title: Xyloglucan as a novel vehicle for timolol: pharmacokinetics and pressure lowering activity in rabbits.
abstract: This study was aimed at verifying the performances of a mucoadhesive polysaccharide from tamarind seed (xyloglucan or TSP, tamarind seed polysaccharide) as an adjuvant for ophthalmic vehicles containing timolol. Three formulations (one experimental vehicle based on TSP and two reference commercial eye drops) containing 5 mg/ml timolol base equivalents were administered to the eyes of pigmented rabbits. Drug concentrations in tear fluid, cornea, iris-ciliary body, aqueous humor and plasma were determined, as well as intraocular pressure. The polymer under investigation, in spite of a comparatively low viscosity, produced high timolol concentrations in the ocular tissues and a low systemic absorption. The performances of the TSP vehicle were comparable to those of a reference "in situ" gelling formulation (Timoptic XE). The results point to TSP as a potentially useful adjuvant for ophthalmic delivery systems.
authors.affiliation: Department of Bioorganic Chemistry and Biopharmaceutics, University of Pisa, Italy. burgal@farm.unipi.it
authors.forename: S
authors.initials: S
authors.lastname: Burgalassi
authors.forename: P
authors.initials: P
authors.lastname: Chetoni
authors.forename: L
authors.initials: L
authors.lastname: Panichi
authors.forename: E
authors.initials: E
authors.lastname: Boldrini
authors.forename: M F
authors.initials: MF
authors.lastname: Saettone
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000493:pharmacokinetics* / Q000494:pharmacology; D000818:Animals; D000869:Anterior Eye Segment / Q000378:metabolism*; D001082:Aqueous Humor / Q000378:metabolism; D019540:Area Under Curve; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D002924:Ciliary Body / Q000378:metabolism; D003315:Cornea / Q000378:metabolism; D016503:Drug Delivery Systems; D005260:Female; D005936:Glucans; D007429:Intraocular Pressure / Q000187:drug effects*; D007498:Iris / Q000378:metabolism; D008297:Male; D014677:Pharmaceutical Vehicles / Q000493:pharmacokinetics / Q000494:pharmacology; D011134:Polysaccharides / Q000493:pharmacokinetics* / Q000494:pharmacology; D011817:Rabbits; D013666:Tears / Q000378:metabolism; D013999:Timolol / Q000493:pharmacokinetics* / Q000494:pharmacology; D014018:Tissue Distribution; D014990:Xylans
chemical_list: D000319:Adrenergic beta-Antagonists; D005936:Glucans; D014677:Pharmaceutical Vehicles; D011134:Polysaccharides; D014990:Xylans; C029353:xyloglucan; D013999:Timolol