Penetration of doxycycline in respiratory mucosa

In order to study the penetration of doxycycline (Idocyklin) in respiratory mucosa 100 mg tablets were given in standard dosage to 58 patients with longstanding secretory otitis media, the "secretion-in-cavity" model, and to 37 patients with nasal polyposis, the tissue model. Myringotomy with aspiration of the middle ear secretion or polypectomy was performed at different intervals during the course of medication. Blood samples were drawn simultaneously. The concentration in secretion, tissue and serum was assessed by means of a microbiological agar well method. The mean concentration of doxycycline in respiratory mucosa and secretion was found to exceed the MICs of the common respiratory pathogens as soon as 3 hours after the first dose, and remained on a therapeutical level until 24 hours after the last dose. The results are in full agreement with those obtained from penetration studies in other parts of the respiratory tract, thereby lending support to the validity of the models used.