title: The effect of gamma-irradiation on drug release from bioerodible microparticles: a quantitative treatment.
abstract: The two major objectives of this study were: (i) to monitor the effect of different gamma-irradiation doses (4-33 kGy) on the release kinetics from 5-fluorouracil (5-FU)-loaded poly(D,L-lactide-co-glycolide) (PLGA)-based microparticles, and (ii) to analyze the obtained experimental data with a new mathematical model giving insight into the occurring mass transport phenomena. Drug release was found to depend significantly on the applied gamma-irradiation dose. Interestingly, the obtained release profiles were all biphasic: a rapid initial drug release phase ("burst") was followed by a slower, approximately constant drug release phase. Surprisingly, only the initial rapid drug release was accelerated by gamma-irradiation; the subsequent zero-order phase was almost unaffected. Importantly, the new mathematical model which is based on Fick's second law of diffusion and which considers polymer degradation was applicable to all the investigated systems. In addition, the gamma-irradiation dose could be quantitatively related to the resulting drug release rate. In conclusion, diffusion seems to be the dominating release rate controlling mechanism in all cases, with a significant contribution of the polymer degradation process.
authors.affiliation: INSERM ERIT-M 0104, Université d'Angers, 10 rue André Boquel, 49100, Angers, France.
authors.forename: N
authors.initials: N
authors.lastname: Faisant
authors.forename: J
authors.initials: J
authors.lastname: Siepmann
authors.forename: P
authors.initials: P
authors.lastname: Oury
authors.forename: V
authors.initials: V
authors.lastname: Laffineur
authors.forename: E
authors.initials: E
authors.lastname: Bruna
authors.forename: J
authors.initials: J
authors.lastname: Haffner
authors.forename: J
authors.initials: J
authors.lastname: Benoit
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000737:chemistry / Q000528:radiation effects; D004058:Diffusion; D005079:Excipients / Q000528:radiation effects*; D005472:Fluorouracil / Q000737:chemistry / Q000528:radiation effects; D005720:Gamma Rays; D007700:Kinetics; D019344:Lactic Acid; D008863:Microspheres; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000528:radiation effects*; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers
chemical_list: D000964:Antimetabolites, Antineoplastic; D005079:Excipients; D004364:Pharmaceutical Preparations; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D005472:Fluorouracil