 Antimony @-@ based drugs , such as meglumine antimoniate , are also considered the drugs of choice for treatment of leishmaniasis in domestic animals . Unfortunately , as well as having low therapeutic indices , the drugs are poor at penetrating the bone marrow , where some of the Leishmania amastigotes reside , and so cure of the disease – especially the visceral form – is very difficult . Elemental antimony as an antimony pill was once used as a medicine . It could be reused by others after ingestion and elimination . 
