Intoxication with methemoglobinizing substances

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Aromatic amines[edit | edit source]

  • Aniline, toluidine - liquids.
  • Benzidine , 2-naphthylamine - pinkish powder substance.

Professional exposure[edit | edit source]

  • Production of dyes (textiles, paper, leather), plastics, rubber, pesticides.

Etiopathogenesis[edit | edit source]

Aniline (its metabolite phenylhydroxylamine) has the strongest methemoglobinizing effect → functional anemia occurs , the curve shifts to the left, and tissue hypoxia increases . Therapy uses alternative ways of reducing methemoglobin by the enzyme NADPH methemoglobin reductase - it needs methylene blue (a redox substance) as a cofactor.

Clinical picture[edit | edit source]

Acutelower exposureCNS excitation (so-called aniline spike);

  • Then the manifestations depend on the degree of metHbemia ,
    • 10–30% cyanosis , tachycardia , fatigue,
    • 30-50% weakness, shortness of breath, headache,
    • 50-70% impaired consciousness and death,
  • The blood taken is dark brown to black in color (striking plum-blue cyanosis).

Chronic - polyglobulia due to chronic hypoxia.

Therapy[edit | edit source]

Antidote - methylene blue .

Indication[edit | edit source]

Toluidine blue - works by the same mechanism, paradoxically, cyanosis deepens after administration (given by the color of the antidote) ascorbic acid - works weaker and slower.

Aromatic nitro compounds[edit | edit source]

  • They have the NO 2 group , e.g. nitrobenzene, TNT, trinitrophenol (picric acid),
  • Professional exposure – production of aniline, dyes, explosives,
  • Etiopathogenesis - they are well absorbed by the skin, by a similar mechanism to the previous ones, they cause methemoglobinemia. In addition, TNT causes massive necrosis and yellow atrophy of the liver with a lethal end, or cataract.

Nitroglycerin[edit | edit source]

  • Oily liquid, easily explosive,
  • Application – manufacture of explosives, pharmacology,
  • They are easily absorbed through the skin, after absorption they are hydrolyzed into inorganic compounds and cause vasodilation,
  • After 2-4 days of professional exposure, tolerance develops (thanks to compensatory sympathetic mechanisms) → angina pectoris may occur after exposure is interrupted ,
  • After high doses, methemoglobinemia, of mild degree, without Heinz bodies, may occur.
  • Acute intoxication - headaches (caused by vasodilatation of CNS vessels), "powder headache" in the occiput, restlessness, depression , sleep disorders, paleness of sweating, drop in pressure, shock,
  • High doses – methemoglobinaemia, shortness of breath, unconsciousness,
  • Professional exposure - typically the so-called "Monday sickness" - always after a weekend break, compensation sets in during the week, symptoms disappear...,
  • Chronic intoxication - angina pectoris and sudden death, paradoxically on days off from work (after interruption of exposure), pseudoneurasthenic symptoms are also described.

Therapy[edit | edit source]

  • Angina from habit - we will remove nitrates,
  • Acute hypotension is difficult to influence therapeutically - anti-shock position, IV fluids, possibly dopamine , norepinephrine .

Nitrites[edit | edit source]

Synonym: nitrites, -NO 2 ,

  • Sodium nitrite – a yellowish solid substance soluble in water,
  • It was also used as a methemoglobinizing substance in cyanide poisoning,
  • Additive for smoking meat, for cigarette papers, for fuel,
  • Lethal dose after – 4g .

Nitrates[edit | edit source]

Synonym: nitrates, -NO 3 ,

  • In order to cause metHbemia, they must be reduced to nitrites by flora in the intestine,
  • They are dangerous for infants (they have bacteria in the GIT higher - due to less acidic stomach contents),
  • As little as 10 mg/l can be dangerous for infants,
  • Others, chlorates, drugs – primaquine (antimalarial), phenacetin (analgesic).

Links[edit | edit source]

related articles[edit | edit source]

Source[edit | edit source]


References[edit | edit source]

  • PELCLOVÁ, Daniela. Nemoci z povolání a intoxikace. 2. vydání. Praha : Karolinum, 2006. 207 s. ISBN 80-246-1183-X