INTRODUCTION: PHARMACOKINETICS: Elevated concentration of tetracycline in gingival fluid with respect to blood levels was an unexpected phenomenon. Patients given 250 mg every 6 hours had average crevicular fluid concentrations between 4 to 8 g/ml and blood concentrations between 2 to 2.5 g/ml after 48 hours. The levels in crevicular fluid and blood of volunteers who received 250 mg every 12 hours were 2 to 4 g/ml and 0.3 to 1.4 g/ml respectively after 48 hours. The concentration of doxycycline in gingival fluid after administration of 200 mg/1st day and then 100 mg/day achieved average level of 6 g/ml. Minocycline, a semisynthetic derivate of tetracycline, has shown to yield gingival fluid levels 5 times as high as serum levels after administration of 100 mg every 12 hours. MECHANISMS OF ACTION:
Tetracycline and its derivates demonstrate high in vitro activity against most periodontal bacteria, including Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Eikenella corrodens, Wolinella recta and Fusobacterium nucleatum. The study of in vitro susceptibility of these 6 bacterial strains showed that, in regard to blood level, minimal inhibitory concentration is higher and it is the concentration of the drug that can be expected in gingival fluid following oral administration of 100 mg per day ( doxycycline) (Table 1). The anti-inflammatory effect of tetracyclines was demonstrated histologically not only by reducing the size of the infiltrated connective tissue, but qualitative changes were also observed. Golub and associates have presented evidence that tetracyclines inhibit collagenase activity in gingival fluid and in tissue cultures. Therapeutic concentrations of tetracycline inhibit chemotaxis, phagocytosis and random migration of neutrophils in vitro. ADVERSE EFFECTS: INTERACTIONS: INDICATIONS: RESULTS OF CLINICAL STUDY: ORAL APPLICATION: In spite of great number of published investigations this paper presents only the results of placebo-controlled, double-blind studies. There is evidence that therapy in localized juvenile periodontitis should eliminate Actinobacillus actinomycetemcomitans, since 95% of patients harbored this bacteria. (ABSTRACT TRUNCATED)
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