Selective Antagonism of Arsenicals and Antimonials

Abstract

WE have long been looking for an antagonist of arsenicals and antimonials to decrease selectively their toxic action, without interfering with their therapeutic effectiveness. The dimercaptans behave in the opposite way: for example, 2,3-dimereaptopropanol (BAL), in one-eighth of the dose of ‘Arsenoxide’ employed, abolishes anti-trypanosomal activity, and only multiple doses of toxic arsenic can act as antidote¹. Having observed BAL to abolish the activity of penicillin and chloromycetin in spirochaete infections without affecting antistreptococcal activity², we realized that selective antagonism against particular cells, which could be host cells, is possible. We found that ‘Penicillamine’ (dimethylcysteine, DMC) whiuh is known to detoxify bivalent heavy metals (mercury, lead)^3–5 is also a powerful antidote against arsenicals and antimonials, which does not interfere, within a wide range, with their antiparasitic effectiveness in vivo and in vitro.