Pharmacokinetics characterization and toxicology of PNIPAAm-PEO nanoparticles loaded norvancomycin in rabbit eyes / 中华实验眼科杂志

ABSTRACT

Background The penetration of bacterial agents into the vitreous cavity is difficult because of the existence of blood-retina barrier.So conventional drug therapy is not enough effective on endophthalmitis.Drug delivery systems can decrease drug dose and reduce the drug toxicity.To construct nano controlled-release system of anti-bacterial agents is very important for the treatment of intraocular infectious diseases.Objective This study was to investigate the toxicology and intraocular pharmacoklnetics of intravitreal PNIPAAm-PEO loaded norvancomycin nanoparticles (NV-PNIPAAm-PEO) in normal rabbit eyes.Methods NV-PNIPAAm-PEO was constructed with the drug-loading rate about 22％,and then the drug gelatin solution (20 g/L) was prepared using normal saline solution.Forty-one New Zealand albino rabbits were randomized divided into experimental group and control group.20 g/L drug gelatin solution 0.1 ml was monocularly injected into the vitreous cavity in the experimental group,and the equal volume of sterilized normal saline solution was used in the control group.In 1 day,2,3,7,14,21 and 28 days after injection,ocular anterior and posterior segments were examined by slit lamp microscope and Bsonography,and electroretinogram (ERG) was recorded and the histopathological examination was performed to evaluate the biotoxicity of the drug.Norvancomycin contents in the cornea homogenate,aqueous humor,vitreous,retinochoroid homogenate were detected by high performance liquid chromatography (HPLC) system.Results The anterior and posterior segments were normal by the slit lamp microscope and B-sonography 1-28 days after injection of NV-PNIPAAm-PEO.In 7,14,21 and 28 days after injection,there were no statistically significant difference in the a-wave latency and amplitude of max-ERG between the two groups,as well as the b-wave amplitude(P＞0.05).The histopathological examination showed that the retinal structure was normal in both groups.HPLC assay showed that the norvancomycin level was gradually declined in different eye tissues from 1 day through 28 days after injection.Norvancomycin was undetectable in the cornea during the observing duration.The maximal norvancomycin content in the blood plasma was (0.34 ± 0.11) mg/L in the second day,and norvancomycin content ranged (0.08 ± 0.04)-(2.16±0.07) mg/L in the aqueous humor,(0.11 ±0.22)-(2.54 ±0.38) μg/g in the chorioretina,respectively.The drug concentration was (5.65 ± 1.14)-(406.69 ± 21.05) mg/L in the vitreous,which was higher than the minimal inhibitory concentration (MIC) to the most gram-positive bacteria.Conclusions The intravitreal injection of 22％ NV-PNIPAAm-PEO maintains the therapeutic drug concentration till 21 days in vitreous without the toxic effect on eye tissues,suggesting a great treating potential for intraocular infecting diseases.