The age-dependence of intestinal absorption using d-xylose as an example

Area of Science:

• Pediatric Gastroenterology
• Pharmacokinetics
• Nutritional Science

Background:

• D-xylose absorption is a key indicator of intestinal function.
• Understanding pediatric absorption kinetics is crucial for assessing gastrointestinal health in infants.
• Age-related physiological differences in infants can significantly impact drug and nutrient absorption.

Purpose of the Study:

• To investigate the age-dependent absorption kinetics of D-xylose in infants.
• To explore the relationship between D-xylose absorption parameters and infant age.
• To evaluate the role of gastrointestinal motility in D-xylose absorption in young infants.

Main Methods:

• Serum D-xylose concentrations were measured in 40 infants over 300 minutes after oral administration (0.5 g/kg).
• Absorption and elimination kinetic parameters (k1, k2) were calculated using a digital computer program.
• Metoclopramide was administered concurrently with D-xylose in some infants to assess the impact of gastrointestinal motility.

Main Results:

• Infants under 2 months showed lower maximal serum D-xylose concentrations and a larger volume of distribution compared to older infants.
• The rate constants for intestinal absorption (k1) and elimination (k2) were significantly lower in infants under 2 months.
• Time to maximal serum concentration was prolonged in younger infants; metoclopramide did not fully account for slower absorption, and saturation kinetics were suggested at higher D-xylose doses.

Conclusions:

• D-xylose absorption kinetics in infants are significantly influenced by age, particularly in the first two months of life.
• Slower gastrointestinal motility in young infants is not the sole reason for reduced D-xylose absorption.
• Further research into saturation kinetics of D-xylose absorption in infants is warranted.