Synthesis and characterization of Poly(N-Acryloyl 6-aminocaproic acid) for intestine-specific drug delivery

In this study, we investigated the feasibility of using poly(N-acryloyl 6-aminocaproic acid) (PA6ACA) as a pH-responsive polymer for oral enteric drug delivery. PA6ACA, characterized by its acylamino group, carboxyl group, and flexible 5-carbon chain, demonstrates pH sensitivity due to the presence of ionizable carboxyl groups and hydrogen bonding interactions between the carboxyl and amino moieties. Our research focused primarily on the preparation, characterization, and evaluation of enteric drugs delivered via PA6ACA. We evaluated the morphology, structure, thermal properties, and crystallinity of PA6ACA. Cytotoxicity experiments conducted in Caco-2 cells and the oral administration studies in mice provided preliminary safety evidence for PA6ACA. Three model drugs (budesonide, sulfasalazine, and diclofenac sodium) were employed to fabricate drug-polymer coprecipitates, and PA6ACA exhibited high loading capacities for these drugs. Furthermore, the drug release profiles revealed that the drug-loaded polymers were resistant to acid at pH 1.0 and nearly completely dissolved within the next 8 h at pH 6.8. The kinetic model fitting results indicated that the release of drugs from the coprecipitates were more consistent with the Higuchi model, suggesting minimal polymer swelling in the media and a primary drug release mechanism via diffusion. Based on these findings, we conclude that PA6ACA holds promise for the development of innovative and efficient intestine-specific drug delivery systems.