title: Differential scanning calorimetry and surface morphology studies on coated pellets using aqueous dispersions.
abstract: The present study was conducted to examine the physicochemical changes during passage of drug through polymeric membranes and observe the surface morphology features of the coated pellets using scanning electron microscopy (SEM). Drug solution was first sprayed around inert pellets to form drug-layered pellets that were coated with two commercial aqueous dispersions namely, Eudragit NE30 and Kollicoat SR30 using bottom-spray fluidized bed technique. Differential scanning calorimetry (DSC) confirmed that no interactions existed between drug and polymers. Small peak of drug was observed in the DSC thermograms of Eudragit NE30 coated pellets indicating that small amount of drug was still present in the polymeric membrane after dissolution. Views of SEM revealed as the coating levels of two types of aqueous dispersions were increased the surface of the pellets become more uniform and compact. Therefore, the diffusion length for dissolution medium to enter the drug layer and dissolved drug to diffuse out would be increased at higher coating levels. The polymer surface of coated pellets after 12 hours dissolution testing seemed to be shrunk and size of the pellets were also reduced indicating the depletion of reservoir layer.
authors.affiliation: Department of Pharmacy, Islamia University Bahawalpur, Pakistan. nisar60@yahoo.com
authors.lastname: Nisar-ur-Rahman
authors.forename: Yuen
authors.initials: Y
authors.lastname: K H
authors.forename: Wong
authors.initials: W
authors.lastname: Jia Woei
authors.forename: Nurzalina A k
authors.initials: NA
authors.lastname: Khan
mesh_terms: D002152:Calorimetry, Differential Scanning / Q000379:methods*; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003692:Delayed-Action Preparations / Q000737:chemistry* / Q000493:pharmacokinetics; D004058:Diffusion; D004110:Diltiazem / Q000737:chemistry / Q000493:pharmacokinetics; D004337:Drug Carriers / Q000737:chemistry / Q000493:pharmacokinetics; D004339:Drug Compounding / Q000379:methods; D016503:Drug Delivery Systems; D005079:Excipients / Q000737:chemistry; D008689:Methacrylates / Q000737:chemistry / Q000493:pharmacokinetics; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D011108:Polymers / Q000737:chemistry / Q000493:pharmacokinetics; D011109:Polymethacrylic Acids / Q000737:chemistry / Q000493:pharmacokinetics; D011145:Polyvinyls / Q000737:chemistry / Q000493:pharmacokinetics; D012995:Solubility; D013997:Time Factors; D044366:Transition Temperature; D014867:Water / Q000737:chemistry
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; C477853:Eudragit NE 30-D; C496967:Eudragit NE40D; D005079:Excipients; D008689:Methacrylates; D011108:Polymers; D011109:Polymethacrylic Acids; D011145:Polyvinyls; D014867:Water; C013215:polyvinyl acetate; D004110:Diltiazem