Drug Disposition in Neonatal Göttingen Minipigs: Exploring Effects of Perinatal Asphyxia and Therapeutic Hypothermia.

Asphyxiated neonates often undergo therapeutic hypothermia (TH) to reduce morbidity and mortality. Since both perinatal asphyxia (PA) and TH influence physiology, altered pharmacokinetics (PK) and pharmacodynamics (PD) are expected. Given that TH is the standard of care for PA with moderate to severe hypoxic-ischemic encephalopathy, disentangling the effect of PA versus TH on PK/PD is not possible in clinical settings. However, animal models can provide insights into this matter. The (neonatal) Göttingen Minipig, the recommended strain for nonclinical drug development, was selected as translational model. Four drugs-midazolam (MDZ), fentanyl (FNT), phenobarbital (PHB), and topiramate (TPM)-were intravenously administered under four conditions: control (C), therapeutic hypothermia (TH), hypoxia (H), and hypoxia plus TH (H+TH). Each group included six healthy male neonatal Göttingen Minipigs anesthetized for 24 hours. Blood samples were drawn at 0 (predose) and 0.5, 2, 2.5, 3, 4, 4.5, 6, 8, 12, and 24 hours post drug administration. Drug plasma concentrations were determined using validated bioanalytical assays. The PK parameters were estimated through compartmental and noncompartmental PK analysis. The study showed a statistically significant decrease in FNT clearance (CL; 66% decrease), with an approximately threefold longer half-life (t1/2) in the TH group. The H+TH group showed a 17% reduction in FNT CL, with a 62% longer t1/2 compared with the C group; however, it was not statistically significant. Although not statistically significant, trends toward lower CL and longer t1/2 were observed in the TH and H+TH groups for MDZ and PHB. Additionally, TPM demonstrated a 28% decrease in CL in the H group compared with controls. SIGNIFICANCE STATEMENT: The overarching goal of this study using the neonatal Göttingen Minipig model was to disentangle the effects of systemic hypoxia and TH on PK using four model drugs. Such insights can subsequently be used to inform and develop a physiologically based pharmacokinetic model, which is useful for drug exposure prediction in human neonates.

Global cross-sectional survey on neonatal pharmacologic sedation and analgesia practices and pain assessment tools: impact of the sociodemographic index (SDI).

BACKGROUND: There is variability in the use of sedatives and analgesics in neonatal intensive care units (NICUs). We aimed to investigate the use of analgesics and sedatives and the management of neonatal pain and distress. METHODS: This was a global, prospective, cross-sectional study. A survey was distributed May-November 2022. The primary outcome of this research was to compare results between countries depending on their socio-sanitary level using the sociodemographic index (SDI). We organized results based on geographical location. RESULTS: The survey collected 1304 responses, but we analyzed 924 responses after database cleaning. Responses from 98 different countries were analyzed. More than 60% of NICUs reported having an analgosedation guideline, and one-third of respondents used neonatal pain scales in more than 80% of neonates. We found differences in the management of sedation and analgesia between NICUs on different continents, but especially between countries with different SDIs. Countries with a higher SDI had greater availability of and adherence to analgosedation guidelines, as well as higher rates of analgosedation for painful or distressing procedures. Countries with different SDIs reported differences in analgosedation for neonatal intubation, invasive ventilation, and therapeutic hypothermia, among others. CONCLUSIONS: Socio-economic status of countries impacts on neonatal analgosedation management. IMPACT: There is significant variability in the pain management practices in neonates. There is a lack of knowledge related to how neonatal pain management practices differ between regions. Sociodemographic index is a key factor associated with differences in neonatal pain management practices across global regions.

Publication Recommendations to Report Laboratory Data of Neonates - a Modified Delphi Approach.

