Tonsillar diffusion kinetics of amoxycillin after oral administration of 1 g to adults.

Although amoxycillin is widely used to treat pharyngo-tonsillitis, the kinetics of tonsillar diffusion have rarely been studied. The aim of this work was to study the kinetics of amoxycillin diffusion in the tonsils of adults, by measuring tonsillar concentrations 1.5, 3, 6 and 12 h after oral administration of 1 g of amoxycillin (Clamoxyl dispersible tablet, 1 g) relative to concomitant serum levels by using an HPLC method and a microbiological technique. At enrollment, the 20 patients were randomly divided into four groups of five, corresponding to the time intervals (1.5, 3, 6 or 12 h) between the third amoxycillin intake and the start of surgery. The results given by the two assay methods correlated well (r = 0.92-0.99). Amoxycillin showed excellent penetration into the tonsils, with both tonsillar and serum concentrations exceeding the MIC for most pathogens encountered in this setting (including Streptococcus pyogenes), even 12 h after repeated dosing with 1 g of amoxycillin.