Development of Realgar Nanotherapeutics for Cancer Treatments

Realgar is a kind of mineral drug and has a long history of medical use in Chinese medicine. The active component of realgar is As4S4 and can be orally administrated. In past decades, several traditional Chinese prescriptions containing realgar has showed certain clinical effects in the treatment of some hematologic malignancies. However, realgar is poorly soluble in neutral or acidic aqueous solution due to its crystal structures, which not only leads to the problem of extremely low bioavailability in clinical practices but also sets up obstacles to biomedical studies to understand molecular mechanisms. Hence, there have been continuous efforts made to seek effective approaches for developing suitable processing techniques of realgar, aiming to increase the bioavailability and efficacy, and meanwhile, also to get insights into pharmaceutical mechanisms at molecular levels. This chapter briefly introduces the history of medical use of realgar in Chinese medicine prescriptions, followed by a comprehensively review of the efforts for developing realgar nanotherapeutics by using various technologies, especially a novel one-step preparation approach to fabricate nanoformulation was addressed. In the last part, therapeutic effects of realgar nanoformulations in cells and animals of acute and chronic myeloid leukemia and solid tumors are demonstrated, and molecular mechanisms are portrayed as well.