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Pharmacokinetics of a new macrolide, roxithromycin, in infants and children
F M Demotes-Mainard1, G A Vinçon, H C Albin
1Department of Clinical Pharmacology, Hôpital Pellegrin, Bordeaux, France.
Insights
Roxithromycin pharmacokinetics in children showed age-independent absorption and elimination. Repeated doses did not lead to accumulation, supporting a potential two-dose regimen for respiratory tract infections.
Area of Science:
- Pharmacology
- Pediatric Medicine
- Infectious Diseases
Background:
- Roxithromycin is a macrolide antibiotic used for bacterial infections.
- Understanding its pharmacokinetics in pediatric populations is crucial for effective dosing.
- Respiratory tract infections are common in infants and children.
Purpose of the Study:
- To investigate the pharmacokinetics of roxithromycin in infants and children.
- To determine if age influences roxithromycin's absorption, distribution, metabolism, and excretion.
- To assess drug accumulation and plasma concentrations relative to minimum inhibitory concentrations (MICs).
Main Methods:
- Oral administration of 2.5 mg/kg roxithromycin every 12 hours for 6 days.
- Study involved 18 pediatric subjects divided into three age groups ( <18 months, <5 years, <13 years).
- Plasma concentrations were measured to determine pharmacokinetic parameters like half-life and Cmax.
Main Results:
- Elimination plasma half-life averaged around 20 hours across all age groups.
- Maximum concentration (Cmax) was reached within 1-2 hours post-dose.
- Pharmacokinetic parameters were not significantly different between age groups, indicating age independence.
- No significant drug accumulation was observed after repeated dosing.
- Plasma concentrations remained above MICs for common respiratory pathogens for 12 hours.
Conclusions:
- Roxithromycin pharmacokinetics in pediatric patients appear to be age-independent.
- A twice-daily dosing regimen of 2.5 mg/kg roxithromycin is potentially effective for treating respiratory tract infections in infants and children.
- Further clinical studies may validate this dosing regimen.
Abstract:
The pharmacokinetics of roxithromycin was investigated after oral administration of 2.5 mg/kg doses given 12 hours apart during 6 days in infants and children. These 18 subjects suffering from a respiratory tract infection were divided into three age groups: group I less than 18 months, group II less than 5 years, group III less than 13 years. At day 6, the elimination plasma half-life had an average value (mean +/- SD) of 19.8 +/- 9.7 h (group I), 21.0 +/- 9.4 h (group II) and 20.8 +/- 6.9 h (group III), respectively. The maximum concentration of roxithromycin (Cmax) was attained between 1 and 2 hours after dosing with mean values of 10.1 +/- 3.0 mg/l (group I), 8.7 +/- 4.9 mg/l (group II), 8.8 +/- 7.0 mg/l (group III). All the calculated pharmacokinetic parameters did not significantly differ from one group to another. The kinetics of roxithromycin in infants and children seemed to be age independent and showed no accumulation after repeated doses. During 12 hours, the plasma concentrations were above MIC of microorganisms generally present in respiratory tract infections. Two daily doses of 2.5 mg/kg of roxithromycin 12 hours apart may be proposed in infants and children.