title: pH-independent sustained release matrix tablet containing doxazosin mesylate: effect of citric acid.
abstract: The aim of this study was to develop a pH-independent sustained release matrix tablets of doxazosin mesylate. The matrix tablets were prepared by direct compression technique using polyethylene oxide, sodium alginate and citric acid as a pH modifier. Formulations were evaluated for an in vitro drug release study, erosion study, and the microenvironmental pH was studied using the pH indicator methyl red. For formulations without citric acid, the extent and rate of drug release in simulated gastric fluid were much higher than those in simulated intestinal fluid. By adding the citric acid, the drug release rate in simulated intestinal fluid was increased, and microenvironmental pH values within the tablets were maintained at low pH during drug release. Furthermore, drug release from the matrix tablet containing 20% w/w citric acid was comparable to that from a commercial product, Cardura® XL, and a pH-independent release could be achieved. Therefore, the incorporation of citric acid as a pH modifier to Polyethylene oxide-sodium alginate matrix tablets effectively produced pH-independent doxazosin mesylate release profiles.
authors.affiliation: Center for Nanotechnology-based New Drug Dosage Form, College of Pharmacy, Chungnam National University, Daejeon 305-764, Korea.
authors.forename: Kwang-Ho
authors.initials: KH
authors.lastname: Cha
authors.forename: Thanh-Huyen
authors.initials: TH
authors.lastname: Tran
authors.forename: Min-Soo
authors.initials: MS
authors.lastname: Kim
authors.forename: Jeong-Soo
authors.initials: JS
authors.lastname: Kim
authors.forename: Hee Jun
authors.initials: HJ
authors.lastname: Park
authors.forename: Junsung
authors.initials: J
authors.lastname: Park
authors.forename: Wonkyung
authors.initials: W
authors.lastname: Cho
authors.forename: Sung-Joo
authors.initials: SJ
authors.lastname: Hwang
mesh_terms: D058668:Adrenergic alpha-1 Receptor Antagonists / Q000008:administration & dosage* / Q000737:chemistry*; D000464:Alginates / Q000737:chemistry; D019343:Citric Acid / Q000737:chemistry*; D003692:Delayed-Action Preparations; D017292:Doxazosin / Q000008:administration & dosage* / Q000737:chemistry*; D004339:Drug Compounding; D016503:Drug Delivery Systems; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D011092:Polyethylene Glycols / Q000737:chemistry; D012995:Solubility; D013607:Tablets
chemical_list: D058668:Adrenergic alpha-1 Receptor Antagonists; D000464:Alginates; D003692:Delayed-Action Preparations; D006603:Hexuronic Acids; D013607:Tablets; D019343:Citric Acid; D011092:Polyethylene Glycols; D020723:Glucuronic Acid; D017292:Doxazosin