BACKGROUND: Clinical and analytical information on laboratory data of neonates in scientific publications is sparse and incomplete. Furthermore, interpreting neonatal laboratory data can be complex due to their time-dependent and developmental physiology, and paucity of well-established age-appropriate reference ranges for neonates. This study aims to develop publication recommendations to report laboratory data of neonates to enhance the quality of these data in research and clinical care. METHODS: A modified Delphi approach was used to develop recommendations in cooperation with the International Neonatal Consortium. A Core Group, including different stakeholders, was responsible for developing the recommendations, in collaboration with a Reflection Group, responsible for providing additional input. RESULTS: The recommendations were classified into three categories: 'Clinical Characteristics', 'Bio-analytical Information' and 'Data-analytical Information'. These were each divided into 'Core Data' (always to be reported) and 'Supplemental Considerations' (to be reported when considered relevant to the study). CONCLUSION: Our recommendations provide guidance on standardization of neonatal laboratory data in publications. This will enhance the comparison, replication, and application of study results in research initiatives and clinical practice. Furthermore, these recommendations also serve as foundational work to develop reference ranges for neonatal laboratory values by standardizing the quality of information needed for such efforts. IMPACT: Standardized reporting of neonatal laboratory data in scientific publications will enhance the comparison, replication, and application of study results in research initiatives and clinical practice, as well as improve reporting to regulatory agencies. To integrate multistakeholder perspectives, a modified Delphi approach was used to develop publication recommendations which strengthens the applicability of the recommendations. Implementation of standardization will likely improve the overall quality of neonatal clinical research and neonatal healthcare. In addition, these recommendations are foundational to develop reference ranges for neonatal laboratory values by standardizing the quality of information needed for such efforts.

Grading the level of evidence of neonatal pharmacotherapy: midazolam and phenobarbital as examples.

BACKGROUND: Many drugs are used off-label or unlicensed in neonates. This does not mean they are used without evidence or knowledge. We aimed to apply and evaluate the Grading and Assessment of Pharmacokinetic-Pharmacodynamic Studies (GAPPS) scoring system for the level of evidence of two commonly used anti-epileptic drugs. METHODS: Midazolam and phenobarbital as anti-epileptics were evaluated with a systematic literature search on neonatal pharmacokinetic (PK) and/or pharmacodynamic [PD, (amplitude-integrated) electroencephalography effect] studies. With the GAPPS system, two evaluators graded the current level of evidence. Inter-rater agreement was assessed for dosing evidence score (DES), quality of evidence (QoE), and strength of recommendation (REC). RESULTS: Seventy-two studies were included. DES scores 4 and 9 were most frequently used for PK, and scores 0 and 1 for PD. Inter-rater agreements on DES, QoE, and REC ranged from moderate to very good. A final REC was provided for all PK studies, but only for 25% (midazolam) and 33% (phenobarbital) of PD studies. CONCLUSIONS: There is a reasonable level of evidence concerning midazolam and phenobarbital PK in neonates, although using a predefined target without integrated PK/PD evaluation. Further research is needed on midazolam use in term neonates with therapeutic hypothermia, and phenobarbital treatment in preterms. IMPACT: There is a reasonable level of evidence concerning pharmacotherapy of midazolam and phenobarbital in neonates. Most evidence is however based on PK studies, using a predefined target level or concentration range without integrated, combined PK/PD evaluation. Using the GAPPS system, final strength of recommendation could be provided for all PK studies, but only for 25% (midazolam) to 33% (phenobarbital) of PD studies. Due to the limited PK observations of midazolam in term neonates with therapeutic hypothermia, and of phenobarbital in preterm neonates these subgroups can be identified for further research.

Pharmacovigilance of nephrotoxic drugs in neonates: the Pottel method for acute kidney injury detection in ELBW neonates.

