Prophylactic activity in rodents of trypanocides complexed with dextran.

The prophylactic activity of prepared complexes of each of several trypanocidal drugs with dextran sulphate (M.W. 5 X 10(5)) was determined in rodents at the same time as that of the corresponding uncomplexed drug, and also the suramin complex in some cases. All the dextran complexes tested showed some degree of enhanced prophylaxis over the uncomplexed drug but in most cases a significant extension of prophylaxis was demonstrated only at dose levels well in excess of those used in the field. The dextran complex of isometamidium, however, showed very considerable enhancement effects over a range of dose levels. An amount of this complex containing an equivalent of the therapeutic dose of uncomplexed drug extended the period of effective prophylaxis by several months in both rats and mice. The suramin complex of isometamidium, on the other hand, was almost invariably less effective than the uncomplexed drug.