Vitreous and aqueous penetration of orally and topically administered moxifloxacin.

AIM

It was the aim of this study to compare the pharmacokinetics of moxifloxacin (MFLX) hydrochloride in rabbits after topical and oral administration.

METHODS

Three 50-μl applications of MFLX (0.5%) topical ophthalmic solution were instilled into the cul-de-sac of New Zealand white rabbits at 15-min intervals. Aqueous and vitreous samples were collected and analyzed 30-240 min after the final instillation. Assays were performed using high-performance liquid chromatography. MFLX (16 mg/kg of body weight) was administered orally. Drug concentrations in aqueous, vitreous and serum samples, collected at 30-360 min after administration, were determined using high-performance liquid chromatography.

RESULTS

After topical administration, the maximum concentrations of MFLX in the aqueous and vitreous samples were 10.2 ± 1.6 μg/ml (30 min; n = 6) and 0.10 ± 0.03 μg/ml (30 min; n = 6), respectively. After oral administration, the maximum concentrations in the aqueous, vitreous and serum samples were 0.9 ± 0.3 μg/ml (120 min; n = 6), 0.7 ± 0.2 μg/ml (240 min; n = 6) and 1.6 ± 0.9 μg/ml (120 min; n = 6), respectively. The percentages of serum MFLX concentration in the aqueous and vitreous samples after oral administration were 55.2 and 41.7%, respectively.

CONCLUSIONS

The aqueous concentration of MFLX was about 10-fold higher after topical than after oral administration. However, intravitreal MFLX concentrations after oral administration were about 7-fold higher than those after topical administration. The MFLX concentrations in the aqueous humor following oral administration exceeded the minimum inhibitory concentration for 90% of the bacteria involved in ocular infection.