Well it forms part of the antidote. The nitrite esters are used due to the great rapidity of action. The rest consists of an IV dose of sodium nitrite, to further form methaemoglobin, which binds cyanide more avidly than haemoglobin does, although it cannot carry oxygen (methaemoglobin formation is the reason carbon monoxide is toxic), sodium thiosulfate should then be given intravenously, as should hydroxocobalamin (hydroxy version of vitamin B12, gets converted in-vivo to cyanocobalamin,the most common form of B23, unlike nitrites, acts within cells, rather than only within the vasculature)
The thiosulfate then rips off the cyanide from cytochrome oxidase, allowing it to be excreted as harmless thiocyanate.
Of course then the methaemoglobinaemia must then be treated with IV methylene blue.and of course, oxygen therapy should bee given immediately straight away.