Antimony Content and Toxicity of Urea Stibamine

Abstract

UREA STIBAMINE, introduced by Brahmachari¹ in 1922 and widely employed in the treatment of kalaazar in India and elsewhere, still remains a compound with no definitely known and agreed chemical formula. It was originally reported to be a substance composed of urea and para-aminophenylstibinic acid with the empirical formula, C₇H₁₂O₄N₃Sb. Later it was suggested that the compound was identical with ammonium-para-carbamidophenylstibinate, NH₂.CO. NH.C₆H₄.SbO(OH).ONH₄². Ghosh et al.³ and Gray et al.⁴ gave definite evidence that urea stibamine was not a single substance of definite composition and the latter group of workers showed that the 'effective active principle' was a di-substituted urea, S-diphenyl-carbamide-4 : 4 distibinic acid. The antimony content of various commercial samples was shown by Ghosh et al. to vary between 20 and 43 per cent, while Gray et al. reported a comparatively smaller range of variation in antimony content from 44.19 to 48.6 per cent. Brahmachari⁵ appeared to have accepted the results of Gray et al. in this regard, and emphasized that the divergent results obtained by different investigators were due to different brands of “so-called urea stibamine”, not conforming to his original specifications, being put on the Indian market.