title: Diclofenac salts, part 6: release from lipid microspheres.
abstract: The release of diclofenac (20%, w/w) was studied from lipidic solid dispersions using three different chemical forms (acid, sodium salt, and pyrrolidine ethanol salt) and two different lipid carriers (Compritol 888 ATO or Carnauba wax) either free or together with varying amounts (10%-30%, w/w) of stearic acid. Microspheres were prepared by ultrasound-assisted atomization of the molten dispersions and analyzed by scanning electron microscopy, differential scanning calorimetry, and hot stage microscopy. The effects of different formulations on the resulting drug release profiles as a function of pH were studied and the results were discussed. The formulation of the 18 systems and the chemical form of the drug were found to strongly affect the mode of the drug release. The solubility of the chemical forms in the lipid mixture is in the following order: pyrrolidine ethanol salt ≫ acid > sodium salt (according to the solubility parameters), and the nature of the systems thus obtained ranges from a matrix, for mutually soluble drug/carrier pairs, to a microcapsule, for pairs wherein mutual solubility is poor. Drug release from microspheres prepared by pure lipids was primarily controlled by diffusion, whereas the release from microspheres containing stearic acid was diffusion/erosion controlled at pH 7.4.
authors.affiliation: Department SMETEC, University of Bologna, Bologna 40127, Italy. Electronic address: adamo.fini@unibo.it.
authors.forename: Adamo
authors.initials: A
authors.lastname: Fini
authors.affiliation: Department of Pharmaceutical Sciences, University of Bologna, Bologna 40126, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Cavallari
authors.affiliation: Department of Pharmacy and Pharmaceutical Technology, University of Seville, Seville 41012, Spain.
authors.forename: Antonio M
authors.initials: AM
authors.lastname: Rabasco Alvarez
authors.affiliation: Department of Pharmacy and Pharmaceutical Technology, University of Seville, Seville 41012, Spain.
authors.forename: Marisa Gonzalez
authors.initials: MG
authors.lastname: Rodriguez
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage* / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D004008:Diclofenac / Q000008:administration & dosage* / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry*; D004339:Drug Compounding; D005227:Fatty Acids / Q000737:chemistry; D005990:Glycerol / Q000031:analogs & derivatives; D006358:Hot Temperature; D008055:Lipids / Q000737:chemistry*; D008853:Microscopy; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D011092:Polyethylene Glycols; D012492:Salts; D012995:Solubility; D013229:Stearic Acids / Q000737:chemistry; D013499:Surface Properties; D013817:Thermography; D014885:Waxes / Q000737:chemistry
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D004337:Drug Carriers; D005227:Fatty Acids; D008055:Lipids; D012492:Salts; D013229:Stearic Acids; D014885:Waxes; C477262:compritol HD5 ATO; D004008:Diclofenac; C086409:glyceryl behenate; D011092:Polyethylene Glycols; C031183:stearic acid; D005990:Glycerol; C026344:carnauba wax