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On the Action of Antimony Comjminds in Tryjjcinosomiasis in 

 Rats : being a Reimrt to a Snh- Committee of the Tropical 

 Diseases Committee of the Royal Society. 

 By John D. Thomson, M.B., CM., and Arthur R. Cusiiny, M.D., F.R.S. 



(Received November 23, 1909,— Read January 20, 1910.) 



The near chemical and pharmacological relation of arsenic and antimony 

 suggested naturally the use of the latter in a disease in which the former 

 liad proved of value ; but the irritant action of the ordinary antimony salts 

 seemed to preclude their use by hypodermic injection. After repeated 

 attempts to form organic compounds of antimony analogous to atoxyl, one 

 of us (C.) submitted to Plimmer and Thomson, for experimental trial, a 

 compound of glycine and antimony, and their results with it showed that 

 antimony possesses trypanocidal properties. This first antimony compound 

 proved difficult to make and unstable, however, and these observers 

 substituted for it tartar emetic ; the results were satisfactory, and the 

 following investigation was undertaken with the object of determining the limits 

 of usefulness of other antimony compounds in these diseases. The experiments 

 were made on rats infected with a strain of Nagana {T. hnicei) obtained by 

 the kindness of Sir J. McFadyean. This strain was fatal to rats within 

 six days after inoculation, or within three days after trypanosomes appeared 

 in the blood. The inoculation and treatment were carried out at the Lister 

 Institute of Preventive Medicine. 



In the use of the heavy metals it is generally recognised that the more 

 readily dissociated compounds are liable to cause more local irritation than 

 others, and where the local action is to be avoided, attempts are made to 

 use compounds which are less immediately dissociated and pass into the 

 general tissues in their original form, there to free the metallic ion compound 

 which is necessary for the desired effect. 



An example of this is offered in the substitution of atoxyl for the older 

 arsenic preparations in the treatment of trypanosomiasis, for there is no 

 question that the atoxyl owes its activity to the simpler compounds formed 

 from it in the tissues. It is possible that, in addition to avoiding local 

 irritation, such compounds as atoxyl may penetrate into cells which are 

 not permeable by ordinary arsenic salts, and that the latter may in this 

 way be liberated in cells to which they would not otherwise have had 

 access. 



With this in mind it seemed desirable to test the action of compounds in 



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