title: Microemulsions as topical delivery vehicles: ocular administration of timolol.
abstract: The topical administration of timolol as an ion-pair with octanoate was achieved by use of an oil-in-water microemulsion containing lecithin as a surfactant. The microemulsion, a solution of the ion-pair and a solution of timolol alone were instilled in the conjunctival sac of rabbits. A rapid method for the separation and determination of timolol in aqueous humour by HPTLC was used. The bioavailability of timolol from the microemulsion and the ion-pair solution was higher than that obtained from timolol alone. The areas under the curve for timolol in aqueous humour after administration of the microemulsion and the ion-pair solution were 3.5 and 4.2 times higher, respectively, than that observed after the administration of timolol alone.
authors.affiliation: Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Turin, Italy.
authors.forename: M R
authors.initials: MR
authors.lastname: Gasco
authors.forename: M
authors.initials: M
authors.lastname: Gallarate
authors.forename: M
authors.initials: M
authors.lastname: Trotta
authors.forename: L
authors.initials: L
authors.lastname: Bauchiero
authors.forename: E
authors.initials: E
authors.lastname: Gremmo
authors.forename: O
authors.initials: O
authors.lastname: Chiappero
mesh_terms: D000042:Absorption; D000287:Administration, Topical; D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D002855:Chromatography, Thin Layer; D003315:Cornea / Q000378:metabolism*; D004355:Drug Stability; D004655:Emulsions; D014677:Pharmaceutical Vehicles; D011817:Rabbits; D013050:Spectrometry, Fluorescence; D013999:Timolol / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000633:toxicity
chemical_list: D004655:Emulsions; D014677:Pharmaceutical Vehicles; D013999:Timolol