Antibiotic iontophoresis in the treatment of burn perichondritis of the rabbit ear.

Perichondritis of the pinna is a serious late infection of burns involving the ear. The avascular nature of this injury renders systemic antibiotic therapy ineffective in delivering adequate levels of drug to the area to provide antimicrobial activity. Treatment has traditionally been surgery in some form, resulting in further disfigurement of the damaged cartilagenous framework. Iontophoresis, a method of dispersing charged particles through a relatively impermeable membrane by a light electrical field, appears to be a feasible method of antibiotic delivery. This initial pilot study investigated the development of perichondritic-like burns in ten rabbit ears, and techniques for gentamicin iontophoresis and assay in devitalized cartilage. Five rabbits, with ear burns simulating perichondritis, were treated with gentamicin iontophoresis on one ear and gentamicin-soaked gauze on the other. Resulting assays of the ear cartilages, after four treatments over a 2-day period, demonstrated a nearly twenty-fold increase in gentamicin levels in the iontophoresis-treated ears, compared to low levels in the soaked ears. Systemic absorption was negligible in all rabbits.