Potassium arsenite forms the basis of Fowler’s solution, which was historically used as a medicinal tonic, but due to its toxic nature its use was discontinued.

[8][9] The reaction is shown below In the eighteenth century English physician Thomas Fowler (1736–1801)[10] utilized a potassium arsenite solution called Fowler’s solution to remedy a number of conditions including anemia, rheumatism, psoriasis, eczema, dermatitis, asthma, cholera, and syphilis.

Surprisingly enough, this specific use was inspired by potassium arsenite’s role in improving digestion and producing a smoother coat in horses.

[7] The toxicity of potassium arsenite arises from arsenic’s high affinity for sulfhydryl groups.

The carcinogenicity of potassium arsenite arises from its ability to inhibit DNA repair and methylation.

This impairment of the cellular machinery can lead to cancer because the cells can no longer repair or arrest mutations and a tumor results.