The β- and γ-irradiation effects on stability of microspheres made of poly(lactide-co-glycolide) 50:50 copolymer (PLGA) containing bupivacaine (BU) were studied. Microspheres containing 10, 25, and 40% w/w, respectively, of BU were prepared by spray drying and irradiated in air with β- and γ-irradiation at a dose of 25 kGy. Morphology (atomic force microscopy, particle-size analysis), physico-chemical characteristics (DSC and FT-IR spectroscopy), drug content and in vitro dissolution profile of microspheres were all determined; the stability of irradiated microspheres was evaluated over a 9-month period. The decrease of BU content in γ-irradiated microspheres was almost always constant independent of the amount of BU per sample, therefore it was in inverse proportion to drug loading (range between 5 and 15%). BU release rate increased immediately after irradiation and increased slightly until 90 days of storage. As far as β-irradiated microspheres are concerned, BU content decreased in a significant way (≈3%) only in microspheres containing 10% w/w of BU. Immediately after irradiation, drug release rate in β-irradiated microspheres increased less than in the corresponding γ-irradiated microspheres, and it did not change further over the following storage period. BU-loaded microspheres have been shown to be more stable against β- than γ-irradiation. AFM revealed that the surface roughness of the irradiated microspheres increases depending on irradiation. As such, if a parameter is quantifiable, it is proposed as a marker of degradation due to ionizing radiation
Poly(lactide-co-glycolide) microspheres containing bupivacaine: comparison between gamma and beta irradiation effects / L. Montanari, F. Cilurzo, F. Selmin, B. Conti, I. Genta, G. Poletti, F. Orsini, L. Valvo. - In: JOURNAL OF CONTROLLED RELEASE. - ISSN 0168-3659. - 90:3(2003 Jul 31), pp. 281-290.
Poly(lactide-co-glycolide) microspheres containing bupivacaine: comparison between gamma and beta irradiation effects
L. MontanariPrimo
;F. CilurzoSecondo
;F. Selmin;G. Poletti;F. OrsiniPenultimo
;
2003
Abstract
The β- and γ-irradiation effects on stability of microspheres made of poly(lactide-co-glycolide) 50:50 copolymer (PLGA) containing bupivacaine (BU) were studied. Microspheres containing 10, 25, and 40% w/w, respectively, of BU were prepared by spray drying and irradiated in air with β- and γ-irradiation at a dose of 25 kGy. Morphology (atomic force microscopy, particle-size analysis), physico-chemical characteristics (DSC and FT-IR spectroscopy), drug content and in vitro dissolution profile of microspheres were all determined; the stability of irradiated microspheres was evaluated over a 9-month period. The decrease of BU content in γ-irradiated microspheres was almost always constant independent of the amount of BU per sample, therefore it was in inverse proportion to drug loading (range between 5 and 15%). BU release rate increased immediately after irradiation and increased slightly until 90 days of storage. As far as β-irradiated microspheres are concerned, BU content decreased in a significant way (≈3%) only in microspheres containing 10% w/w of BU. Immediately after irradiation, drug release rate in β-irradiated microspheres increased less than in the corresponding γ-irradiated microspheres, and it did not change further over the following storage period. BU-loaded microspheres have been shown to be more stable against β- than γ-irradiation. AFM revealed that the surface roughness of the irradiated microspheres increases depending on irradiation. As such, if a parameter is quantifiable, it is proposed as a marker of degradation due to ionizing radiationPubblicazioni consigliate
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