Self-organized drug-interpolyelectrolyte nanocomplexes loaded with anionic drugs. Characterization and in vitro release evaluation

Abstract

The current study is focused on physicochemical characterization and in vitro drug delivery evaluation ofself-organized nanoparticles based on drug-interpolyelectrolyte complexes (DIPEC). The interactionbetween two oppositely charged polymethacrylates, Eudragit® EPO and L100, and four non-steroidalanti-inflammatory drugs, Salicylic Acid, Benzoic Acid, Ketoprofen and Naproxen was studied.DIPEC nanoparticles produce translucent and stable aqueous dispersions where a remarkably highproportion of drug (between 57 and 95%) is condensed with polyelectrolyte (PE) under the form of ionicpairs. They exhibited particle size in the range of 120e198 nm and high positive zeta potential,contributing to physical stability. The sign of zeta potential shifted from positive to negative by changesin composition of DIPEC. Thermal analysis and X-ray diffraction patterns of freeze dried DIPEC showedthe amorphous state of products and the complete interaction of PE and drug. Solid complexes wereeasily redispersed in water yielding nearly the same parameters of fresh dispersions. In vitro releaseexperiments showed that DIPEC nanodispersions behave as drug reservoirs, exhibiting a slow drugrelease rate in water, which significantly increased in simulating physiological fluids, promoted by ionicexchange. They also exhibited a remarkable robustness towards simulated physiological media ofdifferent pH.