Concentrations of tinidazole in gingival crevicular fluid and plasma in dogs after multiple dose administration

Tinidazole 15 mg/kg was administered to eight Beagle dogs with gingivitis or periodontitis twice daily for 3 days. Tinidazole concentrations in blood and gingival crevicular fluid (GCF) were measured 1, 3, 6 and 9 h after the morning dose each day. The concentration of tinidazole was determined by high performance liquid chromatography (HPLC). The mean concentration of tinidazole in GCF for each dog ranged from 6.05 to 9.32 micrograms/mL at different time points after the first dose, and on the first day the highest concentration was observed 6 h after the drug administration. Tinidazole concentrations were 34 +/- 4%-72 +/- 9% (mean +/- SEM) of simultaneous plasma concentration. At steady-state, on the third treatment day, the mean tinidazole concentrations in GCF ranged from 6.68 to 13.1 micrograms/mL, i.e. 44 +/- 6%-75 +/- 25% of the corresponding concentrations in plasma. Tinidazole concentration in GCF exceeded the MIC values for putative path-ogenic periodontal bacteria and it is concluded that, when indicated, tinidazole could be used for chemotherapy of periodontitis in dogs.