BACKGROUND: Extremely low birth weight (ELBW) neonates (birth weight ≤ 1000 g) are at high risk to develop drug-induced acute kidney injury (AKI). However, we lack a pragmatic detection tool to capture their time-dependent (patho)physiologic serum creatinine (Scr) patterns. Pottel et al. suggested rescaling Scr by dividing Scr with the mean Scr value of the age- and sex-specific reference population. We explored if this Pottel method can detect drug-related nephrotoxicity in ELBW neonates. METHODS: A previously reported dataset on Scr changes in ELBW neonates exposed to ibuprofen, amikacin, or vancomycin was updated to calculate Pottel scores for every available Scr value in the first 28 postnatal days. We hereby used previously published postnatal age-specific 50th centile values in an ELBW population. Linear mixed models were applied, analyzing Pottel scores as response variable and continuous time (day), drug exposure, and interaction thereof in the explanatory model. RESULTS: Serum creatinine (n = 3231) observations in 201 ELBW neonates were collected. A statistically significant rise of Pottel scores was observed with ibuprofen starting from postnatal day 4. In addition, a cumulative effect of treatment with mean Pottel scores on day 0 of 1.020 and on day 3 during treatment of 1.106 (95% CI 1.068-1.145, p < 0.001) was observed, corrected for effect of antibiotics. Antibiotic administrations showed a small but statistically significant difference up to postnatal day 5. CONCLUSIONS: As rescaled Scr biomarker, the Pottel method showed a clear association with ibuprofen-exposed ELBW neonates, suggesting its applicability as a pragmatic bedside alternative tool to assess nephrotoxicity.

Patients and informal caregivers in the lead: a qualitative study on the experiences of patients, informal caregivers, and healthcare professionals with involvement in treatment, e-health and self-management programs.

BACKGROUND: A significant proportion of patients and informal caregivers favor an active role in decisions concerning their health. Simultaneously, governments aim to shift treatment from a professional care setting to a community setting, in light of an ageing population, a decreasing number of health workers and allocation of scarce resources. This transition of care solicits patients' and informal caregivers' ability to self-manage. Therefore, the Maastricht University Medical Centre + has established the Academy for Patients and Informal caregivers. The aim is to proactively and professionally support patients and their informal caregivers to enhance their self-management. For that, the Academy offers activities in three categories: (1) instruction of nursing techniques, (2) training of e-health competencies and (3) the provision of self-management programs. Both patients with an episodic care need, as well as patients and informal caregivers with chronic illness, are eligible to participate in the Academy's activities. However, little is known about the experience of these interventions from the perspective of patients, informal caregivers and healthcare professionals. METHODS: We conducted semi-structured interviews with 15 patients, 8 informal caregivers and 19 health care professionals who either participated in, referred to or received patients from the Academy. Topics revolved around self-management and the Quadruple aim, covering topics such as patient experiences, healthcare costs, health and well-being of the population and improving work life for health professionals. Data were analyzed using thematic analysis. RESULTS: Patients and caregivers experienced an increase in the ability to manage health needs independently, leading to increased mental well-being and self-efficacy. They felt recognized as partners in care, although managing illness needs came with its own burdens. Health care professionals indicated that they felt assured of the quality, uniformity and availability of activities due to its central organization, with instruction nurses finding greater meaning in their work. On the level of health care systems, participants in this study mentioned a decrease in use of formal healthcare, whilst enabling a more equitable division of care. CONCLUSION: Stakeholders' experiences with the Academy for Patients and Informal caregivers indicate that participation contributes to development of self-management, whilst also improving working conditions, reducing the appeal to formal care and advancing equity in healthcare. The burden for patients and informal caregivers is to be considered in future developments.

Current knowledge, challenges and innovations in developmental pharmacology: A combined conect4children Expert Group and European Society for Developmental, Perinatal and Paediatric Pharmacology White Paper.

Developmental pharmacology describes the impact of maturation on drug disposition (pharmacokinetics, PK) and drug effects (pharmacodynamics, PD) throughout the paediatric age range. This paper, written by a multidisciplinary group of experts, summarizes current knowledge, and provides suggestions to pharmaceutical companies, regulatory agencies and academicians on how to incorporate the latest knowledge regarding developmental pharmacology and innovative techniques into neonatal and paediatric drug development. Biological aspects of drug absorption, distribution, metabolism and excretion throughout development are summarized. Although this area made enormous progress during the last two decades, remaining knowledge gaps were identified. Minimal risk and burden designs allow for optimally informative but minimally invasive PK sampling, while concomitant profiling of drug metabolites may provide additional insight in the unique PK behaviour in children. Furthermore, developmental PD needs to be considered during drug development, which is illustrated by disease- and/or target organ-specific examples. Identifying and testing PD targets and effects in special populations, and application of age- and/or population-specific assessment tools are discussed. Drug development plans also need to incorporate innovative techniques such as preclinical models to study therapeutic strategies, and shift from sequential enrolment of subgroups, to more rational designs. To stimulate appropriate research plans, illustrations of specific PK/PD-related as well as drug safety-related challenges during drug development are provided. The suggestions made in this joint paper of the Innovative Medicines Initiative conect4children Expert group on Developmental Pharmacology and the European Society for Developmental, Perinatal and Paediatric Pharmacology, should facilitate all those involved in drug development.

