Influence of a non-ionic poloxamer surfactant, Pluronic F68, on protein release from poly(methylidene malonate 2.1.2) microparticles in simulated gastric and intestinal media

We recently described a new microparticulate system based on poly(methylidene malonote 2.1.2). This paper focuses on an in vitro evaluation of this system for oral administration. Degradation studies, achieved in simulated gastric and intestinal media, have shown that size distribution and polymer molecular weight were not modified over an 8-h incubation period, confirming that such microparticles are suitable for oral administration. Ovalbumin release in these same media was very fast, with 90% released after 2 h. This release was attributed to the degradation of surface-bound protein, the distribution of which at the microparticle surface was confirmed by confocal microscopy. The addition of Pluronic F68 to the internal phase promoted ovalbumin location inside the internal globules, leading to a diminished release it? the same media. Almost 40,70 of ovalbumin can be considered as protected against degradation when Pluronic is added to the formulation. Therefore, a clear correlation was established between the modification of protein location within microparticles by Pluronic F68 and protection against degradation in simulated digestive media.