Elaboration of microparticles by the complex coacervation: Electro-kinetic study of associative mixtures and application to the encapsulation of an antalgic active ingredient

The main objective of this work is devoted to the microencapsulation process by the complex coacervation using two types of natural polymer namely sodium alginate and gelatin to encapsulate a pharmaceutical active ingredient of the “Diclofenac” family of analgesics and to prolong its release in vivo. In a first step, the influence of physicochemical parameters on the existing interactions between both polymers has been studied. The effects of pH, Pr : Ps (Protein: polysaccharide) ratio and the addition of salt concentration through the particle size and Zetametry by the dynamic light scattering technique, make it possible to experimentally limit the optimal domain of coacervate formation; which is used to formulate the Diclofenac-based microparticles. The results revealed a great influence of pH on the formation of the P r:Ps complex with an impact on the mean diameter (D42). The latter recorded a clear increase, with a decrease in the electro-kinetic potential reflecting the neutralization of the charges at pH 3.5-4. The results also showed a better coacervation (interaction between the polymers) for ratios of alginate / gelatin equal to 4/1 and 3/1. The formulation of microparticles based on Diclofenac by coacervation was subsequently characterized on the technical (size and texture) and biopharmaceutical levels, which revealed a prolonged type release of 8 h.