Model-Based Approach for Optimizing Ceftobiprole Dosage in Pediatric Patients.

Ceftobiprole is an advanced-generation cephalosporin for intravenous administration with activity against Gram-positive and Gram-negative organisms. A population pharmacokinetic (PK) model characterizing the disposition of ceftobiprole in plasma using data from patients in three pediatric studies was developed. Model-based simulations were subsequently performed to assist in dose optimization for the treatment of pediatric patients with hospital-acquired or community-acquired pneumonia. The population PK data set comprised 518 ceftobiprole plasma concentrations from 107 patients from 0 (birth) to 17 years of age. Ceftobiprole PK was well described by a three-compartment model with linear elimination. Ceftobiprole clearance was modeled as a function of glomerular filtration rate; other PK parameters were scaled to body weight. The final population PK model provided a robust and reliable description of the PK of ceftobiprole in the pediatric study population. Model-based simulations using the final model suggested that a ceftobiprole dose of 15 mg/kg of body weight infused over 2 h and administered every 12 h in neonates and infants <3 months of age or every 8 h in older pediatric patients would result in a ceftobiprole exposure consistent with that in adults and good pharmacokinetic-pharmacodynamic target attainment. The dose should be reduced to 10 mg/kg every 12 h in neonates and infants <3 months of age who weigh <4 kg to avoid high exposures. Extended intervals and reduced doses may be required for pediatric patients older than 3 months of age with renal impairment.

Population pharmacokinetics of cefazolin in maternal and umbilical cord plasma, and simulated exposure in term neonates.

BACKGROUND: Intra-partum cefazolin is used to prevent group B Streptococcus (GBS) vertical transmission in mothers allergic to penicillin without a history of anaphylaxis. OBJECTIVES: To investigate the maternal cefazolin dose-exposure relationship and subsequent maternal and neonatal target attainment at delivery. METHODS: Data were obtained from 24 healthy, GBS-colonized pregnant women (20-41 years), undergoing vaginal delivery (gestational age ≥37 weeks). During labour, all women received a 2 g cefazolin IV infusion. Eight hours later, eight women received another 1 g in the event of delayed (>8 h) delivery. Next to maternal plasma concentrations (up to 10 per dosing interval, until delivery), venous and arterial umbilical cord concentrations were determined at delivery. Target attainment in maternal/neonatal plasma was set at 1 mg/L for 60% of the dosing interval (unbound cefazolin, worst-case clinical breakpoint). A population pharmacokinetic (popPK) model was built (NONMEM 7.4). ClinicalTrials.gov Identifier: NCT01295606. RESULTS: At delivery, maternal blood and arterial umbilical cord unbound cefazolin concentrations were >1 mg/L in 23/24 (95.8%) and 11/12 (91.7%), respectively. The popPK of cefazolin in pregnant women was described by a two-compartment model with first-order elimination. Two additional compartments described the venous and arterial umbilical cord concentration data. Cefazolin target attainment was adequate in the studied cohort, where delivery occurred no later than 6.5 h after either the first or the second dose. PopPK simulations showed adequate maternal and umbilical cord exposure for 12 h following the first dose. CONCLUSIONS: PopPK simulations showed that standard pre-delivery maternal cefazolin dosing provided adequate target attainment up to the time of delivery.

Population pharmacokinetics of propofol in neonates and infants: Gestational and postnatal age to determine clearance maturation.

