A Master Protocol Template for Pediatric ARDS Studies.

BACKGROUND: Pediatric ARDS is associated with significant morbidity and mortality. High-quality data from clinical trials in children are limited due to numerous barriers to their design and execution. Here we describe the collaborative development of a master protocol as a tool to address some of these barriers and support the conduct of pediatric ARDS studies. METHODS: Using PubMed, we performed a literature search of randomized controlled trials (RCTs) in pediatric ARDS to characterize the current state and evaluate potential benefit of harmonized master protocols. We used a multi-stakeholder, collaborative, and team science-oriented process to develop a master protocol template with links to common data elements (CDEs) for pediatric ARDS trials. RESULTS: We identified 11 RCTs that enrolled between 14-200 total subjects per trial. Interventions included mechanical ventilation, prone positioning, corticosteroids, and surfactant. Studies displayed significant heterogeneity in ARDS definition, design, inclusion and exclusion criteria, and reported outcomes. Mortality was reported in 91% of trials and ventilator-free days in 73%. The trial heterogeneity made pooled analysis unfeasible. These findings underscore the need for a method to facilitate combined analysis of future trials through standardization of trial elements. As a potential solution, we developed a master protocol, iteratively revised with input from a multidisciplinary panel of experts and organized into 3 categories: instructions and general information, templated language, and a series of text options of common pediatric ARDS trial scenarios. Finally, we linked master protocol sections to relevant CDEs previously defined for pediatric ARDS and captured in a series of electronic case report forms. CONCLUSIONS: The majority of pediatric ARDS trials identified were small and heterogeneous in study design and outcome reporting. Using a master protocol template for pediatric ARDS trials with CDEs would support combining and comparing pediatric ARDS trial findings and increase the knowledge base.

Opportunistic dried blood spot sampling validates and optimizes a pediatric population pharmacokinetic model of metronidazole.

Pharmacokinetic models rarely undergo external validation in vulnerable populations such as critically ill infants, thereby limiting the accuracy, efficacy, and safety of model-informed dosing in real-world settings. Here, we describe an opportunistic approach using dried blood spots (DBS) to evaluate a population pharmacokinetic model of metronidazole in critically ill preterm infants of gestational age (GA) ≤31 weeks from the Metronidazole Pharmacokinetics in Premature Infants (PTN_METRO, NCT01222585) study. First, we used linear correlation to compare 42 paired DBS and plasma metronidazole concentrations from 21 preterm infants [mean (SD): post natal age 28.0 (21.7) days, GA 26.3 (2.4) weeks]. Using the resulting predictive equation, we estimated plasma metronidazole concentrations (ePlasma) from 399 DBS collected from 122 preterm and term infants [mean (SD): post natal age 16.7 (15.8) days, GA 31.4 (5.1) weeks] from the Antibiotic Safety in Infants with Complicated Intra-Abdominal Infections (SCAMP, NCT01994993) trial. When evaluating the PTN_METRO model using ePlasma from the SCAMP trial, we found that the model generally predicted ePlasma well in preterm infants with GA ≤31 weeks. When including ePlasma from term and preterm infants with GA >31 weeks, the model was optimized using a sigmoidal Emax maturation function of postmenstrual age on clearance and estimated the exponent of weight on volume of distribution. The optimized model supports existing dosing guidelines and adds new data to support a 6-hour dosing interval for infants with postmenstrual age >40 weeks. Using an opportunistic DBS to externally validate and optimize a metronidazole population pharmacokinetic model was feasible and useful in this vulnerable population.

Pharmacokinetics of Oral Vitamin D in Children with Obesity and Asthma.

BACKGROUND AND OBJECTIVE: Vitamin D insufficiency is common in several pediatric diseases including obesity and asthma. Little data exist describing the pharmacokinetics of oral vitamin D in children or the optimal dosing to achieve therapeutic 25(OH)D targets. Describe the pharmacokinetics of oral Vitamin D in children with asthma. METHODS: This was a multi-center, randomized, open-label, oral supplementation study to describe the pharmacokinetics of vitamin D in children aged 6-17 years who have asthma and were overweight/obese. Participants had a serum 25(OH)D concentration between 10 and < 30 ng/mL at baseline. In Part 1 of the study, we assessed four 16-week dosing regimens for their ability to achieve 25(OH)D concentrations ≥ 40 ng/mL. Using serial serum 25(OH)D sampling over 28 weeks, we created a population pharmacokinetic model and performed dosing simulations to achieve 25(OH)D concentrations ≥ 40 ng/mL. In Part 2, the optimal regimen chosen from Part 1 was compared (2:1) to a standard-of-care control dose (600 international units [IU] daily) over 16 weeks. A final population pharmacokinetic model using both parts was developed to perform dosing simulations and determine important co-variates in the pharmacokinetics of vitamin D. RESULTS: Based on empiric and simulation data, the daily dose of 8000 IU and a loading dose of 50,000 IU were chosen; this regimen raised 25(OH)D concentrations above 40 ng/mL in the majority of participants while avoiding concentrations > 100 ng/mL. A 50,000-IU loading dose led to faster achievement of 25(OH)D therapeutic concentrations (≥ 40 ng/mL). The estimated median (5th-95th percentiles) apparent clearance of vitamin D from the final population pharmacokinetic model was 0.181 (0.155-0.206) L/h. The body mass index z-score was a significant covariate on apparent clearance and was associated with a significantly decreased median half-life in 25(OH)D (body mass index z-score 1.00-1.99: 97.7 days, body mass index z-score 2.00-2.99: 65.9 days, body mass index z-score ≥ 3.00: 39.1 days, p < 0.001). CONCLUSIONS: Obesity impacts vitamin D clearance and the half-life, but serum concentrations > 40 ng/mL can be reached in most children using a loading dose of 50,000 IU followed by a daily dose of 8000 IU. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier number NCT03686150.