In Vitro Antileishmanial Properties of Neutron-Irradiated Meglumine Antimoniate

Pentavalent antimony, as meglumine antimoniate (Glucantime) or sodium stibogluconate (Pentostam), is the main treatment for leishmaniasis, a complex of diseases caused by the protozoan Leishmania, and an endemic and neglected threat in Brazil. Despite over half a century of clinical use, their mechanism of action, toxicity and pharmacokinetic data remain unknown. The analytical methods for determination of antimony in biological systems remain complex and have low sensitivity. Radiotracer studies have a potential in pharmaceutical development. The aim of this study was to obtain a radiotracer for antimony, with suitable physical and biological properties. Meglumine antimoniate was neutron irradiated inside the IEA-R1 nuclear reactor, producing two radioisotopes 122Sb and 124Sb, with high radionuclidic purity and good specific activity. This compound showed the same antileishmanial activity as the native compound. The use of the radiotracers, easily created by neutron irradiation, could be an interesting tool to solve important questions in antimonial pharmacology.