predicted concentrations with observed patient data. Due to limited information in guiding anakinra dosing in this population, in-silico dose simulations were conducted to provide baseline recommendations. RESULTS: By accounting for changes in physiology and the addition of ECLS compartments, the final ECLS-PBPK model predicted the observed plasma concentrations in an adolescent receiving subcutaneous anakinra. Furthermore, dosing simulations suggest that anakinra exposure in adolescents receiving ECLS is similar to that in healthy counterparts. CONCLUSION: The anakinra ECLS-PBPK model developed in this study is the first to predict plasma concentrations in a population receiving simultaneous CRRT and ECMO. Dosing simulations provided may be used to inform anakinra use in critically ill children and guide future clinical trial planning.

Extraction of ketamine and dexmedetomidine by extracorporeal life support circuits☠.

BACKGROUND: Patients supported with extracorporeal life support (ECLS) circuits such as ECMO and CRRT often require high doses of sedatives and analgesics, including ketamine and dexmedetomidine. Concentrations of many medications are affected by ECLS circuits through adsorption to the circuit components, dialysis, as well as the large volume of blood used to prime the circuits. However, the impact of ECLS circuits on ketamine and dexmedetomidine pharmacokinetics has not been well described. This study determined ketamine and dexmedetomidine extraction by extracorporeal circuits in an ex-vivo system. METHODS: Medication was administered at therapeutic concentration to blood-primed, closed-loop ex-vivo ECMO and CRRT circuits. Drug concentrations were measured in plasma, hemofiltrate, and control samples at multiple time points throughout the experiments. At each sample time point, the percentage of drug recovery was calculated. RESULTS: Ketamine plasma concentration in the ECMO and CRRT circuits decreased rapidly, with 43.8% recovery (SD = 0.6%) from ECMO circuits after 8 h and 3.3% (SD = 1.8%) recovery from CRRT circuits after 6 h. Dexmedetomidine was also cleared from CRRT circuits, with 20.3% recovery (SD = 1.8%) after 6 h. Concentrations of both medications were very stable in the control experiments, with approximately 100% drug recovery of both ketamine and dexmedetomidine after 6 h. CONCLUSION: Ketamine and dexmedetomidine concentrations are significantly affected by ECLS circuits, indicating that dosing adjustments are needed for patients supported with ECMO and CRRT.

Safety and feasibility pilot study of continuous low-dose maternal supplemental oxygen in fetal single ventricle heart disease.

OBJECTIVE: Fetuses with single ventricle physiology (SVP) exhibit reductions in fetal cerebral oxygenation, with associated delays in fetal brain growth and neurodevelopmental outcomes. Maternal supplemental oxygen (MSO) has been proposed to improve fetal brain growth, but current evidence on dosing, candidacy and outcomes is limited. In this pilot study, we evaluated the safety and feasibility of continuous low-dose MSO in the setting of SVP. METHODS: This single-center, open-label, pilot phase-1 safety and feasibility clinical trial included 25 pregnant individuals with a diagnosis of fetal SVP. Participants self-administered continuous MSO using medical-grade oxygen concentrators for up to 24 h per day from the second half of gestation until delivery. The primary aim was the evaluation of the safety profile and feasibility of MSO. A secondary preliminary analysis was performed to assess the impact of MSO on the fetal circulation using echocardiography and late-gestation cardiovascular magnetic resonance imaging. Early outcomes were assessed, including perinatal growth and preoperative brain injury, and neurodevelopmental outcomes were assessed at 18 months using the Bayley Scales of Infant and Toddler Development 3rd edition, and compared with those of a contemporary fetal SVP cohort (n = 217) that received the normal standard of care (SOC). RESULTS: Among the 25 participants, the median maternal age at conception was 35 years, and fetal SVP diagnoses included 16 with right ventricle dominant, eight with left ventricle dominant and one with indeterminate ventricular morphology. Participants started the trial at approximately 29 + 2 weeks' gestation and self-administered MSO for a median of 16.1 h per day for 63 days, accumulating a median of 1029 h of oxygen intake from enrolment until delivery. The only treatment-associated adverse events were nasal complications that were resolved typically by attaching a humidifier unit to the oxygen concentrator. No premature closure of the ductus arteriosus or unexpected fetal demise was observed. In the secondary analysis, MSO was not associated with any changes in fetal growth, middle cerebral artery pulsatility index, cerebroplacental ratio or head-circumference-to-abdominal-circumference ratio Z-scores over gestation compared with SOC. Although MSO was associated with changes in umbilical artery pulsatility index Z-score over the study period compared with SOC (P = 0.02), this was probably due to initial baseline differences in placental resistance. At late-gestation cardiovascular magnetic resonance imaging, MSO was not associated with an increase in fetal cerebral oxygen delivery. Similarly, no differences were observed in neonatal outcomes, including preoperative brain weight Z-score and brain injury, mortality by 18 months of age and neurodevelopmental outcomes at 18 months of age. CONCLUSIONS: This pilot phase-1 clinical trial indicates that low-dose MSO therapy is safe and well tolerated in pregnancies diagnosed with fetal SVP. However, our protocol was not associated with an increase in fetal cerebral oxygen delivery or improvements in early neurological or neurodevelopmental outcomes. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Maximum likelihood estimation of renal transporter ontogeny profiles for pediatric PBPK modeling.

