Arsenical drugs Drug resistance

The fact that administration of organic sulfhydryl compounds can both reverse the toxicity of these arsenic drugs and their activity tends to support this simple idea. It seems almost incredible that the organism can develop resistance to such a nonselective protoplasmic poison as arsenic, but it does, apparently by decreased uptake. 

Second phase treatments includes Melarsoprol and Eflornithine, discovered in 1949 and 1990, are available to treat the advanced stage of sleeping sickness, no matter which parasite is the cause. It is the last arsenical derivative in existence with drug-resistance in 30% padents of central Africa. 

Arsenic trioxide. Arsenic is a heavy metal that can exert toxic, poisonous effects. Therapeutic dosages of arsenic trioxide (Trisenox), however, may limit the growth of certain leukemias such as acute promyelo-cytic leukemia.11 However, because of its potential toxicity, arsenic trioxide is not usually an initial treatment, but is reserved for patients who relapse or who are resistant to other treatments. Although the exact mechanism of action is unclear, this drug apparently induces several cytotoxic effects by directly damaging DNA and proteins that regulate DNA synthesis and replication. 

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