AIMS: Develop a population pharmacokinetic model describing propofol pharmacokinetics in (pre)term neonates and infants, that can be used for precision dosing (e.g. during target-controlled infusion) of propofol in this population. METHODS: A nonlinear mixed effects pharmacokinetic analysis (Monolix 2018R2) was performed, based on a pooled study population in 107 (pre)term neonates and infants. RESULTS: In total, 836 blood samples were collected from 66 (pre)term neonates and 41 infants originating from 3 studies. Body weight (BW) of the pooled study population was 3.050 (0.580-11.440) kg, postmenstrual age (PMA) was 36.56 (27.00-43.00) weeks and postnatal age (PNA) was 1.14 (0-104.00) weeks (median and min-max range). A 3-compartment structural model was identified and the effect of BW was modelled using fixed allometric exponents. Elimination clearance maturation was modelled accounting for the maturational effect on elimination clearance until birth (by gestational age [GA]) and postpartum (by PNA and GA). The extrapolated adult (70 kg) population propofol elimination clearance (1.64 L min-1 , estimated relative standard error = 6.02%) is in line with estimates from previous population pharmacokinetic studies. Empirical scaling of BW on the central distribution volume in function of PNA improved the model fit. CONCLUSIONS: It is recommended to describe elimination clearance maturation by GA and PNA instead of PMA on top of size effects when analyzing propofol pharmacokinetics in populations including preterm neonates. Changes in body composition in addition to weight changes or other physio-anatomical changes may explain the changes in central distribution volume. The developed model may serve as a prior for propofol dose finding and target-controlled infusion in (preterm) neonates.

Impact of enantiomer-specific changes in pharmacokinetics between infants and adults on the target concentration of racemic ketorolac: A pooled analysis.

AIMS: Ketorolac is a nonsteroidal anti-inflammatory racemic drug with analgesic effects only attributed to its S-enantiomer. The aim of this study is to quantify enantiomer-specific maturational pharmacokinetics (PK) of ketorolac and investigate if the contribution of both enantiomers to the total ketorolac concentration remains equal between infants and adults or if a change in target racemic concentration should be considered when applied to infants. METHODS: Data were pooled from 5 different studies in adults, children and infants, with 1020 plasma concentrations following single intravenous ketorolac administration. An allometry-based enantiomer-specific population PK model was developed with NONMEM 7.3. Simulations were performed in typical adults and infants to investigate differences in S- and R-ketorolac exposure. RESULTS: S- and R-ketorolac PK were best described with a 3- and a 2-compartment model, respectively. The allometry-based PK parameters accounted for changes between populations. No maturation function of ketorolac clearance could be identified. All model parameters were estimated with adequate precision (relative standard error <50%). Single dose simulations showed that a previously established analgesic concentration at half maximal effect in adults of 0.37 mg/L, had a mean S-ketorolac concentration of 0.057 mg/L, but a mean S-ketorolac concentration of 0.046 mg/L in infants. To match the effective adult S-ketorolac-concentration (0.057 mg/L) in typical infants, the EC50-racemic should be increased to 0.41 mg/L. CONCLUSION: Enantiomer-specific changes in ketorolac PK yield different concentrations and S- and R-ketorolac ratios between infants and adults at identical racemic concentrations. These PK findings should be considered when studies on maturational pharmacodynamics are considered.

A Population Pharmacokinetic Modeling and Simulation Study of Posaconazole Oral Suspension in Immunocompromised Pediatric Patients: A Short Communication.

BACKGROUND: Posaconazole oral suspension emerged as a promising candidate for prophylaxis of invasive fungal infections in immunocompromised children. Its pharmacodynamic advantages include a broad-spectrum activity and a favorable safety profile; however, they are overshadowed by its large pharmacokinetic (PK) variability, which might cause subtherapeutic exposure. The aim of this study was to develop a population (pop) PK model based on rich sampling data to better understand the PK of posaconazole oral suspension in pediatric patients. METHODS: Data were obtained from a prospective interventional study involving hospitalized pediatric patients with a hematologic malignancy and prophylactically treated with posaconazole oral suspension. After constructing the popPK model, the probability of target attainment (PTA; 100% T ≥ 0.7 mg/L) for prophylaxis under fixed, body weight-based, and body surface area-based dosing was evaluated using Monte Carlo simulation. RESULTS: Fourteen patients contributed 112 posaconazole plasma concentrations. The PK of posaconazole was adequately described by a 1-compartment model with lag time 2.71 hours [13%]; nonlinear bioavailability ED50 99.1 mg/m2 (fixed); first-order absorption rate constant 0.325 hour-1 [27%]; apparent volume of distribution 1150 L [34%]; and apparent clearance 15.4 L/h [24%] (∼70-kg individual). The bioavailability decreased in the presence of diarrhea and co-treatment with a proton pump inhibitor (PPI). The unexplained interindividual variability in posaconazole PK remained large. The PTA was <85%, irrespective of the simulated dosing strategy. Patients without diarrhea and not administered a PPI had the highest PTA (85% under the fixed 300-mg dosing 4 times per day). CONCLUSIONS: Therapeutic drug monitoring is recommended during prophylactic posaconazole therapy in immunocompromised pediatric patients. Large-scale comparative studies are needed to characterize the PK variability between different posaconazole formulations in this cohort.

