Improved tonsillar disposition of azithromycin following a 3-day oral treatment with 20 mg kg(-1) in paediatric patients.

The present study was performed in order to compare azithromycin concentrations in tonsils of paediatric patients treated with different dose regimens of this antibiotic. Sixty-four children, scheduled to undergo surgical removal of tonsils, were treated with azithromycin 10 or 20 mgkg(-1) daily as oral suspension for 3 days. Samples of blood and tonsil were collected during surgery at days 0.5, 2.5, 4.5, 6.5 or 8.5 after the last dose. Azithromycin concentrations were measured by reversed phase high-performance liquid chromatography. In patients treated with 10 mgkg(-1), the highest concentrations of azithromycin were detected in plasma and tonsils at day 0.5 and 2.5, respectively. Consistent drug levels could be measured in tonsils up to 8.5 days. After administration of 20 mgkg(-1), azithromycin tonsillar concentrations were higher than those obtained with 10 mgkg(-1) up to day 6.5, whereas plasma levels did not differ significantly. The present results indicate that an improved tonsillar distribution of azithromycin can be achieved when this antibiotic is administered for 3 days at doses higher than 10 mgkg(-1) daily. These findings give pharmacokinetic support to the suggestion that increments of azithromycin dosing might ensure enhanced therapeutic levels at infective sites of the upper respiratory tract.