Experiments on the mode of action of stilbamidine

Tracer studies of the distribution and trypanocidal action of stilbamidine in rats

[(14)C]Stilbamidine was used to study the distribution of the drug in the organs and tissues of rats following intravenous injection. The prophylactic action of stilbamidine was shown to depend upon the unchanged drug retained in tissues, especially the liver. Only the parent drug was extracted from trypanosomes when an infection was treated during the acute phase, as shown by the use of the fluorescent properties of stilbamidine in conjunction with scanning and chromatographic techniques. The action of stilbamidine on trypanosomes is therefore a direct one. A method for the synthesis of [(14)C]stilbamidine in much improved yield is also described.

A STUDY OF GRANULES AND OTHER CHANGES IN PHASE-CONTRAST APPEARANCE PRODUCED BY CHEMOTHERAPEUTIC AGENTS IN TRYPANOSOMES

The morphological changes produced by four series of organic trypanocidal drugs have been studied by quantitative and by qualitative methods using phase-contrast and fluorescence microscopy. Basic drugs were absorbed rapidly into the region of the kinetoplast; acidic drugs did not affect this region. Faint granules, which were present in some trypanosomes before the administration of drugs, absorbed the drugs and increased in contrast relative to the cytoplasm. Hydroxystilbamidine, quinapyramine, related compounds, and possibly also suramin produced additional granules which did not contain drug. These additional granules are similar to the granules (volutin granules) which occur in trypanosome infections (not treated with drugs) when trypanosomes are about to be cleared from the blood. Homidium did not produce additional granules.