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11 terms

Heavy Metals & Chelators

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Dimercaprol
Indication: ARSENIC & inorganic MERCURY (Hg) poisoning (don't use w/ methylmercury poisoning)

Toxicity: hypertension, tachycardia, N&V, fever, and pain at injection site
Deferoxamine
Indication: acute IRON (Fe) poisoning

Highly selective Fe chelator that doesn't interfere w/ iron binding to hemoglobin, myoglobin, or cytochromes

Toxicity: hypotension, flushing, abdominal discomfort, rash, and increased susceptibility to infection w/ long-term use
Deferasirox
Indication: chronic IRON (Fe) poisoning

Oral administration & excreted in bile
Edetate (EDTA)
Indication: LEAD poisoning in adults (also chelates calcium, zinc, magnesium)

Mainly chelates EXTRACELLULAR IONS (not well absorbed from gut, crosses membranes very poorly) - ON/OFF cycles to allow Pb to redistribute out of bone
Succimer
Indication: LEAD poisoning in children

Water soluble analog of dimercaprol
Unithiol
Indication: acute poisoning w/ ARSENIC & inorganic MERCURY
Arsenic (As)
Most common cause of acute heavy metal toxicity

Methylated in liver & eliminated in urine

Treatment: Dimercaprol or Unithiol
Lead (Pb)
Interferes w/ biosynthesis of heme - GI is major route of lead poisoning

Toxicity: anemia, hearing defects, encephalopathy, elevated BP

Treatment: EDTA (adults) & Succimer (children)
Mercury (Hg)
Toxicity: chronic exposure - excitability, neuropsychiatric disturbances, and gingivostomatitis

Treatment: Dimercaprol (unithiol & succimer)
Cadmium (Cd)
Respiratory tract is main site of absorption - fibrosis & emphysema, also liver & renal toxicity

Treatment: supportive therapy - NO CHELATION theraphy
Iron (Fe)
Acute poisoning almost always in children

Iron Intoxication: Phase I (gastrointestinal - 30 min to 2hrs - vomiting, hematemesis, abd. pain), Phase II (recovery - 2 to 24 hrs - apparent response to therapy), Phase III (metabolic acidosis - 12 to 48 hrs - comma & death)

Treatment: Deferoxamine