Comparison of Azithromycin Pharmacokinetics following Single Oral Doses of Extended-Release and Immediate-Release Formulations in Children with Acute Otitis Media

An azithromycin extended-release (ER) oral suspension was developed to improve the gastrointestinal tolerability profile without substantially compromising systemic exposure. A single dose of 30 mg/kg azithromycin immediate-release (IR) oral suspension has been used in children to treat acute otitis media (AOM). This study was conducted to compare the pharmacokinetics of a 60-mg/kg azithromycin ER single dose with a 30-mg/kg azithromycin IR single dose in children with AOM aged 6 months to 6 years (n = 19 per treatment). Serum samples were collected at 1, 2, 3, 4, 8, 24, 48, and 72 h after dosing. The area under the curve from time zero to 72 h postdosing (AUC(0-72)) was calculated based on a noncompartmental method. One-way analysis of variance (ANOVA) was used to compare exposure parameters (e.g., AUC(0-72) and peak concentration) as well as concentrations at each time point. The adjusted geometric mean ratio of the ER/IR AUC(0-72) was 157.98% (90% confidence interval [CI], 98.87%, 252.44%), which met the predefined criterion of the lower boundary of the 90% CI of ≥ 80%. As expected, due to the slower-release profile of the ER formulation, the concentrations of the ER formulation during the first 3 h were lower than those of the IR formulation. After 3 h postdosing, the lower boundaries of the 90% CI for the ER/IR concentration ratios were greater than 100%. These results indicated that a 60-mg/kg single dose of ER azithromycin provides similar or greater systemic exposure in children than the 30-mg/kg single dose of IR azithromycin.