title: Influence of poly (lactide-co-glycolide) type and gamma irradiation on the betamethasone acetate release from the in situ forming systems.
abstract: In situ forming biodegradable polymeric systems were prepared from Poly (DL-lactide-co-glycolide), RG504H (50:50, lactide:glycolide), RG756 (75:25) and mixture of them. They were dissolved in N-methyl-2-pyrrolidone (33% w/w) and mixed with betamethasone acetate (BTMA, 5 and 10% w/w) and ethyl heptanoate (5% w/w, as an additive). The effects of gamma irradiation, drug loading, type of polymers and solvent removal were evaluated on release profiles. Scanning electron microscopy (SEM) of RG756 samples loaded by BTMA did not show any degradation until two weeks. Differential scanning calorimeter (DSC) experiments confirmed insignificant decrease in T(g), and consequently release rate. Declining T(g) of RG504H and RG756 after gamma irradiation was about 0.4 and 1.46 degrees C, respectively. High performance liquid chromatography (HPLC) revealed that BTMA release is more rapid from the formulations prepared using the RG504H with lower molecular weight. The formulations prepared by RG756 had lower burst release (2.5-41%) than the samples based on RG504H (60-67%) and mixture of them (30-33%). Regarding this research three different kinds of steriled in situ forming systems were developed which can release BTMA for 24, 90 and 60 days.
authors.affiliation: Medical Physics and BioMedical Engineering Department, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81744-176, Iran. m_rafienia@med.mui.ac.ir
authors.forename: Mohammad
authors.initials: M
authors.lastname: Rafienia
authors.forename: Shahriar Hojjati
authors.initials: SH
authors.lastname: Emami
authors.forename: Hamid
authors.initials: H
authors.lastname: Mirzadeh
authors.forename: Hamid
authors.initials: H
authors.lastname: Mobedi
authors.forename: Saeed
authors.initials: S
authors.lastname: Karbasi
mesh_terms: D001623:Betamethasone / Q000008:administration & dosage* / Q000031:analogs & derivatives / Q000493:pharmacokinetics*; D001682:Biological Availability; D002152:Calorimetry, Differential Scanning; D004343:Drug Implants / Q000737:chemistry / Q000528:radiation effects; D005720:Gamma Rays; D006537:Heptanoates / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D016062:Porosity; D011760:Pyrrolidinones / Q000737:chemistry; D013499:Surface Properties; D013818:Thermogravimetry
chemical_list: D004343:Drug Implants; D006537:Heptanoates; D011760:Pyrrolidinones; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C032206:ethyl oenanthate; D001623:Betamethasone; C038678:N-methylpyrrolidone