Effect of Formulation Parameters and Physiological Environment on Amlodipine Release Kinetics Encapsulated in Biodegradable Polymers and Optimized by Design Methodology

Abstract

In this study, two polyelectrolytes, chitosan and propyl methyl cellulose carbonate, were associated by crosslinking with tripolyphosphate (TPP), to prepare microspheres loaded with amlodipine besylate (Aml). The formulations were optimized by Box–Behnken experimental design, in which three factors, four responses were studied to check the effect of independent variables (concentration of TPP, pH of TPP solution, and pH of a polymer mixture) on responses: zeta potential, particle size, polydispersity index and entrapment efficiency. The optimal encapsulation efficiency was around 92.43%, the zeta potential on average 41.75 mV, and the minimum mean particle size was 310 nm. The effects of the parameters on changes in structure, crystallinity, and surface charges of polymers, by crosslinking in microparticles, were identified by FT-IR, XRD, and dynamic light scattering analyses. The encapsulation parameters and the environment media influenced the mechanism of release and the kinetics model, which was greater in the duodenal medium at pH 5.5 (Q = 100%). The microencapsulation by nontoxic polymers in water is a good method of preparing amlodipine-loaded microspheres, which are intended for the oral route, with optimal dose release in the duodenal medium. This represents the target site for absorption of the drug, in the pulmonary sphere.