Editing Amyl nitrite (section)

== Toxicity ==
Although there are case reports of life-threatening toxicity involving unusually large amounts,<ref name="Modarai_2002">{{cite journal | vauthors = Modarai B, Kapadia YK, Kerins M, Terris J | title = Methylene blue: a treatment for severe methaemoglobinaemia secondary to misuse of amyl nitrite | journal = Emergency Medicine Journal | volume = 19 | issue = 3 | pages = 270–271 | date = May 2002 | pmid = 11971852 | pmc = 1725875 | doi = 10.1136/emj.19.3.270 }}</ref> typical inhaled doses of amyl nitrite are considered relatively safe.<ref>{{cite journal | vauthors = Nutt D, King LA, Saulsbury W, Blakemore C | title = Development of a rational scale to assess the harm of drugs of potential misuse | journal = Lancet | volume = 369 | issue = 9566 | pages = 1047–1053 | date = March 2007 | pmid = 17382831 | doi = 10.1016/S0140-6736(07)60464-4 | s2cid = 5903121 }}</ref><ref>{{cite web | vauthors = O'Malley MF, O'Malley R |date=May 2020|title=Volatile Nitrites|url=https://www.msdmanuals.com/en-gb/professional/special-subjects/recreational-drugs-and-intoxicants/volatile-nitrites | work = MSD Manual | publisher = 2023 Merck & Co., Inc. }}</ref> However, liquid amyl nitrite is highly toxic when ingested because of the dangerously high concentration it causes in the blood.<ref name="Toxbase">{{cite web |date=December 2018 |title=Amyl Nitrite |url= https://www.toxbase.org |access-date= September 29, 2020 |website=Toxbase |publisher=UK National Poisons Information Service}}</ref> Regardless of the form or route of administration, acute toxicity principally results when the nitrite oxidizes a significant proportion of hemoglobin in the blood without oxygen, forming methemoglobin, which cannot carry oxygen. Severe poisoning cases will progress to [[methemoglobinemia]], characterized by a blue-brown discoloration under the skin which could be mistaken for cyanosis.<ref name="Modarai_2002" /><ref name="Toxbase" /> Treatment with oxygen and intravenous methylene blue frustrates visual confirmation further as methylene blue itself is, as its name suggests, a blue dye; the patient's changes in different shades of blue notwithstanding, it is an effective antidote by way of catalyzing the production of the enzyme responsible for reducing the methemoglobin in the blood back to hemoglobin.

The discoloration does mean that regular near-infrared–based pulse oximetry becomes useless. More fundamentally, blood gas analysis on the whole has limited effectiveness, as the increased methemoglobin level increases the oxygen binding affinity of regular hemoglobin.<ref name="Modarai_2002" /> Therefore, the measurement of actual ratios and levels of methemoglobin and hemoglobin must accompany any blood gas partial pressure sample in these cases.