title: Rupture and drug release characteristics of multi-reservoir type microspheres with poly(dl-lactide-co-glycolide) and poly(dl-lactide).
abstract: For the multi-reservoir type microspheres composed of polylactide (PLA) and poly(dl-lactide-co-glycolide) (PLGA), the influence of inner drug-holding layer/outer layer ratio on drug release profiles was studied. The microspheres were prepared by the O/W type emulsion-solvent evaporation technique, and cisplatin was used as a model drug. The water-uptake and the erosion of each polymer were evaluated to clarify the mechanism of drug release for multi-reservoir type microspheres. The formulations were classified by the influence of the blending ratio on drug-release profiles: the formulations with the drug-release profiles independent of the blending ratio (Typel group) and the formulations with drug-release profiles depending on the blending ratio (type 2 group). The formulations of type 1 group showed the uniform swelling during drug-release test, and provided the drug-release governed by the erosion of the inner drug-holding layer. On the other hand, the formulations of Type2 group showed the rupture of outer layer which was induced by the swelling of inner drug-holding layer, and the microspheres with the low ratio of the PLGA provided the drug-release rate which exceeded the estimate from the erosion profiles. The results of present study revealed that two types of drug-release mechanism exist for multi-reservoir type microspheres.
authors.affiliation: Pharamaceutical Development Laboratory, Tanabe Seiyaku Co. Ltd., Kashima 3-chome, Yodogawa-ku, Osaka 532, Japan. pinebook@tanabe.co.jp
authors.forename: Akihiro
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Matsukawa
authors.forename: Yuji
authors.initials: Y
authors.lastname: Horikiri
authors.forename: Takehiko
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D002626:Chemistry, Pharmaceutical; D002945:Cisplatin / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry*; D008863:Microspheres; D011091:Polyesters / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*
chemical_list: D011091:Polyesters; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide); D002945:Cisplatin