Monday, July 6, 2015

PLGA-Protein microparticles for long-term medicinal delivery

PolySciTech ( provides a wide variety of PLGA and related biodegradable polymers. One of the uses for this type of polymer is to generate biodegradable microparticles which contain medicine that slowly leaches out of the particles over the course of time (typically 1 to 6 months depending on formulation) so that this can be administered as long-acting injections. Recently a research article has been published in which the various parameters for generating protein loaded PLGA microparticles were optimized. This research has promise for the development of long-acting protein drug based injections which can be applied to many diseases. For example, proteins such as insulin is used to treat diabetes, infliximab is used to treat Crohns disease/arthritis, rituximab is used to treat lymphoma/leukemia and cetuximab is used to colorectal cancer. Use of PLGA-protein microparticles could one day provide for long-acting versions of these injected medicines. Read more: Martín-Sabroso, C., A. I. Fraguas-Sánchez, J. Aparicio-Blanco, M. F. Cano-Abad, and A. I. Torres-Suárez. "Critical attributes of formulation and of elaboration process of PLGA-protein microparticles." International journal of pharmaceutics 480, no. 1 (2015): 27-36.

“Abstract: Low drug loading, burst effect during release and drug inactivation account for the main drawbacks of protein microencapsulation in poly(d,l-lactic-co-glycolic) acid (PLGA) matrix by the water-in oil-in water (W/O/W) solvent evaporation method. Thus, the current study was set to invest the critical attributes of formulation and of elaboration process which determine protein loading into microparticles as well as its further release, using albumin as protein model. NaCl concentration in the external aqueous phase, poly(vinyl alcohol) (PVA) concentration and mostly viscosity of both the internal aqueous phase and the organic phase were critical attributes for improving drug loading, with polymer molecular weight and hydrophobicity likewise directly related to albumin loading. In such a way, when using 0.5% PVA as internal aqueous phase the highest albumin loading was achieved. Optimized microparticles exhibited a sustained in vitro release of albumin over 130 days. The influence of the microencapsulation process on albumin stability and biological activity was evaluated by carrying out cell proliferation assays on PC12 cells with albumin released from microparticles. Such assay demonstrated that the microencapsulation procedure optimized in this study did not affect the biological stability of the microencapsulated protein. Abbreviations: ALB, albumin; BCA, bicinchoninic acid; BSA, bovine serum albumin; DCM, dichloromethane; DMEM, Dulbecco’s modified Eagle’s medium; DMSO, dimethylsulfoxide; MP, microparticles; OD, optical density; PAO, phenylarsine oxide; PBS, phosphate buffered saline; PEG, poly(ethylene glycol); PLGA, poly(d,l-lactic-co-glycolic) acid; PVA, poly(vinyl alcohol); SEM, scanning electron microscopy; SPARC, secreted protein acidic and rich in cysteine; W/O/W, water-in oil-in water Keywords: Protein microencapsulation; Albumin; Microparticles; Quality by design; Critical attributes; Poly(lactic-co-glycolic) acid”

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