Engineered Site-specific Vesicular Systems for Colonic Delivery: Trends and Implications

Abstract

Steering drug-loaded, site-specific, coated lipid vesicles to the target receptor sites have the potential of plummeting adverse effects and improving the pharmacological response in diverse pathologies of the large bowel, especially the colon. Colonic delivery via oral route has its own challenges, often governed by several glitches such as drug degradation or absorption in the upper GIT, instability of proteins/peptides due to high molecular weight, and peptidase activity in the stomach. Consequently, colon-specific coated liposomal systems (CSLS) offer a potential alternate for not only site-specificity, but protection from proteolytic activity, and prolonged residence time for greater systemic bioavailability. On the other hand, liposomal delivery via the oral route is also cumbersome owing to several barriers such as instability in GIT, difficulty in crossing membranes, and issues related to production at the pilot scale. New advancements in the field of CSLS have successfully improved the stability and permeability of liposomes for oral delivery via modulating the compositions of lipid bilayers, adding polymers or ligands. Despite this ostensible propitiousness, no commercial oral CSLS has advanced from bench to bedside for targeted delivery to the colon as yet. Nevertheless, CSLS has quite fascinated the manufacturers owing to its potential industrial viability, simplistic and low-cost design. Hence, this review aims to decipher the convolutions involved in the engineering process of industrially viable CSLS for colonic delivery.

Keywords: Coated liposomes; active targeting; colon drug delivery; colon specific liposomal systems (CSLS); immunoliposomes; nanoliposomes; phytochemicals.