Metronidazole concentrations in plasma, saliva and periodontal pockets in patients with periodontitis.

OBJECTIVES: Metronidazole is widely used antibacterial compound in the treatment of some types of periodontal disease. Pharmacokinetics of metronidazole in plasma has been well-described but few data exist about penetration of the drug to the gingival crevice fluid. The aim of the present study was to compare the concentrations of metronidazole in plasma, saliva and gingival crevice fluid in patients with periodontitis after multiple administration. MATERIALS AND METHODS: Eleven patients with severe generalised adult periodontitis participated in the study. Metronidazole, 500 mg, was administered orally two or three times per day for at least 2 days before sample collection. Samples were collected 2 h after last dose. Metronidazole concentrations in all fluids were measured with high-performance liquid chromatography. RESULTS: Mean drug concentrations in plasma, saliva and crevice fluid were 14.33, 15.15 and 12.86 microg/ml, respectively. Difference between plasma and crevice fluid or between plasma and saliva did not reach statistical significance. CONCLUSION: Present study revealed that metronidazole penetrates well into gingival crevice fluid and saliva. Metronidazole concentrations in crevice fluid are about equal to the protein unbound drug concentrations in plasma. Therefore, general pharmacokinetic data of metronidazole can be also applied in the treatment of periodontal disease and in the design of respective treatment regimens.