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Heavy Metals Flashcards

1
Q

The toxicity profiles of metals differ, but most of their effects appear
to result from interaction with ___________ and ___________

A
  • sulfhydryl groups of enzymes
  • regulatory proteins.
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2
Q

are organic compounds with 2 or more electronegative groups that form stable bonds with
cationic metal atoms.

A

chelators

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3
Q

These stable complexes lack the toxicity of the free metals and often are excreted readily

A

chelators

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4
Q

which function as chemical antagonists, are used as antidotes
in the treatment of heavy metal poisoning

A

Chelators

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5
Q

Heavy metals:

A
  • lead
  • arsenic
  • mercury
  • iron
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6
Q

Chelators:

A
  • Dimercaprol
  • succimer
  • penicillamine
  • Deferoxamine, deferasirox
  • EDTA
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7
Q

Lead

Lead serves no useful purpose in the body and can damage the:

A
  • hematopoietic tissues
  • liver
  • nervous system
  • kidneys
  • gastrointestinal tract
  • reproductive system
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8
Q

Lead

Lead is a major
environmental hazard because it is present in the _______ and _______
throughout the world.

A

air and water

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9
Q

Lead

Because of the ban on lead over
20 years ago in _______, and because of bans on other industrial
products that previously contained lead, acute inorganic lead poisoning is no longer common in the United States.

Acute lead poisoning

A

gasoline

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10
Q

Lead

It can occur rarely from ___________ and in children who have ingested large quantities of chips or flakes from surfaces in older houses covered with lead-containing ______.

Acute lead poisoning

A
  • industrial exposures (usually via the inhalation of dust)
  • paint
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11
Q

Lead

The primary signs of this syndrome are ______________, including, particularly in children, acute encephalopathy.

Acute lead poisoning

A

acute abdominal colic and central nervous system (CNS) changes

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11
Q

Lead

The mortality rate is high in those with ____________, and prompt ___________ is mandatory.

Acute lead poisoning

A
  • lead encephalopathy
  • chelation therapy
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12
Q

Lead

Chronic inorganic lead poisoning (plumbism) is much more _______ than the acute form.

Chronic lead poisoning

A

common

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13
Q

Lead

Signs include:

Chronic lead poisoning

A
  • peripheral neuropathy (wrist-drop is characteristic)
  • anorexia
  • anemia
  • tremor
  • weight loss
  • gastrointestinal symptoms.
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14
Q

Lead

Treatment involves removal from the source of exposure, and chelation therapy, usually with ____________ in outpatients and with _____________ in more severe cases

Chronic lead poisoning

A
  • oral succimer
  • parenteral agents (eg, EDTA with or without dimercaprol)
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14
Q

Lead

Chronic lead poisoning in children presents as:

Chronic lead poisoning

A
  • growth retardation
  • neurocognitive deficits
  • developmental delay
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15
Q

Leadv

is generally used in such children.

Chronic lead poisoning

A

Succimer

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16
Q

Lead

Similarly, studies suggest that lead may accentuate an age-related
decline in ___________ in older adults.

Chronic lead poisoning

A

cognitive function

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17
Q

Lead

In workers exposed to lead, ____________ is contraindicated because some evidence suggests that lead absorption may be enhanced by the presence of chelators

Chronic lead poisoning

A

prophylaxis with oral chelating agents

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18
Q

Lead

In contrast, high dietary
_________ is indicated because it impedes lead absorption.

Chronic lead poisoning

A

calcium

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19
Q

Lead

Now rare, poisoning by organic
lead was usually due to _________________ or ___________contained in ________ gasoline additives, which are no longer
used.

Organic lead poisoning

A
  • tetraethyl lead or tetramethyl lead
  • “antiknock”
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20
Q

Lead

This form of lead is readily absorbed through the ________ and ___________.

Organic lead poisoning

A

skin and
lungs

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21
Q

Lead

The primary signs of intoxication include:

Organic lead poisoning

A
  • hallucinations
  • headache
  • irritability
  • convulsions
  • coma
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22
Q

Lead

Treatment consists
of __________ and __________

Organic lead poisoning

A
  • decontamination
  • seizure control
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23
Q

Arsenic

Arsenic is widely used in industrial processes and is also present in certain soils and released during the __________

A

burning of coal

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24
Q

Arsenic

Acute arsenic poisoning results in:

Acute arsenic poisoning

A
  • severe gastrointestinal discomfort
  • vomiting
  • “rice-water” stools
  • capillary damage with dehydration and shock
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25
Q

Arsenic

. A _________,_____
odor may be detected in the breath and the stools.

Acute arsenic poisoning

A

sweet, garlicky

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26
Q

Arsenic

Treatment consists of __________ to replace water and electrolytes, and _______________ with ______.

