title: The effect of formulation variables on the characteristics of insulin-loaded poly(lactic-co-glycolic acid) microspheres prepared by a single phase oil in oil solvent evaporation method.
abstract: Biodegradable polymeric microspheres are ideal vehicles for controlled delivery applications of drugs, peptides and proteins. Amongst them, poly(lactic-co-glycolic acid) (PLGA) has generated enormous interest due to their favorable properties and also has been approved by FDA for drug delivery. Insulin-loaded PLGA microparticles were prepared by our developed single phase oil in oil (o/o) emulsion solvent evaporation technique. Insulin, a model protein, was successfully loaded into microparticles by changing experimental variables such as polymer molecular weight, polymer concentration, surfactant concentration and stirring speed in order to optimize process variables on drug encapsulation efficiency, release rates, size and size distribution. A 2(4) full factorial design was employed to evaluate systematically the combined effect of variables on responses. Scanning electron microscope (SEM) confirmed spherical shapes, smooth surface morphology and microsphere structure without aggregation. FTIR and DSC results showed drug-polymer interaction. The encapsulation efficiency of insulin was mainly influenced by surfactant concentration. Moreover, polymer concentration and polymer molecular weight affected burst release of drug and size characteristics of microspheres, respectively. It was concluded that using PLGA with higher molecular weight, high surfactant and polymer concentrations led to a more appropriate encapsulation efficiency of insulin with low burst effect and desirable release pattern.
authors.affiliation: Pharmaceutical Technology Laboratory, Drug Applied Research Center, Tabriz University (Medical Sciences), Tabriz, Iran.
authors.forename: Hamed
authors.initials: H
authors.lastname: Hamishehkar
authors.forename: Jaber
authors.initials: J
authors.lastname: Emami
authors.forename: Abdolhossein Rouholamini
authors.initials: AR
authors.lastname: Najafabadi
authors.forename: Kambiz
authors.initials: K
authors.lastname: Gilani
authors.forename: Mohsen
authors.initials: M
authors.lastname: Minaiyan
authors.forename: Hamid
authors.initials: H
authors.lastname: Mahdavi
authors.forename: Ali
authors.initials: A
authors.lastname: Nokhodchi
mesh_terms: D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D002850:Chromatography, Gel; D004339:Drug Compounding; D016503:Drug Delivery Systems; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D019344:Lactic Acid / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D008970:Molecular Weight; D009821:Oils / Q000737:chemistry*; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D012997:Solvents / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014835:Volatilization; D014961:X-Ray Diffraction
chemical_list: D007328:Insulin; D009821:Oils; D012997:Solvents; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid