Pharmacokinetics of intravenously administered azithromycin in pediatric patients

Background: The objective of this study was to characterize the pharmacokinetics and tolerance of a single intravenous (IV) azithromycin dose in children. Methods: Subjects were stratified into 4 age groups: 0.5-2 years; >2->6 years; 6-<12 years; and 12-<16 years. Each subject received a single 10 mg/kg dose (500 mg maximum) infused in 1 hour. Serial venous blood samples were obtained for a 168-hour period, and laboratory safety evaluations were performed immediately preceding azithromycin administration and at the conclusion of the study. Serum azithromycin concentrations were quantified with a validated high performance liquid chromatography method with mass spectrometric detection. Pharmacokinetic indices were calculated for each subject by noncompartmental techniques. Results: Thirty-two subjects (6.7 +/- 5.0 years, 11 boys) participated. Mean serum concentration-time data were comparable for the 4 age groups. For all subjects with evaluable data, the mean area under the curve from 0 to 72 hours (AUC(0-72)) was 8.2 mug (.) h/mL (n = 26), the maximum concentration (C(max)) was 2.4 mug/mL and the elimination half-life (t(1/2)) was 65.2 hours (n = 25). The AUC(0-72) and C(max) were not associated with age. The dose was well-tolerated with no serious adverse events. Conclusion: The disposition of azithromycin after a single 10 mg/kg IV dose (maximum labeled adult dose of 500 mg) is comparable in pediatric patients between 0.5 and 16 years of age. These pharmacokinetic data can be used to guide dose selection for future therapeutic trials of IV azithromycin in pediatric patients.