Nanotechnology-Based Drug Delivery of Phytotherapeutics: Herbal Drugs and Nanotechnology

Introduction

World Health Organization reports that 80% of the developing countries population depend on traditional medicinal practices to meet and / or supplement their basic health needs. (Verma & Singh, 2008) Currently, despite marketing and encouragement from the pharmaceutical industry during the development of allopathic medicines, a large segment of the population in many countries continues to utilize complementary practices for their health care. Many of these practices are derived from medicinal plants. However, due to economic, political, and social changes that have occurred worldwide, the therapeutic use of these natural resources, which are mainly used by people who cannot afford different treatments, has greatly diminished. (Goyal et al., 2011)

The biological activity of medicinal plants from all over the world has been studied by several groups of researchers. These studies are based on the popular uses of different species, as well as on popular knowledge and scientific studies describing medical plant use, with a focus on how these plants could benefit the pharmaceutical industry. (Kesarwani et al., 2013). Approximately 50% of the drugs approved during 1981–2006 were directly or indirectly derived from natural products. The chemical complexity of extracts is an extremely important consideration for the success of a formulation, because the formulation must also release the active ingredient. Consequently, vehicles must concurrently improve the solubility of the drug, minimize the degradation process, reduce any toxicity, and mask any bad taste, while controlling the active absorption and biological response. (Holmberg et al., 2002)

Phytochemical and phytopharmacological sciences have already established the composition and biological activities of several medicinal plant products. Most of the biologically active constituents of extracts, such as flavonoids, tannins, and terpenoids, are highly water-soluble, but demonstrate a low absorption, because they are unable to cross lipid membranes, have high molecular sizes, and demonstrate poor absorption, resulting in loss of bioavailability and efficacy. (Mainardes et al., 2006). Studies have shown that herbal medicines have good activity in assays in vitro, which are not reproducible in experiments in vivo. Furthermore, some essential substances are rarely used, because they are incompatible with other components in the formulation or have undesirable properties. (Grill et al., 2009)

Hence, phytotherapeutics need a scientific approach to deliver the components in a sustained manner to increase patient compliance and avoid repeated administration. This can be achieved by designing novel drug delivery systems (NDDS) for herbal constituents. (Yadav et al., 2011) NDDS reduce the repeated administration thereby overcoming non-compliance and help increase the therapeutic value by reducing toxicity and increasing bioavailability. One such novel approach is nanotechnology. Nano-sized drug delivery systems of herbal drugs have a potential future for enhancing the activity and overcoming problems associated with plant medicines (Singh et al., 2011). Nanotechnology offers multiple benefits in treating chronic human diseases by site-specific and target-oriented delivery of precise medicines. Recently, there are several outstanding applications of nanomedicine (chemotherapeutic agents, biological agents, immunotherapeutic agents, etc.) in the treatment of various diseases. (Sahni et al., 2011)

Pharmaceutical industries also have become increasingly interested in nanotechnological advances because these developments provide advantages, such as modified release systems, and the potential to develop new formulations that were previously not possible (due to several aspects related to the active constituents). Although nanotechnology contributions are advantageous for several medicinal areas, it is essential to highlight some of the disadvantages. Clinical researchers have mentioned some negative factors, such as high cost, difficulty of scaling up processes, and the ease of inhalation of nanoparticles, which can result in dangerous lung diseases, and often lead to other diseases that can lead to changes in homeostasis, or even death. The strategy of applying nanotechnology to plant extracts has been widely cited in literature, because nanostructured systems could potentiate action of plant extracts, promote sustained release of active constituents, reduce the required dose, decrease side effects, and improve activity. (Lee et al., 2010)