Amoxicillin and clavulanic acid concentrations in gingival crevicular fluid

Abstract The β-lactams are bactericidal antibiotics, but some of them may be inactivated by bacterial β-lactamases which destroy the β-lactam ring. The inactivation of amoxicilhn by β-Iactamases of gram negative anaerobic bacteria can be circumvented by the addition of clavulanic acid, a β-lactamases inhibitor. Thus, most of these bacteria are susceptible to this combination. The aim of this study was to investigate the concentrations of amoxicillin and clavulanic acid in gingival crevicular fluid (GCF). These concentrations were measured in 20 patients with rapidly progressive periodontitis 1 h after a dose of 500 mg (1 tablet Augmentin®) on day 0 and 1 h after the 10th intake on day 3. For the sampling of GCF, Periopapers® were introduced in 16 gingival sites per subject and time. The GCF volumes collected were estimated using the Periotron 6000®. A high performance liquid chromatography method has been developed for the determination of amoxicillin and clavulanic acid in microsamples (1 to 10 μl) of GCF. The concentrations of amoxicillin and clavulanic acid were respectively, 14.05 μg ml^-1 and 0.40 μg ml^-1 at day 0.13.93 μg ml^-1 and 0.37 μg ml^-1 at day 3. Effective levels of amoxicillin and clavulanic acid, well above the minimal inhibitory concentrations of some susceptible periodontal anaerobes (P. intermedia) involved in destructive periodontal diseases, are achieved following the multiple administration of amoxicillin combined with clavulanic acid.