Concentration of Penicillin V and Tetracycline in Maxillary Sinus Secretion after Repeated Doses

49 patients with maxillary sinus infections were given orally either penicillin V, or tetracycline, or the two drugs in combination. The antibiotic concentrations in serum and sinus secretions were determined with an agar diffusion method using paper discs as diffusion centers. In only 8 out of 28 purulent secretions was it possible to demonstrate measurable concentrations of penicillin V, i.e. ≥0.2 μg/ml. The concentration of tetracycline was never lower than 0.5 μg ml. The antibiotic concentrations in purulent secretions were significantly lower than in mucous secretions. With the dosage used, 1.6 g penicillin V and 1.0 g tetracycline per 24 hours, only a few secretions contained concentrations of penicillin V equal or above the upper limit of minimal inhibitory concentrations for bacterial sensitivity group I, i.e. 0.25 μg/ml. Nearly all secretions contained concentrations of tetracycline above this upper limit, i.e. 1.0 μg/ml.