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Pharmacokinetics of erythromycin ethylsuccinate and estolate in infants under 4 months of age
Insights
Erythromycin estolate shows higher serum concentrations and longer half-lives than ethylsuccinate in infants. This suggests different dosing intervals for these erythromycin suspensions in treating pediatric infections.
Area of Science:
- Pediatric Pharmacology
- Infectious Diseases
Background:
- Erythromycin is a key antibiotic for treating common infant infections.
- Understanding the pharmacokinetics of different erythromycin formulations is crucial for safe and effective treatment in young infants.
Purpose of the Study:
- To compare the pharmacokinetics of erythromycin estolate and ethylsuccinate suspensions in infants under 4 months.
- To establish optimal dosing regimens for each formulation in this vulnerable population.
Main Methods:
- Pharmacokinetic analysis of erythromycin estolate and ethylsuccinate after single and steady-state doses.
- Measurement of peak serum concentrations, absorption, and elimination half-lives.
- Comparison of area under the curve (AUC) for both formulations.
Main Results:
- Erythromycin estolate demonstrated higher peak serum concentrations and longer absorption and elimination half-lives compared to ethylsuccinate.
- Peak concentrations for estolate occurred at 3 hours, versus 1 hour for ethylsuccinate.
- The AUC for estolate was approximately three times greater than that for ethylsuccinate.
Conclusions:
- Erythromycin estolate requires less frequent dosing (8- or 12-h intervals) due to its pharmacokinetic profile.
- Erythromycin ethylsuccinate is best administered every 6 hours.
- These findings support tailored dosing strategies for erythromycin suspensions in young infants based on formulation.
Abstract:
We studied the pharmacokinetics of erythromycin estolate and ethylsuccinate suspensions in infants under 4 months of age who were being treated for chlamydial infections or pertussis. We conducted our studies after the initial dose of 10 mg/kg and subsequently during steady-state treatment. The estolate preparation resulted in higher peak concentrations in sera, and its absorption and elimination half-lives were longer. Peak concentrations occurred 3 h after a dose with the estolate preparation and 1 h after a dose with the ethylsuccinate preparation. The area under the curve for the estolate preparation was about three times greater than that for the ethylsuccinate preparation. Based on these findings, we recommend that erythromycin estolate suspensions be given to young infants at 8- or 12-h intervals (30 mg/kg per day in three divided doses or 20 mg/kg per day in two divided doses) and that erythromycin ethylsuccinate is best given at 6-h intervals (40 mg/kg per day in four divided doses).