Effect of PLGA hydrophilia on the drug release and the hypoglucemic activity of different insulin-loaded PLGA microspheres

Abstract

The effects of viscosity and hydrophilic characteristics of different PLGA polymers on the microencapsulation of insulin have been studied in vitro and in vivo after subcutaneous administration to hyperglycemic rats. Hydrophilic PLGA polymers produced a higher burst effect than the hydrophobic ones. Moreover, an incomplete insulin release was observed with the hydrophilic PLGA polymers in comparison with the hydrophobic ones. An explanation for that incomplete release can be the development of polymer-insulin interactions associated to the polymer hydrophilic/hydrophobic character, as detected by DSC analysis. Differences in the release rate of microsphere formulations lead to differences in the hypoglycemic action and the weight of animals. Hydrophobic PLGA was able to prolong the hypoglycemic action up to 4 weeks which is at least double than that obtained with hydrophilic PLGA of a similar viscosity. Comparing insulin microspheres with an immediate release formulation, microspheres can increase insulin relative bioavailability up to four times.

Release mechanisms of tacrolimus-loaded PLGA and PLA microspheres and immunosuppressive effects of the microspheres in a rat heart transplantation model

“…A small molecule added to a polymer matrix usually acts as a plasticizer that diminishes intermolecular interaction of the polymer and depresses Tg of the mixture from Tg of the pure polymer (Freed, 2011). Therefore, we considered that the DSC results in this study indicated an interaction between tacrolimus and PLGA (Achim et al, 2008;Presmanes et al, 2011;Sanchez et al, 1993). Based on the results for the entrapment efficiency and DSC, hydrophobic interaction and hydrogen bonding would be important for the entrapment of tacrolimus in microspheres.…”

Aspirin‐/TMZ‐coloaded Microspheres Exert Synergistic Antiglioma Efficacy via Inhibition of β‐catenin Transactivation

“…Given the significance and clinical development potential of aspirin, we combined it with TMZ to assay the treatment efficacy. PLGA was selected to prepare aspirin, TMZ, and aspirin-/TMZloaded microspheres as it was widely used as a carrier of microspheres to parcel drugs and to lengthen their sustained release time in the pharmaceutical industry [29][30][31]. In this study, we compared the antitumor effect of PLGA-aspirin, PLGA-TMZ, and PLGA -aspirin-TMZ microspheres.…”

Multichamber PLGA Microparticles with Enhanced Monodispersity and Encapsulation Efficiency Fabricated by a Batch‐Microfluidic Hybrid Approach

“…[22,23] Despite the slightly hydrophilic nature of the PLGA polymer used in this study due to its acid-terminated structure, its overall hydrophobic character allows it to function as a W/O emulsifier. [24] Moreover, it is important to note that viscosity plays a crucial role in emulsion stability. The decrease in interfacial tension facilitates the formation of smaller emulsions due to the reduced stress required for droplet breakup (Figure 2c).…”