title: In-situ ocular absorption of ophthalmic beta-blockers through ocular membranes in albino rabbits.
abstract: Ocular membranes have been characterized by in-situ absorption of the ophthalmic beta-blockers carteolol (hydrophilic) and timolol and befunolol (lipophilic) using a cylindrical cell. After introduction of drug solution into the cell on the cornea, sclera (bulbar conjunctival and scleral layer) or palpebral conjunctiva, the disappearance of the drug from the cell was determined as in-situ absorption. The ophthalmic drugs disappeared from the conjunctival and scleral membranes although disappearance from the cornea was hardly observed. The conjunctival membrane showed the highest permeability. Lipophilic drugs were more permeable than hydrophilic. In-situ apparent permeability coefficients of the ophthalmic drugs through the conjunctiva and sclera correlated with the lipophilicity of drugs. A high drug concentration in the aqueous humor was observed after corneal application. There is a relationship between concentration in the aqueous humor was observed after corneal application. There is a relationship between concentrations of drugs in the aqueous humor and previously reported in-vitro apparent permeability coefficients of the drugs in the cornea. This in-situ method using a cylindrical cell is a useful method of investigating the ocular absorption of ophthalmic drugs.
authors.affiliation: Department of Hospital Pharmacy, Nagasaki University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sasaki
authors.forename: M
authors.initials: M
authors.lastname: Ichikawa
authors.forename: S
authors.initials: S
authors.lastname: Kawakami
authors.forename: K
authors.initials: K
authors.lastname: Yamamura
authors.forename: T
authors.initials: T
authors.lastname: Mukai
authors.forename: K
authors.initials: K
authors.lastname: Nishida
authors.forename: J
authors.initials: J
authors.lastname: Nakamura
mesh_terms: D000042:Absorption; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000818:Animals; D002354:Carteolol / Q000493:pharmacokinetics; D003228:Conjunctiva / Q000378:metabolism; D003315:Cornea / Q000378:metabolism; D005123:Eye / Q000378:metabolism*; D008297:Male; D011412:Propanolamines / Q000493:pharmacokinetics; D011817:Rabbits; D012590:Sclera / Q000378:metabolism; D013999:Timolol / Q000493:pharmacokinetics
chemical_list: D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; C006034:befunolol; D013999:Timolol; D002354:Carteolol