**1. Classification of drugs**

Drugs are classified into "over‐the‐counter (OTC) drugs" that are sold in drug stores and "medicinal (or ethical) drugs" that are prescribed by doctors [1] (**Figure 1**). "Herbal drug materials" and "Kampo (Japanese Traditional Medicines)" belong to OTC drugs, whereas new drugs and generics belong to the medicinal drugs. In contrast to Western medicines that recognize the drug as single compounds, Kampo medicines are a mixture of more than two components of herbal extracts. Pharmacopeia 17th edition accommodates a total of 323 herbal medicines (33 Kampo medicine + 290 herbal drug materials/formulations). Licorice is a crude drug prescribed in various herbal formulas in traditional Japanese and Chinese medicines and also used worldwide as a food natural sweetener. The origin

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**Figure 1.** Classification of drugs.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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of licorice was the root or stolon of Glycyrrhiza uralensis or G. glabra (Legminosae) [1]. Licorice con‐ tains three orders higher amounts of glycyrrhizin, as compared with other components [2].
