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9 Cards in this Set
- Front
- Back
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Cyanide (CN-) |
2 process to manufact: 1) Andrussow process uses O2 under dH = - kcal/mol 2) BMA process w/o O2 under dH = + kcal/mol -small scale manufact in lab = H+ + NaCN --> HCN + Na+ |
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Exposure |
-Natural = cyanogenic glycosides in cassava, almonds, apple seed
-industrial = fumigant, insecticide, smoke inhalation (smoking, combustion of N containing materials ex. polyacrylonitrile), pharma (ex. long term use of nitroprusside vasodilator) |
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Normal metabolism |
-80% CN --> thiocynate (SCN-) that is not toxic by rhodonase (hepatic mitochondrial enzyme) -breathe out HCN -react w/ hydroxocobalamin (precursor of VitB12) to form cyanocobalamin (Vit B12) -oxidation to formic acid and CO2 -react w/ cystine |
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Cyanide Toxicity |
-binds to transitional metals Ex. iron. Iron is found in the blood, and also in cytochromes --> cytochrome C oxidase (complex 4) of the ETC = prevents delivery of electrons for O2 = no aerobic ATP production |
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Toxidrome |
-unspecific = dizzy, weak, headache, confusion -coma -tachypnea (rapid breath) -pink of skin b/c of hyperventilation = blood vessel dilation near skn |
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Treatment |
-airway control + 100% O2 -volume support -bicarb to combat met acidosis from anaerobic resp -specific therapies: 1) amyl nitrate 2) sodium nitrite 3) sodium thiosulphate 4) hydroxocobalamin |
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Amyl nitrate |
-potent vasodilator by delivery of NO -causes oxidation of Fe2+ in Hg to Fe3+ = methemoglobin; flood with Fe3+ so CN binds to blood iron and not Fe3+ in cytochrome. (Fe3+ has higher affinity for CN- than cytochrome c oxidase). however, methemoglobin cannot release O2, so have to figure out how much Hg iron to convert w/o ******* things up (usually 50% Hg convert) |
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-Sodium nitrate -Sodium Thiosulphate -Hydroxocobalamin |
-weak oxidizing agent = induce methemoglobinemia -substrate for rhodanase = keep converting -to make Vit B12 |
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Principles of Analysis |
-colorimetric = CN- liberated from blood by add of strong acid and HCN is trapped in basic solution as CN- again --> convert to CNCl by rxn w/ chloramine-T = color is formed when add pyridine-barbituric acid rgnt --> read at 578 nm -microdiffusion -potentiometric -GC -LC -GCMS -SCN- determination = for patients on sodium nitroprusside, need to monitor -> testing only after 7-14 days b/c SCN- won't be present (i.e. CN won't be converted to) in appreciable amount. Can't be be used in acute cyanide toxicity! |
