ABSTRACT
Herbal and ayurvedic medicines are the oldest medicines in human society. From the beginning of civilization, herbal medicines were used to treat human diseases as much as possible (DeSmet 1997). The World Health Organization (WHO) has dened herbal medicines as nished, labeled medicinal products that contain active ingredients, aerial or underground parts of plants or other plant material or combinations. For primary health care, 80% of the total population of this world use herbal drugs (Atmakuri and Dathi 2010). Herbal drugs can be formulated by different techniques such as extraction, fractionation, and purication; and the structure of the marker compounds can be determined with the use of whole plant or specic plant parts (Cott 1995). Natural drugs do hold some merits over traditional medicines such as lower risk of side effects, widespread availability, low cost, and efcacy for lifestyle diseases for prolonged periods of time (Kumar and Rai 2012). Evidences on current drug therapies tell us that they simply suppress the symptoms and ignore the underlying
19.1 Introduction .................................................................................................. 523 19.2 Novel Carriers for Herbal Drugs .................................................................. 525
19.2.1 Phytosomes ....................................................................................... 525 19.2.1.1 Phytosome Technology ...................................................... 527 19.2.1.2 Preparation of Phytosomes ................................................ 527 19.2.1.3 Advantages of Phytosomes ................................................ 528 19.2.1.4 Properties of Phytosomes .................................................. 528
19.2.2 Ethosomes ......................................................................................... 529 19.2.3 Transfersomes ................................................................................... 529 19.2.4 Liposomes ......................................................................................... 530 19.2.5 Nanoparticles .................................................................................... 531 19.2.6 Emulsion-Based Systems .................................................................. 532
19.3 Targeting Approaches ................................................................................... 534 19.4 Clinical Trials of Herbal Medicines ............................................................. 536 19.5 Future Perspectives ....................................................................................... 537 References .............................................................................................................. 537
disease processes. In contrast, many natural products appear to address the cause of many diseases and give superior clinical outcomes (Devi et al. 2010). Nevertheless, the different limitations such as stability in acidic medium and metabolism in the liver decrease the drug levels below therapeutic concentrations in the blood and show less therapeutic effects (Goyal et al. 2011). The alkaloids, avonoids, tannins, and glycosides are polar and absorbed in very little amount due to their relatively large molecular size. This limits herbal drugs in crossing biological membranes, thereby reducing their absorption via the passive diffusion mechanism. Consequently, the bioavailability and therapeutic index of plant actives decrease (Giriraj 2011).