Characterizing dynamics of serum creatinine and creatinine clearance in extremely low birth weight neonates during the first 6 weeks of life.

BACKGROUND: Characterizing the dynamics of serum creatinine concentrations (Scr) and associated creatinine clearance (CLcr) as a measure of kidney function in extremely low birth weight (≤ 1000 g; ELBW) neonates remains challenging. METHODS: We performed a retrospective study that included longitudinal Scr (enzymatic assay) data from 148 ELBW neonates up to 6 weeks after birth. Change of Scr and inter-individual variability was characterized with nonlinear mixed-effect modeling. Key covariates such as gestational age (GA), mode of delivery (MOD), and treatment with ibuprofen or inotropic agents were investigated. RESULTS: A total of 2814 Scr concentrations were analyzed. GA was associated with Scr at birth (higher with advancing GA), and GA and MOD showed an association with postnatal maturation of CLcr (faster clearance increase with advancing GA and after C-section). Small CLcr decrease (≤ 5%) was quantified during ibuprofen treatment. For a GA of 27 weeks, mean Scr (estimated CLcr) at birth was 0.61 mg/dl (0.23 ml/min), increasing to 0.87 mg/dl (0.27 ml/min) at day three, and decreasing to 0.36 mg/dl (0.67 ml/min) at day 42 after birth. CONCLUSIONS: We report the first mathematical model able to characterize Scr and CLcr in ELBW neonates during the first 6 weeks of life in a quantitative manner as a function of GA, MOD, and ibuprofen treatment. This model allows the derivation of GA-adjusted reference ranges for ELBW neonates and provides a rationale for normative Scr concentrations, and as such will help clinicians to further optimize monitoring and treatment decisions in this vulnerable patient population.

Covariates of amikacin disposition in a large pediatric oncology cohort.

OBJECTIVE: Amikacin pharmacokinetics (PK) in children display large variability due to maturational and disease-related covariates. The objective was to explore amikacin PK in a large pediatric oncology cohort, taking into account within-patient changes. MATERIALS AND METHODS: Clinical data and amikacin therapeutic drug monitoring (TDM) observations were collected retrospectively from children with an oncology diagnosis receiving amikacin during febrile neutropenia. Individual amikacin PK parameters were calculated using a 1-compartment model with instantaneous input and first-order output. This approach was selected based on a pragmatic study design using TDM from routine clinical care, with availability of 2 TDM samples per treatment episode. To explore covariates of clearance (Cl) and volume of distribution (Vd), linear mixed models were used, modelling a random effect for patient to account for clustering due to repeated measurements. RESULTS: Based on 188 amikacin treatment episodes in 114 patients, median (interquartile range) amikacin Cl was 1.37 (1.05; 2.46) L/h and Vd 7.98 (5.66; 12.73) L. Height and creatinemia were significant covariates for Cl (marginal R2 71.1%), while weight, height, and creatinemia determined Vd (marginal R2 59.5%). CONCLUSION: We described extensive variability of amikacin PK in a large cohort of pediatric oncology patients, including within-patient changes across treatment episodes. Maturational covariates and creatinemia determined amikacin Cl and Vd, while primary non-maturational covariates were not significant. Our observations, based on combined clinical and PK data in children with oncology diagnoses, can be useful to feed dosing software programs to improve drug exposure in special populations.

A sensitive liquid chromatography method for analysis of propofol in small volumes of neonatal blood.

