title: Mucoadhesive ophthalmic vehicles: evaluation of polymeric low-viscosity formulations.
abstract: A series of polyanionic natural or semi-synthetic polymers (polygalacturonic acid, hyaluronic acid, carboxymethylamylose, carboxymethylchitin, chondroitin sulfate, heparan sulfate and mesoglycan) were evaluated as potential mucoadhesive carriers for ophthalmic drugs. Solutions containing cyclopentolate (CY) or pilocarpine (PI) as salts (or polyanionic complexes) with the acidic polymers, all showing a low viscosity, were tested for miotic (resp. mydriatic) activity in albino rabbits. In the case of some polymeric complexes, small but significant increases of the areas under the activity vs. time curves (AUC) over reference cyclopentolate hydrochloride (CYHC1) or pilocarpine nitrate (PINO3) vehicles, and significant AUC decreases after removal of precorneal mucin by treatment with N-acetylcysteine were observed. A correlation was found between these data, considered indicative of the occurrence of a mucoadhesive interaction "in vivo", and "in vitro" viscometric data expressing the polymers-mucin force of interaction. The advantages and limitations of the mucoadhesive non-viscous approach in the formulation of ophthalmic vehicles are presented and discussed.
authors.affiliation: Laboratory of Pharmaceutical Technology/Biopharmaceutics, University of Pisa, Italy.
authors.forename: M F
authors.initials: MF
authors.lastname: Saettone
authors.forename: D
authors.initials: D
authors.lastname: Monti
authors.forename: M T
authors.initials: MT
authors.lastname: Torracca
authors.forename: P
authors.initials: P
authors.lastname: Chetoni
mesh_terms: D000268:Adhesiveness; D000818:Animals; D003315:Cornea / Q000378:metabolism*; D003519:Cyclopentolate / Q000493:pharmacokinetics*; D004337:Drug Carriers; D016503:Drug Delivery Systems / Q000379:methods; D005069:Evaluation Studies as Topic; D008297:Male; D009077:Mucins / Q000378:metabolism*; D009883:Ophthalmic Solutions; D014677:Pharmaceutical Vehicles / Q000378:metabolism; D010862:Pilocarpine / Q000493:pharmacokinetics*; D011108:Polymers / Q000378:metabolism; D011817:Rabbits; D011897:Random Allocation; D012212:Rheology; D014783:Viscosity
chemical_list: D004337:Drug Carriers; D009077:Mucins; D009883:Ophthalmic Solutions; D014677:Pharmaceutical Vehicles; D011108:Polymers; D010862:Pilocarpine; D003519:Cyclopentolate