Use of quinolones for treatment of ear and eye infections.

Malignant otitis externa is a severe, necrotizing infection of the external auditory canal which is sometimes fatal. The traditional antimicrobial treatment has usually been the combination of an antipseudomonal beta-lactam and an aminoglycoside, given intravenously for 4 to 8 weeks. Over 100 patients have been treated with a fluoroquinolone alone, most commonly ciprofloxacin given by mouth in a dosage of 750 mg b.i.d. for 6 to 12 weeks. About 90% of patients have been cured. Treatment with a quinolone has the advantage over older treatments that it can be given orally and has a low rate of side-effects. The ocular penetration of the fluoroquinolones has been studied in patients with unifected eyes. After the administration of a single dose of ciprofloxacin, pefloxacin, ofloxacin or norfloxacin, penetration into the aqueous humor, expressed as the ratio of the peak concentration in the aqueous humor to that in the serum, is about 20%. The penetration of ciprofloxacin into the vitreous humor, based primarily on the data from one report, is about 20%. The concentrations are likely to be higher after repeated doses or in the inflamed eye. Whether the concentrations achieved will be adequate for therapeutic or prophylactic purposes has not been determined.