The Prophylaxis of Experimental Trypanosomiasis by the Oral Administration of Arsenical Compounds and Germanin

John A. Kolmer Research Institute of Cutaneous Medicine of Philadelphia

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Anna M. Rule Research Institute of Cutaneous Medicine of Philadelphia

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In general terms it may be stated that of the compounds included in this study, atoxyl proved most effective in the prophylaxis of Tr. equiperdum infections of rats by oral administration. Indeed it would appear that this compound is almost as trypanocidal by oral as by intravenous administration, since the minimal single curative dose by the latter route is as high as 0.060 gram per kilogram when given twenty-four hours after intraperitoneal infection.

When given orally to white rats once a day for five to ten days immediately after intraperitoneal infection or within twenty-four hours thereof, the smallest effective doses per kilogram of weight were somewhat as follows:

Stovarsol 0.030–0.040
Treparsol 0.030–0.040
Atoxyl 0.020–0.030
Tryparsamide 0.050 (ineffective)
Bayer “205” 0.020 (ineffective)
Neoarsphenamin 0.050

It would also appear that the pentavalent arsenicals like atoxyl, stovarsol and treparsol are more effective by oral administration than a trivalent arsenical (neoarsphenamin) although the latter is more effective than the former by intravenous injection.

If Tr. gambiensi and Tr. rhodesiense are as susceptible to these pentavalent arsenicals as Tr. equiperdum, it is likely that smaller amounts per kilogram would protect human beings and as 0.020 gram per kilogram corresponds to about 1.2 gram for adults of about 135 pounds, the daily oral administration of 4 or 5 tablets of 0.25 gram each of atoxyl, stovarsol or treparsol may prove effective for the prophylaxis of human trypanosomiasis. This daily dose however, could not be kept up indefinitely because of the chances of producing enteritis and other toxic manifestations. Nor could the compounds be given to those with a natural intolerance for arsenical compounds. But otherwise the administration of 4 tablets a day for a week followed by an intermission of a week, etc., may be a practical means of affording protection for those temporarily exposed to trypanosome infection.

Author Notes