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29 Cards in this Set
- Front
- Back
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What is the function of a chelating agent?
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they bind heavy metals into stable complexes. These complexes have low toxicity and are easily excreted renally and fecally
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How is lead absorbed into the body?
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a. GI- paint, pottery, moonshine
b. Inhalation- metal fumes (major route) c. Skin- tetraethyl lead in gasoline |
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What is the toxicity of Lead?
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-lead inhibits porphobilinogen synthase and ferrochelatase, preventing both porphobilinogen formation and the incorporation of iron into protoporphyrin IX, the final step in heme synthesis. This causes ineffective heme synthesis and subsequent microcytic anemia
-Binds to sulfhydryl groups of proteins |
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Lead toxicity affects in 3 folds
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1) hemoglobin to RBC problems 2) Myoglobin-muscle problems
3) cytochrome-> mitchondria problems |
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How is lead poisoning detected?
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Protoporphyrin IX increase in the urine
Urinary δ aminolevulonic acid |
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What agents are used to treat lead poisoning?
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-(EDTA) Ethylenediamine-tetraacetic acid
-( Succimer)2,3-dimercatosuccinic acid -(BAL, Dimercaprol) 2,3-dimercatopropanol -Penicillamine |
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Cadmium absorption
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a. Ingestion: pigments, polishes, antique toys
Environmental- electroplating, galvanization, plastics, batteries b. Inhalation: industrial, metal fumes, tobacco- 1 – 2 μg/pack |
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Cadmium mechanism of toxicity
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a. Inhalation: lung – local irritation and inhibition of α1-antitrypsin associated with emphysema
b. Renal: Nephrotoxicity-proximal tubular injury in kidney o proteinuria o β2-macroglobulin |
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How is Cadmium toxicity detected?
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a, History of exposure
b, Blood cadmium level >80 μg/dl |
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What chelating agents are used to treat Cadmium poisoning?
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CaNa2EDTA only!
(BAL) Cadmium complex extremely nephrotoxic and therefore is not used) |
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How is Mercury absorbed?
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a. Ingestion- inorganic salts are variably absorbed (10%) but may be converted to organic mercury (methyl and ethyl in the gut by bacteria); organic compounds are well absorbed >90%
b. Inhalation- elemental mercury completely absorbed |
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What is the toxicity mechanism of mercury?
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a. dissociation of salts precipitates proteins and destroys mucosal membranes
b. necrosis of proximal tubular epithelium c. inhibition of sulfhydryl (-SH) group containing enzymes |
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How is mercury detected in pts?
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a. history of exposure
b. blood mercury >4 μg/dl |
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What chelating agents is used against mercury poisoning?
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-(NAP) N-acetyl-penicillamine
-Penicillamine -(BAL, Dimercaprol) -(Succimer) -Alkyl-Hg: non-absorbable thiol resins can be given orally to reduce alkyl-Hg travel in gut |
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Minamata disease:
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950’s epidemic of birth defects in the Japanese fishing village of
Minamata • Seafood contaminated with methylmercury thought to be source of epidemic • Mercurials were poured into the bay by a nearby factory |
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How is Arsenic absorbed?
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What is the mechanism of toxicity of Arsenic?
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a. Membranes: protein damage of capillary endothelium increased vascular permeability leading to vasodilation and vascular collapse
b. Inhibition of sulfhydryl group containing enzymes c. Inhibition of anaerobic and oxidative phosphorylation (substitutes for inorganic phosphate in synthesis of high-energy phosphates) |
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What chelating agents are used against Arsenic?
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-NAP
-Arsine gas(AsH3) (hemolytic agent) -transfusion |
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Iron chelating agents
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Deferoxamine (IM, slow IV, Oral-under rare circumstance)
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Why is EDTA given IV?
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EDTA cannot cross the cell membrane.
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why EDTA given as Calcium disodium salt.
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Because the sodium salt of EDTA can cause severe hypocalcemia
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autosomal recessive genetic disorder in which copper accumulates in tissues; this manifests as neurological or psychiatric symptoms and liver disease
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wilson's disease (copper poisoning)
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How to treat wilson's disease
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-Penicillamine
-Trientine (triethylenetetramine) o Can be used in Wilson’s disease if patient is allergic to penicillamine o Teratogenic in long-term use |
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EDTA route of administration
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IV or IM
Best for lead poisoning |
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Dimercaprol (BAL) route of administration
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IM
Works for mercury, arsenic, lead and cadmium |
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Penicillamine route of administration
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Only commercially avaible oral chelating agent
works for wilson's disease, lead, arsenic, mercury |
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Deferoxamine route of administration
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IM, slow IV, Oral-under rare circumstance)
Works for ferrous salt intoxication |
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Succimer route of administration
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Oral
works for childhood lead intoxication with serum levels of more than 45 ug/dL |
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N-acetyl-penicillamine (NAP) route of administration
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Oral
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