Research status and cutting-edge advances in PEO applications for oral drug delivery systems

Regulating the release of drugs precisely is one of the most important aspects of oral drug delivery systems (ODDSs). There are many formulations and preparation techniques for solving this problem, the most widely used is the application of hydrophilic polymers. Due to its high swelling rate, semi crystallinity and wide molecular weight (MW) range, Polyethylene Oxide (PEO) stands out among hydrophilic polymers. PEO is derived from the ring opening polymerization reaction of epoxyethane. When regulating oral drug release, the strength of the gel layer formed when it meets water can be adjusted by replacing different MW PEO, changing the concentration of PEO and other methods, thus affecting the release of the active pharmaceutical ingredients (APIs) in the tablet. However, with the development of its applications, it has also been found that PEO has certain limitations in regulating drug release, such as its mucosal adhesion is insufficient, low molecular weight PEO (LMW-PEO) may experience burst release, the improper use of high molecular weight PEO (HMW-PEO) may result in excessive hardness of tablets prepared therefrom, leading to delayed disintegration upon contact with the medium and consequently affecting the drug release rate. This review summarizes the factors affecting the hydrodynamics of PEO gel, including its molecular weight and concentration, environment's pH, the introduction of other polymers or additives. Then, some ideas have been proposed to address these application limitations, laying the foundation for the wider application of PEO in the future.