[Novel formulations of a liver protection drug glycyrrhizin].

In Japan, glycyrrhizin injections have been used as a therapeutic drug for allergy inflammation since 1948 and for chronic hepatitis since 1979. A 20 ml injection of glycyrrhizin contains 53 mg of monoammonium glycyrrhizinate (40 mg as glycyrrhizin acid), 400 mg of glycine, and 20 mg of L-cysteine. Patients receiving glycyrrhizin injections two or three times per week are forced to accept a decline in quality of life. Because administering glycyrrhizin by injection has some disadvantages, many researchers have systematically searched for novel glycyrrhizin formulations that can be administered through oral, rectal, intranasal, and subcutaneous routes. There are two problems, however, in developing new formulations: (1) glycyrrhizin has low membrane permeability and is thus poorly absorbed, and (2) highly concentrated glycyrrhizin readily forms gels in aqueous solutions. Here, we describe the utility of glycyrrhizin formulations prepared in safe solubility agents and absorption-enhancing agents, as assessed in animal experiments. We also discuss pharmaceutical issues in developing various glycyrrhizin formulations. In the near future, convenient pharmaceutical preparations of glycyrrhizin will be developed for chronic hepatitis patients who require glycyrrhizin therapy.