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Pharmacokinetics of Oral Vitamin D in Children with Obesity and Asthma
Jason E Lang1,2, Rodrigo Gonzalez Ramirez3, Stephen Balevic4,3
1Duke Children's Hospital and Health Center, Durham, NC, USA. jason.lang@duke.edu.
Insights
This study found that a loading dose of 50,000 IU followed by 8000 IU daily effectively raises vitamin D levels in children with asthma and obesity. Obesity significantly affects vitamin D levels, but this regimen achieves therapeutic targets.
Area of Science:
- Pediatric Endocrinology
- Pharmacokinetics
- Nutritional Science
Background:
- Vitamin D insufficiency is prevalent in pediatric conditions like asthma and obesity.
- Limited data exist on oral vitamin D pharmacokinetics and optimal dosing in children.
- Understanding vitamin D metabolism is crucial for managing associated health issues.
Purpose of the Study:
- To describe the pharmacokinetics of oral vitamin D in children with asthma and overweight/obesity.
- To determine optimal dosing regimens to achieve therapeutic serum 25(OH)D concentrations (≥ 40 ng/mL).
- To investigate the impact of covariates, such as obesity, on vitamin D pharmacokinetics.
Main Methods:
- A multi-center, randomized, open-label study involving children aged 6-17 years with asthma and overweight/obesity.
- Assessed four 16-week dosing regimens in Part 1, followed by population pharmacokinetic modeling.
- Part 2 compared the optimal regimen to standard-of-care, with a final model developed using data from both parts.
Main Results:
- A regimen of 8000 IU daily with a 50,000 IU loading dose successfully raised 25(OH)D concentrations above 40 ng/mL in most participants.
- The loading dose accelerated the achievement of therapeutic 25(OH)D levels.
- Body mass index z-score was a significant covariate, decreasing vitamin D half-life, particularly in severely obese children.
Conclusions:
- Obesity significantly influences vitamin D clearance and half-life in children with asthma.
- A specific loading and daily dosing regimen can achieve therapeutic vitamin D concentrations in this population.
- This provides a basis for optimizing vitamin D supplementation in pediatric asthma patients with obesity.
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.
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