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Absorption and bioavailability of oral erythromycin
British Journal of Clinical Pharmacology
|August 1, 1981
Summary
Erythromycin stearate tablets taken before meals (Regimen A) resulted in higher serum concentrations and more predictable absorption compared to erythromycin base capsules taken after meals (Regimen B). Regimen A demonstrated superior erythromycin bioavailability and absorption kinetics.
Area of Science:
- Pharmacokinetics
- Drug Absorption
- Clinical Pharmacology
Background:
- Erythromycin is a widely used antibiotic.
- Oral administration of erythromycin can lead to variable absorption.
- Understanding absorption kinetics is crucial for optimizing therapeutic efficacy.
Purpose of the Study:
- To compare the extent and rate of erythromycin absorption from two oral dosage regimens in healthy volunteers.
- To evaluate the impact of food intake timing on erythromycin bioavailability.
- To assess the predictability of serum concentrations based on absorption kinetics.
Main Methods:
- 24 healthy volunteers received two oral regimens of erythromycin (250 mg every 6 hours for 9 doses): Regimen A (stearate tablets 1 hour before meals) and Regimen B (base capsules 30 minutes after meals).
- Serum erythromycin concentrations were measured during the first and ninth dosing intervals.
- Key pharmacokinetic parameters including maximum serum concentrations, time to maximum concentration, lag time, and absolute bioavailability were determined.
Main Results:
- Regimen A yielded significantly higher maximum serum concentrations (median 2.7 mg/l at steady-state) compared to Regimen B (median 1.4 mg/l at steady-state).
- Absorption was faster and more predictable with Regimen A (median Tmax 118 min at steady-state) versus Regimen B (median Tmax 173 min at steady-state), with notably shorter lag times.
- Absolute bioavailability was higher for Regimen A (approx. 65% at steady-state) compared to Regimen B (approx. 40%).
Conclusions:
- Erythromycin stearate tablets administered before meals (Regimen A) offer superior absorption and bioavailability compared to erythromycin base capsules taken after meals (Regimen B).
- Variability in oral erythromycin absorption kinetics and bioavailability, not disposition kinetics, is the primary driver of intersubject variability in serum concentrations.
- Regimen A provides more predictable erythromycin serum concentrations, potentially leading to more consistent therapeutic outcomes.