title: [Dissolution characteristics of composite particles using a spray freeze drying].
abstract: A spray freeze drying (SFD) method, using a spray nozzle, liquid N(2) and a lyophilizer, was developed to prepare composite particles of a poorly water-soluble drug. The resultant particles were found to have a porous structure. The purpose of the present research was to prepare a sustained release formulation using the SFD technique. Tolbutamide (TBM)and Eudragit S were used as model drugs and pH-dependent carrier, respectively. Eudragit S is a polymer that is soluble at or above pH 7.0. Morphological evaluation of the composite particles revealed that they had a porous structure with a significantly larger specific surface area than bulk TBM. The physicochemical properties of the particles were found to be dependent on the drug to carrier ratio, with the crystallinity of the TBM decreasing as the proportion of Eudragit S increased. Dissolution tests in solutions of pH 1.2 and pH 6.8 showed that the release profiles of TBM from the SFD composite particles were improved compared to bulk TBM, through the use of the pH-dependent carrier. On the other hand, following compression of the composite particles, sustained release was observed in a solution of pH 6.8, whereas almost no dissolution occurred in a solution of pH 1.2.
authors.affiliation: Faculty of Pharmacy, Meijo University, Nagoya, Japan. ma_kondoh@skk-net.com
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kondo
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Niwa
authors.forename: Kazumi
authors.initials: K
authors.lastname: Danjo
mesh_terms: D002627:Chemistry, Physical; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D005612:Freeze Drying / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D010316:Particle Size; D011108:Polymers; D011109:Polymethacrylic Acids; D016062:Porosity; D012995:Solubility; D014044:Tolbutamide; D014867:Water
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; D011108:Polymers; D011109:Polymethacrylic Acids; D014867:Water; C038300:methylmethacrylate-methacrylic acid copolymer; D014044:Tolbutamide