USMLE Cyanide poisoning from Nitroprusside

[Focused1]

Q: What is an early sign of cyanide poisoning from nitroprusside?

A: Early sign is tachyphylaxis to nitroprusside infusion


Can someone explain this ? I have no idea how this works ?

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[Jabbed]

Tachyphylaxis = rapid loss of response to a drug. As cyanide is a breakdown product of nitroprusside, the idea is that rapid metabolism of nitroprusside leads to cyanide toxicity. In a round about way, the first sign that this is occurring will be the absence of nitroprusside's normal physiologic effects.

Nitroprusside infusion > arteriolar dilation (drop in BP) > rapid conversion of nitroprusside to CN > decrease in nitroprusside levels / increase in cyanide levels > loss of arteriolar dilation (restoration of BP) / tachyphylaxis.

 

[Focused1]

Tachyphylaxis = rapid loss of response to a drug. As cyanide is a breakdown product of nitroprusside, the idea is that rapid metabolism of nitroprusside leads to cyanide toxicity. In a round about way, the first sign that this is occurring will be the absence of nitroprusside's normal physiologic effects.

Nitroprusside infusion > arteriolar dilation (drop in BP) > rapid conversion of nitroprusside to CN > decrease in nitroprusside levels / increase in cyanide levels > loss of arteriolar dilation (restoration of BP) / tachyphylaxis.

So just to get this straight...
Nitroprusside gets broken down and that is TACHYPHYLAXIS (which i knew) and since it's broken down there is cyanide production and subsequent toxicity ?
It's just that they have explained the concept in a round about manner and I couldn't really understand it because of the wording..
Thanks !