title: Influence of pH on the release of propranolol hydrochloride from matrices containing hydroxypropylmethylcellulose K4M and carbopol 974.
abstract: The dissolution of propranolol hydrochloride from matrices containing hydroxypropylmethylcellulose K4M (HPMC K4M) and carbopol 974 has been investigated using 0.1 M hydrochloric acid or phosphate buffer at pH 4.5 or pH 7.5. In 0.1 M hydrochloric acid, HPMC K4M predominantly controlled release since carbopol has a low solubility at this pH. As the pH increased, the carbopol became increasingly ionized and interacted with propranolol hydrochloride to form an insoluble complex which retarded the release of the drug. In addition, the nature of the interaction between carbopol 974 and HPMC K4M altered. DSC and viscometric studies indicated that the two polymers contributed synergistically to the gel network at pH 7.5. Thus at pH 7.5 polymers contributed to matrix integrity and to the control of drug release.
authors.affiliation: School of Pharmacy and Chemistry, Liverpool John Moores University, UK.
authors.forename: B
authors.initials: B
authors.lastname: Perez-Marcos
authors.forename: J L
authors.initials: JL
authors.lastname: Ford
authors.forename: D J
authors.initials: DJ
authors.lastname: Armstrong
authors.forename: P N
authors.initials: PN
authors.lastname: Elliott
authors.forename: C
authors.initials: C
authors.lastname: Rostron
authors.forename: J E
authors.initials: JE
authors.lastname: Hogan
mesh_terms: D000180:Acrylic Resins; D006863:Hydrogen-Ion Concentration; D011108:Polymers / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry*; D011433:Propranolol / Q000737:chemistry*; D011480:Protease Inhibitors / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D011108:Polymers; D011145:Polyvinyls; D011480:Protease Inhibitors; C006912:carboxypolymethylene; D011433:Propranolol