Tissue concentrations of ofloxacin in the middle ear

Abstract

Twenty patients with chronic otitis media underwent tympanoplasty and were given an oral dose (two 200-mg tablets) of a new antibiotic, ofloxacin, three to seven hours before surgery. The study aimed to demonstrate satisfactory concentrations of ofloxacin in the middle ear as the basis for that agent's well-known clinical efficacy. The main pathogens responsible for bacterial infections in the ear, nose, and throat, especially those in the ear, are Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and alpha-streptococci. The chemotherapeutic agent used must reach adequate concentrations in the bone, mucous membrane, and serum. Mucous membrane, bone, and serum samples were obtained from the middle ear and examined for ofloxacin levels. The medication was also administered for a minimum of five days postoperatively. The average serum level of ofloxacin was 2.1 micrograms/ml, and the concentrations in both the mucous membrane and bone (2.2 micrograms/gm) were above the serum levels. The extent to which the concentrations at the possible site of infection exceeded the minimal inhibitory concentrations (MICs) for the pathogens was investigated at our clinic in 190 isolates. The study showed that, with the leading pathogens such as staphylococci, tissue concentrations were about four times higher than the MICs and that even Pseudomonas organisms were effectively inhibited. All patients had a satisfactory clinical response to therapy. The authors thus recommend a dosage of 400 mg of ofloxacin three to five hours prior to surgery for middle ear infection.