Recent formulation approaches to oral delivery of herbal medicines

The well-known anticancer agent, paclitaxel, is a naturally occurring diterpenoid from Taxus brevifolia . It is an effective antineoplastic agent that has been widely used for the treatment of various cancers, including breast, ovarian, and lung cancers. One of the major limitations for the therapeutic use of herbal medicines is low solubility. Moreover, despite their potential efficacy, herbal medicinal products have been widely criticized due to a lack of standardization and poor apparent quality. In the case of herbal extracts, many compounds could be degraded in the highly acidic pH of the stomach. Other ingredients could be metabolized in the liver before reaching the systemic circulation. In addition, herbal extracts are often poorly compressible and very hygroscopic powders with poor powder flowability. As herbal drugs have much potential, several researchers are trying to develop novel drug delivery systems, such as solid dispersion, fast-dissolving tablets, sustained—and extended-release formulations, microparticles, microcapsules, nanoparticles, and mucoadhesive systems. This review provides an overview of existing pharmaceutical systems of herbal medicines and recent techniques to overcome the drawbacks of conventional formulations that result in reduced efficacy of herbal medicines.