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Old 09-13-2013
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Arrow Nitroprusside Cyanide Toxicity

So, nitroprusside can only be administered no more than 24-36H why? cause cyanide toxicity, how does it happen?
well nitroprusside breakdown provides NO (nitro-) and cyanide (-prusside).
cyanide binds to the cytochrome oxidase in ETC (complex IV) so if toxicity like this takes place
FIRST: add nitrates which would promote formation of MetHB which as we know has high affinity for cyanide, so as soon as cyanide sees it will now hop onto it forming CYANOMetHB
SECOND: add thiosulfate which is a sulfur donor (you need the SULFUR to make it a less harmful molecule) which via RHODANASE will breakdown CyanoMetHb into *Thiocyanate - excreted by kidney*
* **MetHB - which here we use methylene blue to transform it into oxyhemoglobin

i needed to write it down so i can reinforce it, i putted here cause i guess it would help anybody and would take less time than me to finally learn it pretty well
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Old 09-13-2013
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Also WORTH mentioning,
Nitroglycerin chronic use has clinical importance due to the fact that before becoming Nitric Oxide per se it NEEDS Cysteine, lets remember that cysteine is important for replenishing Glutathione, therefore decreased cysteine = decreased glutathione
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Old 09-13-2013
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Yep, "nitrosithiol" is the intermediate for the nitrates which eventually yields nitric oxide (thiol = -SH) hence the cysteine - derived from glutathione. Chronic use may lead to acute tolerance to the action of nitrates also known as "Tachyphylaxis".

I also read another interesting story called "Monday Disease" - Workers in nitrate industries suffer from chronic exposure to nitrates but develop tolerance so develop no symptoms during the week. But during the weekend break the tolerance is lost (perhaps the glutathione reserves are regenerated) so they develop symptoms of nitrate toxicity (headaches etc.) while returning to work on Mondays due to re-exposure.

Ha, funny thing. Guess I got that from First Aid, not too sure...
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