1.Two new trivalent organic arsenicals with favorable chemotherapeutic indices as compared with tryparsamide were given trial against African sleeping sickness caused by Trypanosoma gambiense.
2.One of these trivalent compounds, Melarsen oxide, is not only active in the blood and lymph node stage but also has a pronounced effect in the cerebral stage.
3.These effects followed both oral and intravenous administration.
4.No toxic reactions to the doses of Melarsen oxide were noted in any of our patients.
5.In the early stage, the dosage of Melarsen oxide was adequate to produce uniformly satisfactory results. The same dosage given to patients with cerebral involvement always produced amelioration, but this improvement was sometimes only temporary. It seems quite probable that in this initial trial the single dosage and rhythm of injection adopted was not the optimal therapy for advanced patients.
6.The results thus far obtained with Melarsen oxide appear sufficiently encouraging to warrant further investigation in order to determine this optimum and then to compare the compound in regard to cure and relapse rates, toxicity and also activity in Trypanosoma rhodesiense infections with drugs now in current use.
7.The second drug employed, 70A, appears to be effective in the early stage of gambian trypanosomiasis, but neither prevented nor ameliorated cerebral involvement despite intravenous doses of 380 to 400 mg. administered during 20 to 30 days.