title: Hydrogels formed by cross-linked polyvinylalcohol as colon-specific drug delivery systems.
abstract: Polyvinivlalcohol (PVA, of different molecular weights was cross-linked with succinyl, adipoyl, or sebacoyl chloride to obtain hydrogel-forming polymers and to determine their suitability as colon-specific drug delivery systems. Diclofenac sodium, propranolol hydrochloride, and vitamin B6 hydrochloride were used as hydrophilic model drugs with colon-specific release that should yield high concentrations in the large intestine, minimizing release in the upper part of the gastrointestinal tract. Spray -dried mixtures of the drugs and the polymer (at a 1:2 w/w ratio) were prepared, and the release of the drugs from the mixtures was evaluated in vitro at pH 2.0, 5.5, and 7.4. The results indicated the ability of the cross-linked polymers to slow the release of the drugs analyzed with respect to the pure drug dissolution at each pH. The lengthening of the cross-linker acyl chain was noted to decrease drug release further.
authors.affiliation: Department of Pharmaceutical Sciences, Bologna University, Italy. orienti@biocfarm.unibo.it
authors.lastname: Orienti
authors.forename: R
authors.initials: R
authors.lastname: Treré
authors.forename: V
authors.initials: V
authors.lastname: Zecchi
mesh_terms: D000465:Algorithms; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003106:Colon; D003432:Cross-Linking Reagents; D004008:Diclofenac / Q000008:administration & dosage / Q000737:chemistry; D016503:Drug Delivery Systems; D020100:Hydrogels / Q000737:chemistry*; D008970:Molecular Weight; D010316:Particle Size; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D011433:Propranolol / Q000008:administration & dosage / Q000737:chemistry; D012996:Solutions; D025101:Vitamin B 6 / Q000008:administration & dosage / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D020100:Hydrogels; D012996:Solutions; D004008:Diclofenac; D025101:Vitamin B 6; D011142:Polyvinyl Alcohol; D011433:Propranolol