WHAT IS KNOWN AND OBJECTIVE: Sampling volumes of blood from neonates is necessarily limited. However, most of the published propofol analysis assays require a relatively large blood sample volume (typically ≥0.5 mL). Therefore, the aim of the present study was to develop and validate a sensitive method requiring a smaller sample volume (0.2 mL) to fulfill clinically relevant research requirements. METHODS: Following simple protein precipitation and centrifugation, the supernatant was injected into the HPLC-fluorescence system and separated with a reverse phase column. Propofol and the internal standard (thymol) were detected and quantified using fluorescence at excitation and emission wavelengths of 270 nm and 310 nm, respectively. The method was validated with reference to the Food and Drug Administration (FDA) guidance for industry. Accuracy (CV, %) and precision (RSD, %) were evaluated at three quality control concentration levels (0.05, 0.5 and 5 µg/mL). RESULTS AND DISCUSSION: Calibration curves were linear in the range of 0.005-20 µg/mL. Intra- and interday accuracy (-4.4%-13.6%) and precision (0.2%-5.8%) for propofol were below 15%. The calculated LOD (limit of detection) and LLOQ (lower limit of quantification) were 0.0021 µg/mL and 0.0069 µg/mL, respectively. Propofol samples were stable for 4 months at -20°C after the sample preparation. This method was applied for analyzing blood samples from 41 neonates that received propofol, as part of a dose-finding study. The measured median (range) concentration was 0.14 (0.03-1.11) µg/mL, which was in the range of the calibration curve. The calculated median (range) propofol half-life of the gamma elimination phase was 10.4 (4.7-26.7) hours. WHAT IS NEW AND CONCLUSION: A minimal volume (0.2 mL) of blood from neonates is required for the determination of propofol with this method. The method can be used to support the quantification of propofol drug concentrations for pharmacokinetic studies in the neonatal population.

Nonlinear Transfer Entropy to Assess the Neurovascular Coupling in Premature Neonates.

In the adult brain, it is well known that increases in local neural activity trigger changes in regional blood flow and, thus, changes in cerebral energy metabolism. This regulation mechanism is called neurovascular coupling (NVC). It is not yet clear to what extent this mechanism is present in the premature brain. In this study, we explore the use of transfer entropy (TE) in order to compute the nonlinear coupling between changes in brain function, assessed by means of EEG, and changes in brain oxygenation, assessed by means of near-infrared spectroscopy (NIRS). In a previous study, we measured the coupling between both variables using a linear model to compute TE. The results indicated that changes in brain oxygenation were likely to precede changes in EEG activity. However, using a nonlinear and nonparametric approach to compute TE, the results indicate an opposite directionality of this coupling. The source of the different results provided by the linear and nonlinear TE is unclear and needs further research. In this study, we present the results from a cohort of 21 premature neonates. Results indicate that TE values computed using the nonlinear approach are able to discriminate between neonates with brain abnormalities and healthy neonates, indicating a less functional NVC in neonates with brain abnormalities.

Impact of Disease on Amikacin Pharmacokinetics and Dosing in Children.

BACKGROUND: Amikacin is widely used to treat severe Gram-negative bacterial infections. Its peak concentration in plasma is associated with treatment efficacy. Amikacin pharmacokinetics (PK) is influenced by disease conditions, in addition to other patient characteristics. In this retrospective study, we evaluated the impact of clinical characteristics and disease condition on amikacin PK in children with burn injuries and those with cancer. METHODS: Amikacin PK data from 66 children with burn injuries and 112 children with cancer were analyzed. A population PK model was developed using the nonlinear mixed-effects modeling approach. Models were developed using NONMEM 7.3 (ICON Development Solutions, LLC, Ellicott City, MD). Data processing and visualization was performed using R packages. RESULTS: The amikacin PK data were best described by a 2-compartment model. The parameters were estimated with mean values (95% confidence intervals) as follows: central volume of distribution (V1), 5.70 L (4.64-6.76 L); central clearance, 2.12 L/h (1.79-2.46 L/h); peripheral volume of distribution (V2), 4.79 L (2.36-7.22 L); and distribution clearance (Q), 0.71 L/h (0.25-1.16 L/h). The final model identified the disease condition as a significant covariate and indicated 55% (28%-82%) higher central clearance and 17% (1%-34%) higher V1 in burn patients compared with cancer patients. Volume of distribution was significantly influenced by age and body weight. Clearance was significantly influenced by age, body weight, and creatinine clearance. Using the final PK model, we developed a workflow for selecting optimal dosing strategies for 3 representative pediatric patient profiles. CONCLUSIONS: Disease condition was significant in influencing amikacin PK in children. To reach the same target concentrations (64 mg/L peak concentration) with a daily-dose plan, burn patients need higher doses than cancer patients. Future investigations are needed to explore the impact of other diseases on amikacin disposition in children, and to prospectively validate the proposed dosing strategy.

