Also known as Trisenox
Arsenic trioxide is the inorganic compound with the formula As2O3. This commercially important oxide of arsenic is the main precursor to other arsenic compounds, including organoarsenic compounds. Approximately 50,000 tonnes are produced annually. Many applications are controversial given the high toxicity of arsenic compounds.Source: Wikipedia
Patients are most commonly prescribed arsenic trioxide to treat blastomycosis, rabies, west nile virus, and pick disease.