Pharmacokinetics of cefaclor in chronic middle ear effusions.

Fifty children aged 1 to 13 years with chronic or recurrent otitis media with effusion received a single dose of cefaclor (15 mg/kg body weight) by the oral route 30 minutes to seven hours before the removal of middle ear effusion and insertion of tympanostomy tubes. Serum and middle ear aspirate concentrations of the antibiotic were determined employing a microbiological assay technique by a disk diffusion method. Middle ear specimens were also cultured for aerobic bacteria. The mean peak serum concentration level (8.49 +/- 7.89 micrograms/ml) was observed after 30 minutes, whereas the middle ear peak level (0.47 +/- 0.78 micrograms/ml) occurred after one hour. Of the 87 middle ear specimens, 37 had cefaclor concentrations which were detectable within the resolution of the bioassay method (greater than 0.16 micrograms/ml). There was no correlation between the type of middle ear effusion (mucoid or serous) and the concentration of cefaclor in the middle ear. Only 18% of the middle ear cultures were positive for aerobic bacteria; Hemophilus influenzae was the most common organism.