Dataset Information

The Oral Bioavailability and Metabolism of Midazolam in Stable Critically Ill Children: A Pharmacokinetic Microtracing Study.

ABSTRACT: Midazolam is metabolized by the developmentally regulated intestinal and hepatic drug-metabolizing enzyme cytochrome P450 (CYP) 3A4/5. It is frequently administered orally to children, yet knowledge is lacking on the oral bioavailability in term neonates up until 1 year of age. Furthermore, the dispositions of the major metabolites 1-OH-midazolam (OHM) and 1-OH-midazolam-glucuronide (OHMG) after oral administration are largely unknown for the entire pediatric age span. We aimed to fill these knowledge gaps with a pediatric [¹⁴ C]midazolam microtracer population pharmacokinetic study. Forty-six stable, critically ill children (median age 9.8 (range 0.3-276.4) weeks) received a single oral [¹⁴ C]midazolam microtracer (58 (40-67) Bq/kg) when they received a therapeutic continuous intravenous midazolam infusion and had an arterial line in place enabling blood sampling. For midazolam, in a one-compartment model, bodyweight was a significant predictor for clearance (0.98 L/hour) and volume of distribution (8.7 L) (values for a typical individual of 5 kg). The typical oral bioavailability in the population was 66% (range 25-85%). The exposures of OHM and OHMG were highest for the youngest age groups and significantly decreased with postnatal age. The oral bioavailability of midazolam, largely reflective of intestinal and hepatic CYP3A activity, was on average lower than the reported 49-92% for preterm neonates, and higher than the reported 21% for children> 1 year of age and 30% for adults. As midazolam oral bioavailability varied widely, systemic exposure of other CYP3A-substrate drugs after oral dosing in this population may also be unpredictable, with risk of therapy failure or toxicity.

SUBMITTER: van Groen BD

PROVIDER: S-EPMC7818442 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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The Oral Bioavailability and Metabolism of Midazolam in Stable Critically Ill Children: A Pharmacokinetic Microtracing Study.

van Groen Bianca D BD Krekels Elke H J EHJ Mooij Miriam G MG van Duijn Esther E Vaes Wouter H J WHJ Windhorst Albert D AD van Rosmalen Joost J Hartman Stan J F SJF Hendrikse N Harry NH Koch Birgit C P BCP Allegaert Karel K Tibboel Dick D Knibbe Catherijne A J CAJ de Wildt Saskia N SN

Clinical pharmacology and therapeutics 20200628 1

Midazolam is metabolized by the developmentally regulated intestinal and hepatic drug-metabolizing enzyme cytochrome P450 (CYP) 3A4/5. It is frequently administered orally to children, yet knowledge is lacking on the oral bioavailability in term neonates up until 1 year of age. Furthermore, the dispositions of the major metabolites 1-OH-midazolam (OHM) and 1-OH-midazolam-glucuronide (OHMG) after oral administration are largely unknown for the entire pediatric age span. We aimed to fill these kno ...[more]

PMID: 32403162

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Project description:ObjectivesTo develop a pharmacokinetic-pharmacogenomic population model of midazolam in critically ill children with primary respiratory failure.DesignProspective pharmacokinetic-pharmacogenomic observational study.SettingThirteen PICUs across the United States.PatientsPediatric subjects mechanically ventilated for acute respiratory failure, weight greater than or equal to 7 kg, receiving morphine and/or midazolam continuous infusions.InterventionsSerial blood sampling for drug quantification and a single blood collection for genomic evaluation.Measurements and main resultsConcentrations of midazolam, the 1' (1`-hydroxymidazolam metabolite) and 4' (4`-hydroxymidazolam metabolite) hydroxyl, and the 1' and 4' glucuronide metabolites were measured. Subjects were genotyped using the Illumina HumanOmniExpress genome-wide single nucleotide polymorphism chip. Nonlinear mixed effects modeling was performed to develop the pharmacokinetic-pharmacogenomic model. Body weight, age, hepatic and renal functions, and the UGT2B7 rs62298861 polymorphism are relevant predictors of midazolam pharmacokinetic variables. The estimated midazolam clearance was 0.61 L/min/70kg. Time to reach 50% complete mature midazolam and 1`-hydroxymidazolam metabolite/4`-hydroxymidazolam metabolite clearances was 1.0 and 0.97 years postmenstrual age. The final model suggested a decrease in midazolam clearance with increase in alanine transaminase and a lower clearance of the glucuronide metabolites with a renal dysfunction. In the pharmacogenomic analysis, rs62298861 and rs28365062 in the UGT2B7 gene were in high linkage disequilibrium. Minor alleles were associated with a higher 1`-hydroxymidazolam metabolite clearance in Caucasians. In the pharmacokinetic-pharmacogenomic model, clearance was expected to increase by 10% in heterozygous and 20% in homozygous for the minor allele with respect to homozygous for the major allele.ConclusionsThis work leveraged available knowledge on nonheritable and heritable factors affecting midazolam pharmacokinetic in pediatric subjects with primary respiratory failure requiring mechanical ventilation, providing the basis for a future implementation of an individual-based approach to sedation.

Project description:ObjectiveThe objective of this study was to characterize the population pharmacokinetics of fentanyl and identify factors that contribute to exposure variability in critically ill pediatric patients.MethodsWe conducted a single-center, retrospective cohort study using electronic record data and remnant blood samples in the setting of a mixed medical/surgical intensive care unit (ICU) at a quaternary children's hospital. Children with a predicted ICU length of stay of at least 3 days and presence of an indwelling central venous or arterial line were included. Serum fentanyl measurements were performed for 278 unique remnant samples from 66 patients. Both one- and two-compartment models were evaluated to describe fentanyl disposition. Covariates were introduced into the model in a forward/backward, stepwise approach and included age, sex, race, weight, cytochrome P450 (CYP) 3A5 genotype, and the presence of CYP3A4 or CYP3A5 inducers or inhibitors. Simulations were performed using the successful model to depict the influence of inducers on fentanyl concentrations.ResultsA two-compartment base model best described the data. There was good agreement between observed and predicted concentrations in the final model. The typical fentanyl clearance for 70 kg (reference weight) and 20.1 kg (median weight) patients were 34.6 and 13.6 L/h, respectively. The magnitude of the unexplained random inter-individual variability was high for both clearance (60.7%) and apparent volume of the central compartment (V1) (107.2%). Coadministration of the known CYP3A4/5 inducers fosphenytoin and/or phenobarbital was associated with significantly increased fentanyl clearance. Simulations demonstrate that the effect of inducer administration was most pronounced following discontinuation of a fentanyl infusion.ConclusionsIn this study we show the feasibility and utility of using electronic record data and remnant blood samples to successfully construct population pharmacokinetic models for a heterogeneous cohort of critically ill children. A clinically relevant effect of concomitant CYP3A4/5 inducers was identified. Scaling this population pharmacokinetic approach is necessary to craft precision approaches to fentanyl administration for critically ill children.

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Dataset Information

The Oral Bioavailability and Metabolism of Midazolam in Stable Critically Ill Children: A Pharmacokinetic Microtracing Study.

Publications

The Oral Bioavailability and Metabolism of Midazolam in Stable Critically Ill Children: A Pharmacokinetic Microtracing Study.

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