Abstract
Purpose:
The purpose of this study was to investigate the biocompatibility of biodegradable in situ forming depots composed of a mixture of poly(lactide)-b-poly(ethylene glycol)-b-poly(lactide) (PLA-PEG-PLA) and methoxy-poly(ethylene glycol)-b-poly(lactide) (mPEG-PLA) after intravitreal administration in rabbits.
Methods:
Two different MedinGel formulations were administered as single intravitreal 5-μl injections into the right eyes (RE) of healthy rabbits, using 27G needles. As control, animals also received 5-μl saline solution intravitreal injections of the left eyes (LE). Biocompatibility was monitored by slit lamp biomicroscopy with McDonald-Shadduck scoring, fundus evaluation and intraocular pressure assessment (IOP) for two weeks and, after sacrifice of the animals at 2 weeks, by macroscopic observations and ocular histopathology.
Results:
There were no adverse effects related to body weight, body weight gain, food and water consumption. After intravitreal injection, the depots as well as the saline solutions induced a transient conjunctival chemosis and discharge for 24 hours, and conjunctival redness for 72 hours. No significant variation in IOP was observed in any of the animals during the duration of the study. Close to the injection site: retinal layers were disorganized, collagen fibers and cellular debris with macrophages were present. All these reactions were observed both in control and treated eyes. Ocular structures evaluated by histology examination disclosed no other damage after intravitreal injections of tested items. More data is also being generated on the biocompatibility of MedinGel depots after subconjunctival injection.
Conclusions:
These results indicate that MedinGel depots administered intravitrealy were well tolerated. It demonstrates that this injectable biodegradable drug delivery system is a promising vehicle for ophthalmic applications.
Keywords: 688 retina •
763 vitreous •
474 conjunctiva