Dose rationale and pharmacokinetics of dexmedetomidine in mechanically ventilated new-borns: impact of design optimisation.

PURPOSE: There is a need for alternative analgosedatives such as dexmedetomidine in neonates. Given the ethical and practical difficulties, protocol design for clinical trials in neonates should be carefully considered before implementation. Our objective was to identify a protocol design suitable for subsequent evaluation of the dosing requirements for dexmedetomidine in mechanically ventilated neonates. METHODS: A published paediatric pharmacokinetic model was used to derive the dosing regimen for dexmedetomidine in a first-in-neonate study. Optimality criteria were applied to optimise the blood sampling schedule. The impact of sampling schedule optimisation on model parameter estimation was assessed by simulation and re-estimation procedures for different simulation scenarios. The optimised schedule was then implemented in a neonatal pilot study. RESULTS: Parameter estimates were more precise and similarly accurate in the optimised scenarios, as compared to empirical sampling (normalised root mean square error: 1673.1% vs. 13,229.4% and relative error: 46.4% vs. 9.1%). Most importantly, protocol deviations from the optimal design still allowed reasonable parameter estimation. Data analysis from the pilot group (n = 6) confirmed the adequacy of the optimised trial protocol. Dexmedetomidine pharmacokinetics in term neonates was scaled using allometry and maturation, but results showed a 20% higher clearance in this population compared to initial estimates obtained by extrapolation from a slightly older paediatric population. Clearance for a typical neonate, with a post-menstrual age (PMA) of 40 weeks and weight 3.4 kg, was 2.92 L/h. Extension of the study with 11 additional subjects showed a further increased clearance in pre-term subjects with lower PMA. CONCLUSIONS: The use of optimal design in conjunction with simulation scenarios improved the accuracy and precision of the estimates of the parameters of interest, taking into account protocol deviations, which are often unavoidable in this event-prone population.

Cerebral autoregulation and activity after propofol for endotracheal intubation in preterm neonates.

BACKGROUND: Despite increasing use of propofol in neonates, observations on cerebral effects are limited. AIM: To investigate cerebral autoregulation (CAR) and activity after propofol for endotracheal intubation in preterm neonates. METHODS: Twenty-two neonates received propofol before intubation as part of a published dose-finding study. Mean arterial blood pressure (MABP), near-infrared spectroscopy-derived cerebral oxygenation (rScO2), and amplitude-integrated electroencephalography (aEEG) were analyzed until 180 min after propofol. CAR was expressed as transfer function (TF) gain, indicating % change in rScO2 per 1 mmHg change in MABP. Values exceeding mean TF gain + 2 standard deviations (SD) defined impaired CAR. RESULTS: After intubation with a median propofol dose of 1 (0.5-4.5) mg/kg, rScO2 remained stable during decreasing MABP. Mean (±SD) TF gain was 0.8 (±0.3)%/mmHg. Impaired CAR was identified in 1 and 5 patient(s) during drug-related hypotension and normal to raised MABP, respectively. Suppressed aEEG was observed up to 60 min after propofol. CONCLUSIONS: Drug-related hypotension and decreased cerebral activity after intubation with low propofol doses in preterm neonates were observed, without evidence of cerebral ischemic hypoxia. CAR remained intact during drug-related hypotension in 95.5% of patients. Cerebral monitoring including CAR clarifies the cerebral impact of MABP fluctuations.