Optimal treatment of infants with many renally cleared drugs must account for maturational differences in renal transporter (RT) activity. Pediatric physiologically-based pharmacokinetic (PBPK) models may incorporate RT activity, but this requires ontogeny profiles for RT activity in children, especially neonates, to predict drug disposition. Therefore, RT expression measurements from human kidney postmortem cortical tissue samples were normalized to represent a fraction of mature RT activity. Using these data, maximum likelihood estimated the distributions of RT activity across the pediatric age spectrum, including preterm and term neonates. PBPK models of four RT substrates (acyclovir, ciprofloxacin, furosemide, and meropenem) were evaluated with and without ontogeny profiles using average fold error (AFE), absolute average fold error (AAFE), and proportion of observations within the 5-95% prediction interval. Novel maximum likelihood profiles estimated ontogeny distributions for the following RT: OAT1, OAT3, OCT2, P-gp, URAT1, BCRP, MATE1, MRP2, MRP4, and MATE-2 K. Profiles for OAT3, P-gp, and MATE1 improved infant furosemide and neonate meropenem PBPK model AFE from 0.08 to 0.70 and 0.53 to 1.34 and model AAFE from 12.08 to 1.44 and 2.09 to 1.36, respectively, and improved the percent of data within the 5-95% prediction interval from 48% to 98% for neonatal ciprofloxacin simulations, respectively. Even after accounting for other critical population-specific maturational differences, novel RT ontogeny profiles substantially improved neonatal PBPK model performance, providing validated estimates of maturational differences in RT activity for optimal dosing in children.

Evaluation of high dose N- Acetylcysteine on airway inflammation and quality of life outcomes in adults with bronchiectasis: A randomised placebo-controlled pilot study.

BACKGROUND: High dose N acetylcysteine (NAC), a mucolytic, anti-inflammatory and antioxidant agent has been shown to significantly reduce exacerbations, and improve quality of life in placebo controlled, double blind randomised (RCT) studies in patients with COPD, and in an open, randomised study in bronchiectasis. In this pilot, randomised, double-blind, placebo-controlled study, we wished to investigate the feasibility of a larger clinical trial, and the anti-inflammatory and clinical benefits of high dose NAC in bronchiectasis. AIMS: Primary outcome: to assess the efficacy of NAC 2400 mg/day at 6 weeks on sputum neutrophil elastase (NE), a surrogate marker for exacerbations. Secondary aims included assessing the efficacy of NAC on sputum MUC5B, IL-8, lung function, quality of life, and adverse effects. METHODS: Participants were randomised to receive 2400 mg or placebo for 6 weeks. They underwent 3 visits: at baseline, week 3 and week 6 where clinical and sputum measurements were assessed. RESULTS: The study was stopped early due to the COVID pandemic. In total 24/30 patients were recruited, of which 17 completed all aspects of the study. Given this, a per protocol analysis was undertaken: NAC (n = 9) vs placebo (n = 8): mean age 72 vs 62 years; male gender: 44% vs 50%; baseline median FEV11.56 L (mean 71.5 % predicted) vs 2.29L (mean 82.2% predicted). At 6 weeks, sputum NE fell by 47% in the NAC group relative to placebo (mean fold difference (95%CI: 0.53 (0.12,2.42); MUC5B increased by 48% with NAC compared with placebo. Lung function, FVC improved significantly with NAC compared with placebo at 6 weeks (mean fold difference (95%CI): 1.10 (1.00, 1.20), p = 0.045. Bronchiectasis Quality of life measures within the respiratory and social functioning domains demonstrated clinically meaningful improvements, with social functioning reaching statistical significance. Adverse effects were similar in both groups. CONCLUSION: High dose NAC exhibits anti-inflammatory benefits, and improvements in aspects of quality of life and lung function measures. It is safe and well tolerated. Further larger placebo controlled RCT's are now warranted examining its role in reducing exacerbations.

