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Theophylline metabolism during the first month of life and development
Insights
Theophylline metabolism differs significantly with age. Newborns methylate theophylline to caffeine, while older individuals demethylate it to 3-methylxanthine, impacting clearance.
Area of Science:
- Pharmacology
- Drug Metabolism
- Pediatric Medicine
Background:
- Theophylline is a widely used medication, particularly in neonates for respiratory conditions.
- Understanding its metabolic pathways is crucial for optimizing therapeutic use and managing potential toxicity.
- Age-dependent differences in drug metabolism are well-documented but require specific investigation for theophylline.
Purpose of the Study:
- To elucidate the metabolic pathways of theophylline (T) in different age groups, from newborns to adults.
- To identify age-specific metabolites of theophylline and their excretion patterns.
- To compare the renal and body clearance of theophylline and its metabolites across pediatric and adult populations.
Main Methods:
- Intravenous administration of theophylline (T) to 12 newborns, 1 infant, 6 children, and 3 adults.
- Assay of blood and urine samples using high-pressure liquid chromatography (HPLC) to quantify T, caffeine (C), and metabolites.
- Analysis of metabolic pathways including methylation and demethylation.
Main Results:
- Confirmed methylation of theophylline to caffeine (C) exclusively in newborn infants.
- Identified demethylation of theophylline to 3-methylxanthine in infants, children, and adults, but not in newborns.
- Neonates primarily excreted theophylline, 1-methyluric acid, and 1,3-dimethyluric acid; children excreted a higher fraction of methyluric acids than adults.
Conclusions:
- Theophylline metabolism exhibits significant age-dependent variations, with distinct pathways predominating in neonates versus older individuals.
- Methylation to caffeine is a key pathway in newborns, while demethylation becomes prominent in older subjects.
- Age influences the clearance and metabolic profile of theophylline, necessitating age-specific dosing and monitoring strategies.
Abstract:
The metabolic pathway of theophylline (T) was studied in 12 newborns, one young infant, six children, and three adult volunteers. T was injected IV, and blood and urine samples were assayed for T, caffeine (C), and their metabolites by a high-pressure liquid chromatography technique. We confirmed the methylation of T to C in newborn infants but not in older subjects. Demethylation of T to 3-methylxanthine was found in the young infant, in children, and in adults, but not in newborns. The major products excreted by neonates were T, 1-methyluric acid, and 1,3-dimethyluric acid. Children excreted a larger fraction of methyluric acids than adults. Renal and body clearance of T and C are reported and discussed in relation to the age.