title: Precorneal clearance of mucoadhesive microspheres from the rabbit eye.
abstract: The ocular disposition of hydrated 111In-labelled microspheres was investigated in the rabbit by gamma scintigraphy. Microspheres of cross-linked poly(acrylic acid) (Carbopol 907) were prepared by a w/o emulsification process. An in-vitro mucoadhesion test of prehydrated microspheres showed that greater adhesion was achieved to a mucus gel at pH 5.0 compared with pH 7.4. Clearance was a biphasic process with a rapid initial phase preceding a slower basal phase. When hydrated in pH 5.0 phosphate buffered saline, clearance during the basal phase was slowed compared with a pH 7.4 buffered preparation. Both prehydrated preparations were retained on the preocular area during the basal phase for longer periods than non-hydrated microspheres. The retention on the ocular surface of approximately 25% of the instilled dose would suggest this technology will have application for controlled ophthalmic drug delivery.
authors.affiliation: Welsh School of Pharmacy, UWC, Cardiff, UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Durrani
authors.forename: S J
authors.initials: SJ
authors.lastname: Farr
authors.forename: I W
authors.initials: IW
authors.lastname: Kellaway
mesh_terms: D000180:Acrylic Resins; D000268:Adhesiveness; D000818:Animals; D003315:Cornea / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004655:Emulsions; D005123:Eye / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007205:Indium Radioisotopes / Q000493:pharmacokinetics*; D008863:Microspheres; D011145:Polyvinyls / Q000737:chemistry* / Q000378:metabolism; D011817:Rabbits
chemical_list: D000180:Acrylic Resins; D003432:Cross-Linking Reagents; D004655:Emulsions; D007205:Indium Radioisotopes; D011145:Polyvinyls; C006912:carboxypolymethylene