Meropenem extraction by ex vivo extracorporeal life support circuits.

BACKGROUND: Meropenem is a broad-spectrum carbapenem-type antibiotic commonly used to treat critically ill patients infected with extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae. As many of these patients require extracorporeal membrane oxygenation (ECMO) and/or continuous renal replacement therapy (CRRT), it is important to understand how these extracorporeal life support circuits impact meropenem pharmacokinetics. Based on the physicochemical properties of meropenem, it is expected that ECMO circuits will minimally extract meropenem, while CRRT circuits will rapidly clear meropenem. The present study seeks to determine the extraction of meropenem from ex vivo ECMO and CRRT circuits and elucidate the contribution of different ECMO circuit components to extraction. METHODS: Standard doses of meropenem were administered to three different configurations (n = 3 per configuration) of blood-primed ex vivo ECMO circuits and serial sampling was conducted over 24 h. Similarly, standard doses of meropenem were administered to CRRT circuits (n = 4) and serial sampling was conducted over 4 h. Meropenem was administered to separate tubes primed with circuit blood to serve as controls to account for drug degradation. Meropenem concentrations were quantified, and percent recovery was calculated for each sample. RESULTS: Meropenem was cleared at a similar rate in ECMO circuits of different configurations (n = 3) and controls (n = 6), with mean (standard deviation) recovery at 24 h of 15.6% (12.9) in Complete circuits, 37.9% (8.3) in Oxygenator circuits, 47.1% (8.2) in Pump circuits, and 20.6% (20.6) in controls. In CRRT circuits (n = 4) meropenem was cleared rapidly compared with controls (n = 6) with a mean recovery at 2 h of 2.36% (1.44) in circuits and 93.0% (7.1) in controls. CONCLUSION: Meropenem is rapidly cleared by hemodiafiltration during CRRT. There is minimal adsorption of meropenem to ECMO circuit components; however, meropenem undergoes significant degradation and/or plasma metabolism at physiological conditions. These ex vivo findings will advise pharmacists and physicians on the appropriate dosing of meropenem.

Anakinra Removal by Continuous Renal Replacement Therapy: An Ex Vivo Analysis.

OBJECTIVES: Patients with sepsis are at significant risk for multiple organ dysfunction, including the lungs and kidneys. To manage the morbidity associated with kidney impairment, continuous renal replacement therapy (CRRT) may be required. The extent of anakinra pharmacokinetics in CRRT remains unknown. The objectives of this study were to investigate the anakinra-circuit interaction and quantify the rate of removal from plasma. DESIGN: The anakinra-circuit interaction was evaluated using a closed-loop ex vivo CRRT circuit. CRRT was performed in three phases based on the method of solute removal: 1) hemofiltration, 2) hemodialysis, and 3) hemodiafiltration. Standard control samples of anakinra were included to assess drug degradation. SETTING: University research laboratory. PATIENTS: None. INTERVENTIONS: Anakinra was administered to the CRRT circuit and serial prefilter blood samples were collected along with time-matched control and hemofiltrate samples. Each circuit was run in triplicate to assess inter-run variability. Concentrations of anakinra in each reference fluid were measured by enzyme-linked immunosorbent assay. Transmembrane filter clearance was estimated by the product of the sieving coefficient/dialysate saturation constant and circuit flow rates. MEASUREMENTS AND MAIN RESULTS: Removal of anakinra from plasma occurred within minutes for each CRRT modality. Average drug remaining (%) in plasma following anakinra administration was lowest with hemodiafiltration (34.9%). The average sieving coefficient was 0.34, 0.37, and 0.41 for hemodiafiltration, hemofiltration, and hemodialysis, respectively. Transmembrane clearance was fairly consistent across each modality with the highest during hemodialysis (5.53 mL/min), followed by hemodiafiltration (4.99 mL/min), and hemofiltration (3.94 mL/min). Percent drug remaining within the control samples (93.1%) remained consistent across each experiment, indicating negligible degradation within the blood. CONCLUSIONS: The results of this analysis are the first to demonstrate that large molecule therapeutic proteins such as anakinra, are removed from plasma with modern CRRT technology. Current dosing recommendations for patients with severe renal impairment may result in subtherapeutic anakinra concentrations in those receiving CRRT.

