Purpose. To develop and characterize a novel composite alginate/PLGA microparticulate system for peptide and protein delivery. Human and bovine insulin were used as model drugs. Methods. Human and bovine insulin stability at 37°C was evaluated in 0.1M phosphate buffer (pH 7.4) and in 10mM glycine buffer (pH 2.8), respectively. Humalog® adsorption behavior on blank alginate, blank PLGA, and composite microparticles was investigated as well. Alginate particles were prepared by ionic gelation and embedded into PLGA polymeric matrix by a solvent diffusion evaporation method. Actual loading was determined by micro-BCA protein assay (total insulin) and by RPHPLC (native insulin). RP-HPLC analysis were carried out in an isocratic manner (1 ml/min at 40°C) using 74% of 0.2M sulphate buffer pH 2.3 and 26% acetonitrile as a mobile phase. In vitro release studies were carried out as well. Results. Bovine insulin resulted less stable than human insulin, probably because of the presence of additives in Humalog® solution. Indeed, 55 and 20% of bovine and human insulin were lost after 7 days, respectively. Humalog® did not show any significant adsorption on all microparticles kinds. Bovine and human insulin loaded composite microparticles showed a reproducible encapsulation efficiency of 38 and 67%, respectively. The percentage active peptide determined by HPLC was ~43 for bovine insulin and ~60% for the human one. Using a conventional double emulsion method, only about 9 (bovine) and 27% (human) of the peptide was found to be in the native form after encapsulation. In vitro release studies showed a low burst effect (12%) in the case of bovine insulin, while, probably due to the plasticizing effect of the additives, 50% of the Humalog® was released from the particles the first day. Conclusion. Alginate showed a good protective effect on insulin and allowed to increase the encapsulation efficiency. Further studies are in progress to improve insulin release profile.

Preparation and characterization of a novel composite alginate/PLGA microparticulate system for peptide and protein delivery

SCHOUBBEN, Aurelie Marie Madeleine;BLASI, PAOLO;GIOVAGNOLI, Stefano;RICCI, Maurizio;ROSSI, Carlo
2007

Abstract

Purpose. To develop and characterize a novel composite alginate/PLGA microparticulate system for peptide and protein delivery. Human and bovine insulin were used as model drugs. Methods. Human and bovine insulin stability at 37°C was evaluated in 0.1M phosphate buffer (pH 7.4) and in 10mM glycine buffer (pH 2.8), respectively. Humalog® adsorption behavior on blank alginate, blank PLGA, and composite microparticles was investigated as well. Alginate particles were prepared by ionic gelation and embedded into PLGA polymeric matrix by a solvent diffusion evaporation method. Actual loading was determined by micro-BCA protein assay (total insulin) and by RPHPLC (native insulin). RP-HPLC analysis were carried out in an isocratic manner (1 ml/min at 40°C) using 74% of 0.2M sulphate buffer pH 2.3 and 26% acetonitrile as a mobile phase. In vitro release studies were carried out as well. Results. Bovine insulin resulted less stable than human insulin, probably because of the presence of additives in Humalog® solution. Indeed, 55 and 20% of bovine and human insulin were lost after 7 days, respectively. Humalog® did not show any significant adsorption on all microparticles kinds. Bovine and human insulin loaded composite microparticles showed a reproducible encapsulation efficiency of 38 and 67%, respectively. The percentage active peptide determined by HPLC was ~43 for bovine insulin and ~60% for the human one. Using a conventional double emulsion method, only about 9 (bovine) and 27% (human) of the peptide was found to be in the native form after encapsulation. In vitro release studies showed a low burst effect (12%) in the case of bovine insulin, while, probably due to the plasticizing effect of the additives, 50% of the Humalog® was released from the particles the first day. Conclusion. Alginate showed a good protective effect on insulin and allowed to increase the encapsulation efficiency. Further studies are in progress to improve insulin release profile.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11391/32791
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