Medical use of arsenic trioxide

Medical use of arsenic trioxide refers to the use of arsenic trioxide (Latin: Arsenum trioxydatum,^[1] also known as "arsenic") as an chemotherapeutic agent in the treatment of acute promyelocytic leukemia. Arsenic trioxide has orphan drug status^[2] and is available as the pharmaceutical preparation Trisenox. When in contact with water, it forms arsenous acid, which is believed to be the biologically active substance.

The action of this substance involves inhibiting the proliferation of cancer cells and inducing their differentiation or apoptosis, although the exact mechanism of the drug's action is not fully understood. Arsenic, due to its toxic properties, had been used for centuries as an effective and virtually undetectable^[3] poison for the senses.^[4] In the 20th century, its anticancer properties were observed, but attempts at oral administration were unsuccessful. Only intravenous administration of the substance yielded positive results, particularly in the treatment of a rare form of cancer – acute promyelocytic leukemia. This therapy is introduced after failure of treatment with retinoids and chemotherapy.^[5] The treatment is characterized by relative safety and few side effects. Research is ongoing to find other uses for the drug.