Streamlining the Detection of Human Thyroid Receptor Ligand Interactions with XL1-Blue Cell-Free Protein Synthesis and Beta-Galactosidase Fusion Protein Biosensors.

Thyroid receptor signaling controls major physiological processes and disrupted signaling can cause severe disorders that negatively impact human life. Consequently, methods to detect thyroid receptor ligands are of great toxicologic and pharmacologic importance. Previously, we reported thyroid receptor ligand detection with cell-free protein synthesis of a chimeric fusion protein composed of the human thyroid receptor beta (hTRß) receptor activator and a ß-lactamase reporter. Here, we report a 60% reduction in sensing cost by reengineering the chimeric fusion protein biosensor to include a reporter system composed of either the full-length beta galactosidase (ß-gal), the alpha fragment of ß-gal (ß-gal-α), or a split alpha fragment of the ß-gal (split ß-gal-α). These biosensor constructs are deployed using E. coli XL1-Blue cell extract to (1) avoid the ß-gal background activity abundant in BL21 cell extract and (2) facilitate ß-gal complementation reporter activity to detect human thyroid receptor ligands. These results constitute a promising platform for high throughput screening and potentially the portable detection of human thyroid receptor ligands.

Interaction of ceftazidime and clindamycin with extracorporeal life support.

BACKGROUND: Ceftazidime and clindamycin are commonly prescribed to critically ill patients who require extracorporeal life support such as ECMO and CRRT. The effect of ECMO and CRRT on the disposition of ceftazidime and clindamycin is currently unknown. METHODS: Ceftazidime and clindamycin extraction were studied with ex vivo ECMO and CRRT circuits primed with human blood. The percent recovery of these drugs over time was calculated to determine the degree of interaction between these drugs and circuit components. RESULTS: Neither ceftazidime nor clindamycin exhibited measurable interactions with the ECMO circuit. In contrast, CRRT cleared 100% of ceftazidime from the experimental circuit within the first 2 h. Clearance of clindamycin from the CRRT circuit was slower, with about 20% removed after 6 h. CONCLUSION: Clindamycin and ceftazidime dosing adjustments are likely required in patients who are supported with CRRT, and future studies to quantify these adjustments should consider the pathophysiology of the patient in combination with the clearance due to CRRT. Dosing adjustments to account for adsorption to ECMO circuit components are likely unnecessary and should focus instead on the pathophysiology of the patient and changes in volume of distribution. These results will help improve the safety and efficacy of ceftazidime and clindamycin in patients requiring ECMO and CRRT.

"Just add small molecules" cell-free protein synthesis: Combining DNA template and cell extract preparation into a single fermentation.

Cell-free protein synthesis (CFPS) is a versatile biotechnology platform enabling a broad range of applications including clinical diagnostics, large-scale production of officinal therapeutics, small-scale on-demand production of personal magistral therapeutics, and exploratory research. The shelf stability and scalability of CFPS systems also have the potential to overcome cost and infrastructure challenges for distributing and using essential medical tests at home in both high- and low-income countries. However, CFPS systems are often more time-consuming and expensive to prepare than traditional in vivo systems, limiting their broader use. Much work has been done to lower CFPS costs by optimizing cell extract preparation, small molecule reagent recipes, and DNA template preparation. In order to further reduce reagent cost and preparation time, this work presents a CFPS system that does not require separately purified DNA template. Instead, a DNA plasmid encoding the recombinant protein is transformed into the cells used to make the extract, and the extract preparation process is modified to allow enough DNA to withstand homogenization-induced shearing. The finished extract contains sufficient levels of intact DNA plasmid for the CFPS system to operate. For a 10 mL scale CFPS system expressing recombinant sfGFP protein for a biosensor, this new system reduces reagent cost by more than half. This system is applied to a proof-of-concept glutamine sensor compatible with smartphone quantification to demonstrate its viability for further cost reduction and use in low-resource settings.