Recently, therapeutic proteins have been used to combat life-threatening diseases. To date, oral routes have been developed to deliver proteins. Since the proteolytic degradation in the upper gastrointestinal tract frequently occurs, we need a formulation and strategy to protect and deliver protein to the colon. In this research, solid lipid nanoparticles (SLNs) were prepared in eight formulae for colon-targeted delivery with various glyceryl monostearate, Tween 80, soy lecithin, and polyethylene glycol 6000 concentrations. Bovine serum albumin (BSA) was used for the protein model in the system. All formulae were characterized by their morphology, particle size, polydispersity index (PDI), zeta potential, and entrapment efficiency. The distribution of particle sizes varied between 94.24 and 186.8 nm and the zeta potential value ranged from −22.8 to −34.3 mV. Formula 4 (F4) showed the best entrapment efficiency of 78.69% with a particle size of 102.1 nm, PDI of 0.349, and zeta potential of −26.1 mV. F4 was then coated with Eudragit S100 and measured for its drug release profile in vitro. F4 coated with Eudragit S100 held the drug released in the gastric and released all the BSA in the colon condition. These results indicated that BSA-SLN F4 could be a promising delivery system to obtain optimal colon-targeted parameters.

Colon-targeted drug delivery systems have been exploited to treat local diseases in the colon, systemic delivery of protein and peptide, and chronotherapeutic drugs. The upper gastrointestinal tract restricts the effective delivery of these drugs. Therefore, several strategies are needed for targeted drugs directly to the colon, such as pH-sensitive polymers, enzyme-sensitive polymers, bacterially degradable polysaccharides, time-dependent polymers, and particulate systems. However, variable physiological conditions of the gastrointestinal tract in individuals cause combinations of these strategies are needed to ensure colonic delivery of the drug. This review presents and discusses several potential drugs and their approaches used to design and develop colon-targeted drug delivery systems for medications with particular characteristics.