title: In situ-gelling gellan formulations as vehicles for oral drug delivery.
abstract: Gels formed in situ following oral administration of 1% (w/v) aqueous solutions of gellan to rats and rabbits were evaluated as sustained-release vehicles. The formulation contained calcium ions in complexed form, the release of which in the acidic environment of the stomach caused gelation of the gellan gum. The in vitro release of theophylline from the rigid gellan gels followed root-time kinetics over a period of 6 h. Plasma levels of theophylline after oral administration of gellan solutions and a commercial oral sustained-release liquid dosage form containing an identical drug concentration were compared in both rats and rabbits. Bioavailability of theophylline from gellan gels formed by in situ gelation in the animal stomach was increased by four-fivefold in rats and threefold in rabbits compared with that from the commercial oral formulation. There was no significant difference in the mean residence times of theophylline when administered by these two vehicles.
authors.affiliation: Faculty of Pharmaceutical Sciences, Health Science University of Hokkaido, Ishikari-Tohbetsu, Hokkaido 061-0293, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Miyazaki
authors.forename: H
authors.initials: H
authors.lastname: Aoyama
authors.forename: N
authors.initials: N
authors.lastname: Kawasaki
authors.forename: W
authors.initials: W
authors.lastname: Kubo
authors.forename: D
authors.initials: D
authors.lastname: Attwood
mesh_terms: D000284:Administration, Oral; D000758:Anesthesia; D000818:Animals; D001682:Biological Availability; D003692:Delayed-Action Preparations / Q000493:pharmacokinetics*; D016503:Drug Delivery Systems; D005215:Fasting; D005753:Gastric Mucosa / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D014677:Pharmaceutical Vehicles / Q000737:chemistry*; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D013045:Species Specificity; D013806:Theophylline / Q000097:blood*; D013997:Time Factors; D014665:Vasodilator Agents / Q000097:blood
chemical_list: D003692:Delayed-Action Preparations; D014677:Pharmaceutical Vehicles; D011135:Polysaccharides, Bacterial; D014665:Vasodilator Agents; C048288:gellan gum; D013806:Theophylline