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Multiexponential elimination of gentamicin. A kinetic study during development
Insights
Gentamicin disposition varies significantly with age. Newborns exhibit prolonged gentamicin elimination and altered tissue distribution compared to older infants and children, highlighting age-dependent pharmacokinetics.
Area of Science:
- Pharmacology
- Pediatric Medicine
- Drug Metabolism
Background:
- Gentamicin is a crucial antibiotic for treating bacterial infections in neonates and children.
- Understanding gentamicin's pharmacokinetic profile is essential for optimizing dosing and minimizing toxicity.
- Limited data exists on the long-term disposition of gentamicin in premature newborns.
Purpose of the Study:
- To investigate the long-term disposition and pharmacokinetic parameters of gentamicin in premature newborns and compare them with older infants and children.
- To elucidate age-dependent differences in gentamicin tissue distribution and excretion.
Main Methods:
- Long-term pharmacokinetic study of gentamicin (up to 100-240 hours).
- Inclusion of 13 premature newborns (mean gestational age 33 weeks) and 7 infants/children (1 month to 8 years).
- Data analysis using bi- or triexponential curve fitting to determine pharmacokinetic parameters.
Main Results:
- Gentamicin terminal half-lives averaged 51 hours in newborns and 37 hours in infants/children.
- Newborns demonstrated significantly lower body clearance, central compartment volume, and steady-state volume of distribution compared to older subjects.
- The ratio of gentamicin in tissue to total body at steady state was lower in newborns (0.4) versus older children (0.52).
Conclusions:
- This study provides pharmacokinetic evidence of age-dependent gentamicin tissue distribution and excretion.
- Significant differences in gentamicin disposition exist between premature newborns and older pediatric populations.
- Findings underscore the importance of considering developmental stage in gentamicin therapy for pediatric patients.
Abstract:
The long-term disposition of gentamicin (up to 100-240 h) was studied in 13 premature newborns (33 weeks mean gestational age) and in 7 infants and children (1 month to 8 years). The data fitted bi- or triexponential curves with terminal half-lives averaging 51 and 37 h. Newborns showed lower values of body clearance, central compartment and steady state volumes of distribution than infants and children (respectively, 12.8 vs. 50.4 ml/min/1.73 m2, 9.03 vs. 17.5 liters/1.73 m2, and 15.7 vs. 35.5 liters/1.73 m2). The ratio between the amount of gentamicin predicted at steady state in the tissue compartment and in the total body was also significantly lower in newborns than in the older group (0.4 vs. 0.52). These data provide pharmacokinetic demonstration of an age dependence in gentamicin tissue distribution and excretion during the early stages of human development.