Increase in Toxicity of Stilbamidine Solution on Exposure to Light

Abstract

THE increasing use of Stilbamidine (4 : 4'-diamidinostilbene di-?-hydroxyethane-sulphonate) for treatment of kala-azar in the Sudan¹ and India² makes the properties of this drug a matter of some importance. Kirk³ reported that solutions of the drug which had been made up and exposed to light for some time appeared to have increased in toxicity. Fulton and Yorke⁴ have confirmed this suggestion experimentally, and our own work, carried out independently as a result of Kirk's observations, has given similar results. Dilute solutions of Stilbamidine (0.5 per cent), exposed to sunlight, increase in toxicity four-or five-fold in about four days, after which there is no appreciable further increase. Weak solutions (0.5 per cent) change much more rapidly than do stronger, but by subjecting 10 per cent solutions to the light from a mercury arc lamp for several hours, we have been able to prepare sufficient quantities of toxic solution for isolation of the material responsible for this toxicity.