Liposomes for Herbal Drug Delivery

This chapter evaluates liposomes used as delivery carriers for herbal products, which, due to poor permeability and solubility of extract components, has become a major issue in phytotherapy for treating illnesses and human health problems. Liposomes are vesicular formations with phospholipid bilayers that possess the capability to entrap both water-soluble and hydrophobic substances. However, there are several factors that should be considered with regard to herbal drugs, especially that the preparation technique should be appropriate to the solvent solubility of the plant extracts. In this regard, the ratio of phospholipids to extracts, pH stability, other liposomal components, and the ligand required to render liposome stability, circulation in the bloodstream for protracted periods, and targeted at specific organs should be investigated. The enhancement of phytochemical constituent stability within a context of environmental, physical, and chemical degradation, together with sustained or controlled drug release, can be achieved by incorporating extracts into liposomes. Moreover, the improved oral absorption of plant extracts by encapsulating them into liposomes indicates increased permeability and bioavailability via gastrointestinal tracts, thus enhancing pharmacological effects at low dose concentration as well as decreasing toxicity. However, thousands of constituents contained in plant extracts demonstrate various physicochemical characteristics that constitute significant challenges for liposomal delivery. Consequently, a comprehensive analysis of formulating and manufacturing aspects is required.