PERIODONTAL TISSUE DISPOSITION OF AZITHROMYCIN

THE TISSUE PENETRATION OF AZITHROMYCIN, the prototype of a new class o f macrolide antibiotics named azalides, was studied in patients underg oing surgery for third-molar removal. Drug concentrations in plasma, s aliva, and periodontal tissues were evaluated in 28 patients treated w ith azithromycin 500 mg/day per os for 3 consecutive days. Samples of blood, saliva, gingiva, and alveolar bone were collected during oral s urgery, 12 hours, and 2.5, 4.5, and 6.5 days after the last dosing, an d the azithromycin concentration was measured microbiologically by usi ng Micrococcus luteus NCTC 8440 as the reference organism. The highest concentrations of azithromycin were observed 12 hours after the last dose in plasma, saliva, gingiva, and bone (0.33 +/- 0.04 mg/l, 2.14 +/ - 0.30 mg/l, 6.47 +/- 0.57 mg/kg, and 1.86 +/- 0.15 mg/kg, respectivel y) and then declined gradually. However, consistent levels of the drug in saliva and periodontal tissues could be detected up to 6.5 days, i ndicating that azithromycin was retained in target tissues and fluids for a long time after the end of treatment. Among the samples examined , the highest concentration of azithromycin was found in the gingiva a t each time studied. Moreover, the ratios of salivary or periodontal t issue levels versus plasma concentrations remained nearly unmodified f rom 12, hours up to 6.5 days. Overall, these results indicate a favora ble disposition of azithromycin into saliva and periodontal tissues an d suggest that this macrolide antibiotic represents a valuable option in the pharmacologic treatment of odontogenic infections.