Abstract
Abstract: :
Purpose: The intravitreal injection is regarded as one of the most effective mode of treatment for bacterial endophthalmitis. We(Nippon Ganka Gakkai Zasshi, 1996) and Gurler et al(Current Eye Research, 2002) reported that an intravitreal injection of 500 µg of levofloxacin(LVFX ) caused no retinal toxicity in the rabbit. To examine the efficacy of an intravitreal injection of LVFX, we studied the pharmacokinetics after an intravitreal injection of LVFX. Methods: Thirty albino rabbits and 30 pigmented rabbits were used. A dose of 500µg of 14C–LVFX were intravitreally injected into the right eye. The rabbits were sacrificed 6hr (n=5), 12hr (n=5), 24hr (n=5), 48hr (n=5), 72hr (n=5) and 1week (n=5) after the injection. The eye was immediately enucleated, the optic nerve and blood were obtained. The cornea, the conjunctiva, the sclera, the iris–ciliary body, the aqueous humor, the lens, the vitreous body, the neural retina and the choroid–RPE were obtained from each eye. The concentrations of LVFX were determined from the radioactivity in each sample measured by a liquid scintillation counter. Results: The intravitreal concentration of LVFX was similar in both albino and pigmented rabbits. The intravitreal concentration of LVFX remained above the MIC90 of LVFX for major pathogens of endophthalmitis for at least 24hr. The LVFX concentration in the melanin–containing tissues such as the iris–ciliary body and the choroid–RPE was significantly higher in pigmented rabbits than in albino rabbits at each measuring point. The LVFX concentration in the choroid–RPE 1week after the injection was not detectable in albino rabbits, and 13.87µg/g in pigmented rabbits. Conclusions: The intravitreal injection of LVFX may be clinically useful for the treatment of endophthalmitis. Because of its delayed clearance in melanin–containing ocular tissues, repeated injections of high dose of LVFX may not be recommended for colored patients.
Keywords: endophthalmitis • drug toxicity/drug effects • vitreous