CHEMOTHERAPY 120 



A theory <jf drug action different from Elu'lich\s 

 receptor theory led to the discovery of a group of drugs 

 which have proved of great value in several trypanosome 

 diseases. The drug synthalin, decamethylene diguanidine, 

 NH XH 



C— NH.(CH2)io. NH— c , had been used in diabetes 



NH2 NH2 



because it had a similar effect to insulin in lowering the 

 blood sugar content. Jansco thought that it might be 

 effective in trypanosomiasis by lowering the blood sugar to 

 such an extent as to starve out the trypanosomes, in the 

 same way as he had succeeded in preventing trypanosome 

 infections in mice by inhibiting their carbohydrate 

 metabolism with iodoacetic acid. It so happened that 

 the drug was active against. trypanosomes, although not 

 for the reasons which led to its trial. Investigation of 

 drugs of similar constitution brought to light stilbamidine, 

 diamidino-stilbene, 



NH NH 



C — < >CH = CH 



I ^ ^ 



NH2 



which is the most effective drug yet known for the 



treatment of kala-azar. and pentamidine, 



NH NH 



C 



NH2 



NH3 



for babesia in cattle. Propamidine, 

 NH 



' ^ -0— (CHa),— 0— 



NH2 



has also proved of value in trjrpansomiasis, kala-azar and 



babesiasis. 



To Summarise : — Trypanosomes are susceptible to the 



