Abstract
Purpose: :
Although topical drug delivery is a convenient route of administration to treat various eye diseases, it has serious limitations due to rapid clearance of the formulation from the surface of the eye. In this study, we engineered microparticles for both sustained drug delivery and prolonged residence time on the extraocular surface.
Methods: :
Microparticles were fabricated by emulsification using poly(lactic-co-glycolic acid) (PLG) and poly(ethylene glycol) (PEG) as the core material and mucoadhesion promoter, respectively. Mucoadhesiveness of the microparticles was tested in vitro using a hydrophilic membrane (cellulose nitrate) pre-soaked with an aqueous mucin solution. The number of remaining particles on a membrane was measured after washing with a continuous flow of Hank’s solution. Retention of PLG/PEG microparticles on the surface of the eye was also examined in vivo. The rabbit was anesthetized to control blinking and obtain still images of the microparticles remaining on the eye.
Results: :
Microparticles were fabricated out of only PLG and out of a blend of PLG and PEG to compare the effect of PEG on microparticle adhesion to the mucous surface of the eye. The size of the microparticles was also controlled to be less than 10 µm to minimize eye irritation and for eventual clearance through the lacrimal canals. In vitro mucoadhesion tests showed that PLG/PEG microparticles adhered to the mucin-soaked membrane to a 48% greater extent than PLG microparticles after washing with a continuous flow of Hank’s solution (Student’s t-test, p < 0.05). We also assessed the retention of PLG/PEG particles on the rabbit eye in vivo. Immediately after administration, some of the microparticles were observed on the cornea and near the limbus. After 5 min, most microparticles were removed from the cornea and collected at the inferior and superior fornix under the lower and upper eyelids, respectively, and in the lacrimal caruncle. At 30 min after administration, the remaining microparticles were still present in the lower fornix.
Keywords: cornea: surface mucins • cornea: tears/tear film/dry eye • eyelid