Roxithromycin penetration into gingiva and alveolar bone of odontoiatric patients

The concentrations of the new macrolide antibiotic roxithromycin in plasma, saliva, gingiva, and alveolar bone were studied in 24 odontoiatric patients treated with a first dose of 300 mg p.o. followed by three maintenance doses of 150 mg p.o., 12-hourly. Samples of blood, saliva, gingiva, and bone were collected at various time points up to 24 h after the last dosing, and the roxithromycin concentration was measured microbiologically, using Bacillus subtilis ATCC 6633 as the reference organism. Pharmacokinetic analysis was performed according to a two-compartment open model with first-order absorption. The plasma, gingiva, and alveolar bone peak concentrations were 6.12 ± 1.94 mg/l, 6.55 ± 2.54 mg/kg, and 5.09 ± 1.60 mg/kg, respectively. Low levels of roxithromycin were detected in saliva (0.67 ± 0.12 mg/l at the 3rd h). The values of the area under the concentration-time curve for plasma, gingiva, and bone were 59.47 mg/l · h, 51.88 mg/kg · h and 46.80 mg/kg · h, respectively; the half-life values were 7.52 h for plasma and 6.36 and 5.20 h for gingiva and bone, respectively. These results indicate that roxithromycin reaches high levels in periodontal tissues.