Azidocillin and ampicillin concentrations in middle ear effusion.

The penetration of azidocillin and ampicillin into the middle ear effusion after oral administration was studied and compared with blood levels of the drugs. In acute otitis media one hour after a single oral dose of azidocillin (15 mg/kg) 1.56 +/- 0.44 microgram/ml of the drug was found in the effusion fluid; after 2 hours the fluid contained 3.21 +/- 0.87 microgram/ml and after 12 hours,0.84 +/- 0.13 microgram/ml. The concentrations of ampicillin were 1.15 +/- 0.23 microgram/ml after one hour, 2.17 +/- 0.46 microgram/ml after 2 hours and 1.09 +/- 0.22 microgram/ml after 8 hours following a single oral dose of 10 mg/kg. Both drugs stay longer in the middle ear secretion than in the blood. This persistence supports the administration of azidocillin twice daily in acute otitis media. In contrast, the penetration of the drugs into the middle ear effusion fluid was poor in secretory otitis media, where the levels of the drugs were significantly lower.