title: Oral sustained delivery of theophylline from thermally reversible xyloglucan gels in rabbits.
abstract: Thermally reversible gels formed in-situ following the oral administration of dilute aqueous solutions of an enzyme-degraded xyloglucan to rabbits were evaluated as sustained-release vehicles for the delivery of theophylline. In-vitro release of theophylline from gels formed by warming xyloglucan sols (0.5, 1.0 and 1.5% w/w) to 37 degrees C followed root-time kinetics over a period of 4 h. Gels formed after oral administration to rabbits of chilled 1.5% w/w aqueous solutions of xyloglucan containing dissolved drug showed sustained-release characteristics with a maximum plasma concentration at 4.5 h. The theophylline bioavailability from a 1.5% w/w xyloglucan gel was 1.7-2.5 times that of commercial oral sustained-release liquid dosage forms containing an identical theophylline concentration. It was concluded that dilute solutions of the enzyme-degraded xyloglucan had suitable rheological properties and in-situ gelling characteristics for use as sustained-release vehicles for oral drug delivery. The in-vivo release characteristics of theophylline in a rabbit model suggested the potential for the use of these vehicles in humans for the oral delivery of this drug.
authors.affiliation: Faculty of Pharmaceutical Sciences, Health Science University of Hokkaido, Ishikari-Tohbetsu, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Miyazaki
authors.forename: N
authors.initials: N
authors.lastname: Kawasaki
authors.forename: K
authors.initials: K
authors.lastname: Endo
authors.forename: D
authors.initials: D
authors.lastname: Attwood
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D001993:Bronchodilator Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics; D003692:Delayed-Action Preparations; D005782:Gels; D005936:Glucans; D007700:Kinetics; D008297:Male; D011134:Polysaccharides / Q000737:chemistry*; D011817:Rabbits; D013696:Temperature; D013806:Theophylline / Q000008:administration & dosage* / Q000493:pharmacokinetics; D014990:Xylans
chemical_list: D001993:Bronchodilator Agents; D003692:Delayed-Action Preparations; D005782:Gels; D005936:Glucans; D011134:Polysaccharides; D014990:Xylans; C029353:xyloglucan; D013806:Theophylline