Antimony Oxidation States in Antileishmanial Drugs

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  • Department of Chemistry, University of Brasilia, Brasilia, Brazil

Chemical methods specific for the determination of the levels of trivalent antimony (Sb+3) and pentavalent antimony (Sb+5) were used to investigate proprietary formulas used to treat leishmaniasis. Trivalent antimony was determined by differential pulse polarography, whereas Sb+5 was determined by iodine titration. Proprietary formulas based on N-meglumine antimoniate (Glucantime) were analyzed in detail. The results showed Sb+3 in all ampules of Glucantime. In formulations said to contain either 85 or 100 mg of Sb+5/ml, we found both forms of antimony. The amount of Sb+3 ranged from 10.5 to 15.8% (10.06–18.96 mg of Sb/ml). These findings raise issues on product stability and standardization and may help to clarify resistance to antimonial drugs and the reducing effect of tissue on Sb+5.

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