Comparison of concentrations of amoxicillin and ampicillin in serum and middle ear fluid of children with chronic otitis media.

Twenty-eight children aged five to nine years with chronic serous otitis media received a single dose of either ampicillin or amoxicillin by the oral route 1-2 hr before the removal of middle ear fluid by ventilation tubes inserted through the tympanic membrane. At the time middle ear fluid was obtained, a sample of blood was drawn from the patient, and levels of antibiotic in both specimens were microbiologically assayed by a disk diffusion method. Levels of amoxicillin (mean+/-standard error [SE], 1.48+/-1.6 microng/ml) in middle ear fluid were consistently and significantly higher (P less than 0.05) than levels of ampicillin (mean+/-SE, 6.2+/-5.0 microng/ml).