Realgar/Indigo naturalis

Realgar/Indigo naturalis formula, also called Compound Huangdai, is an orally administered medication used to treat acute promyelocytic leukemia, combining four traditional Chinese medicine ingredients: the arsenic compound realgar, indigo naturalis, salvia root, and pseudostellaria root. It descends from an older traditional Chinese medicine combination of indigo and realgar called Qinghuang san, and the modern formulation was developed in the 1980s by Huang Shilin at the Shenyang Theatre Military Hospital, patented in 2004, and approved for medical use in China in 2009. Its arsenic component degrades the PML-RARalpha protein responsible for the leukemia, working alongside all-trans-retinoic acid with effectiveness similar to arsenic trioxide, and it appears on the World Health Organization's List of Essential Medicines even though it remains unapproved in the United States and Europe.