Gentamicin persistence in rat endolymph and perilymph after a two-day constant infusion.

The kinetics of gentamicin in the inner ear fluids of rats were studied up to 15 days after cessation of a 2-day constant infusion of 10 micrograms/min. In endolymph, the concentration of gentamicin persisted at about 1 microgram/ml for up to 15 days, precluding the determination of the half-life of the drug in this fluid. In perilymph, gentamicin cleared more slowly than after a shorter period of infusion. These results suggest that the tissues of the inner ear could bind the aminoglycoside and then slowly release it into the surrounding fluids.