title: Undefined role of mucus as a barrier in ocular drug delivery.
abstract: Mucus layer covers the ocular surface, and soluble mucins are also present in the tear fluid. After topical ocular drug administration, the drugs and formulations may interact with mucus layer that may act as a barrier in ocular drug delivery. In this mini-review, we illustrate the mucin composition of the ocular surface and discuss the influence of mucus layer on ocular drug absorption. Based on the current knowledge the role of mucus barrier in drug delivery is still undefined. Furthermore, interactions with mucus may prolong the retention of drug formulations on the ocular surface. Mucus may decrease or increase ocular bioavailability depending on the magnitude of its role as barrier or retention site, respectively. Mechanistic studies are needed to clarify the role of mucin in ocular drug delivery.
authors.affiliation: School of Pharmacy, University of Eastern Finland, Kuopio, Finland.
authors.forename: Marika
authors.initials: M
authors.lastname: Ruponen
authors.affiliation: School of Pharmacy, University of Eastern Finland, Kuopio, Finland; Centre for Drug Research, Division of Pharmaceutical Biosciences, University of Helsinki, Helsinki, Finland. Electronic address: arto.urtti@uef.fi.
authors.forename: Arto
authors.initials: A
authors.lastname: Urtti
mesh_terms: D065567:Absorption, Physiological; D060433:Administration, Ophthalmic; D000818:Animals; D018916:Blood-Aqueous Barrier / Q000737:chemistry / Q000378:metabolism*; D001813:Blood-Retinal Barrier / Q000737:chemistry / Q000378:metabolism; D003228:Conjunctiva / Q000737:chemistry / Q000378:metabolism; D003315:Cornea / Q000737:chemistry / Q000378:metabolism; D004337:Drug Carriers / Q000008:administration & dosage / Q000493:pharmacokinetics; D005123:Eye / Q000737:chemistry / Q000378:metabolism*; D019276:Glycocalyx / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007765:Lacrimal Apparatus / Q000737:chemistry / Q000378:metabolism; D009077:Mucins / Q000737:chemistry / Q000378:metabolism; D009092:Mucous Membrane / Q000737:chemistry / Q000378:metabolism*; D009093:Mucus / Q000737:chemistry / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry; D010539:Permeability; D010599:Pharmacokinetics; D014018:Tissue Distribution
chemical_list: D004337:Drug Carriers; D009077:Mucins
keywords: Conjunctival permeation; Corneal permeation; Mucin; Mucoadhesion; Mucus; Nanoparticle; Ocular drug delivery