In Vivo and In Vitro Characterization of Different Dimethyl Trisulfide Formulations

Cyanide is a toxic cytochrome c oxidase inhibitor that prevents the production of ATP, which consequently results in lactic acidosis, histotoxic hypoxia, and death. Dimethyl trisulfide (DMTS) is a promising sulfur donor (SD) type cyanide antidote that can react with cyanide to form the less toxic thiocyanate. These studies provide more insight into the characterization and biological effects for a newly formulated FF-DMTS compared to Poly80-DMTS. The first objective was to determine the optimal pH for rhodanese activity. This was determined by observing the SD efficiencies of DMTS and thiosulfate, without rhodanese and comparing that to their activity in the presence of rhodanese at a pH of 7.4, 8.6, and 10.5. Post-reaction, the DMTS (3.5mM) was seen to be over 40x less concentrated than its TS counterpart (150mM), yet exceeds thiosulfate SD ability, supporting the idea that DMTS is a more efficient SD. Secondly, the in vitro blood brain barrier penetrability was determined using a Parallel Artificial Membrane Permeability Assay system. It was determined that the Poly80-DMTS (Papp =11.8x10-6 cm/s) penetrated the blood brain barrier more than the FF-DMTS (Papp=7.46x10-6 cm/s), although the Poly80-DMTS (tlag=6.42 min.) had a lag time over 3x longer than FF-DMTS (tlag=2.00 min.). Thirdly, when analyzing the formation of methemoglobin by DMTS in vivo, FF-DMTS produced more methemoglobin than Poly80-DMTS. The highest examined doses of both formulations, however, produced less than 30% methemoglobin, which is the percentage that would induce methemoglobinemia and require medical assistance. Lastly, when observing the particle size distribution of the two formulations using the Zetasizer Nano, the particle size of FF-DMTS was almost 3.5x higher than that of the Poly80-DMTS. This can potentially be used to explain the slower blood brain barrier penetrability of FF-DMTS. The information obtained from these studies will be used for further characterization of DMTS as a cyanide antidote. Understanding how DMTS behaves in the body will give insight into developing an alternative cyanide therapeutic agent. The information from these studies, will contribute to the development of an intramuscular injector kit, which can potentially decrease the lives lost to cyanide intoxication.