Acute arsenic poisoning

A
  • supportive therapy
  • chelation therapy with dimercaprol
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27
Q

Arsenic

Chronic arsenic intoxication causes:

Chronic arsenic poisoning

A
  • skin changes
  • hair loss
  • bone marrow depression
  • anemia
  • chronic nausea
  • gastrointestinal disturbances.
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28
Q

Arsenic

________ appears to be of value

Chronic arsenic poisoning

A

Dimercaprol therapy

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29
Q

Arsenic

Arsenic is a known
human _________.

Chronic arsenic poisoning

A

carcinogen

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30
Q

Arsenic

Arsine gas (AsH3), an occupational hazard, is
formed during the ____________ and is used in the semiconductor industry

Arsine gas

A

refinement and processing of certain metals

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31
Q

Arsenic

Arsine causes a unique form
of toxicity characterized by massive _______.

Arsine gas

A

hemolysis

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32
Q

Arsenic

_________
from erythrocyte breakdown can cause renal failure

Arsine gas

A

Pigment overload

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33
Q

Arsenic

Treatment
is _______________

Arsine gas

A

supportive

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34
Q

Arsenic

Currently available _______ have not been demonstrated to be of clinical value in arsine poisoning.

Arsine gas

A

chelating agents

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35
Q

Mercury

The main source of ______ as a toxic hazard is through the use of mercury-containing materials in dental laboratories and in the manufacture of wood preservatives, insecticides, and batteries.

A

inorganic mercury

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36
Q

Mercury

________ compounds are used as seed dressings (treatments to prevent fungal and bacterial infection of seed and
to improve the seed’s dispersion and adhesiveness) and fungicides.

A

Organic mercury

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37
Q

Mercury

Acute mercury poisoning usually occurs through _____________

Acute mercury poisoning

A

inhalation of inorganic elemental mercury

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38
Q

Mercury

It causes:

Acute mercury poisoning

A
  • chest pain
  • shortness of breath
  • nausea and vomiting
  • kidney damage
  • gastroenteritis
  • CNS damage.
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39
Q

Mercury

In addition to intensive supportive care, prompt chelation with __________ or ________ is essential

Acute mercury poisoning

A
  • oral succimer
  • intramuscular dimercaprol
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40
Q

Mercury

Acute ingestion of mercuric chloride causes a severe, life-threatening ___________ followed within hours to days by acute ___________ and _________

Acute mercury poisoning

A
  • hemorrhagic gastroenteritis
  • tubular necrosis and oliguric renal failure.
41
Q

Mercury

Chronic mercury poisoning may
occur with ____ or _________

Chronic mercury poisoning

A

inorganic or organic mercury

42
Q

Mercury

Poisoning from inhalation
of mercury vapor presents as a diffuse set of symptoms involving:

Chronic mercury poisoning

A
  • the gums and teeth
  • gastrointestinal disturbances
  • neurologic and behavioral changes (erethism)
43
Q

Mercury

Chronic mercury intoxication has
been treated with ______ and _______, but their efficacy has not
been established.

Chronic mercury poisoning

A

succimer and unithiol

44
Q

Mercury

_______ may redistribute mercury to the CNS and should not be used in chronic exposure to elemental mercury

Chronic mercury poisoning

A

Dimercaprol

45
Q

Mercury

Intoxication with organic
mercury compounds was first recognized in connection with
an epidemic of __________ in the village of Minamata, Japan, which was first noticed in the 1950s

Organic mercury poisoning

A

neurologic and psychiatric disease

46
Q

Mercury

The outbreak was a result of consumption of fish containing a high content of _______ which was produced by bacteria in seawater from mercury in the effluent of a nearby vinyl plastics manufacturing plant.

Organic mercury poisoning

A

methylmercury

47
Q

Mercury

Similar epidemics have resulted from the consumption of grain that was intended for use as seed and treated with:

Organic mercury poisoning

A

fungicidal organic mercury compounds.

48
Q

Mercury

Treatment with
______ has been tried, but the benefits are uncertain.

Organic mercury poisoning

49
Q

Iron

Acute poisoning from the ingestion of ______ tablets occurs frequently in small children

A

ferrous sulfate

50
Q

Iron

although the incidence of
poisonings dropped dramatically in the United States after iron
supplements were required to be packed in __________

A

unit-dose packaging

51
Q

Iron

The initial symptoms of iron poisoning include:

A
  • vomiting
  • gastrointestinal bleeding
  • lethargy
  • gray cyanosis.
52
Q

Iron

These can be followed by signs of:

A
  • severe gastrointestinal necrosis
  • pneumonitis
  • aundice
  • seizures
  • coma
53
Q

Iron

________ is the chelating agent of choice.

A

Deferoxamine

54
Q

Iron

Chronic excessive intake of iron can lead to ___________ or _________

A

hemosiderosis
or hemochromatosis

55
Q

CHELATORS

Chelators used clinically include:

A
  • dimercaprol (BAL)
  • succimer
  • unithiol
  • penicillamine
  • edetate (EDTA)
  • deferoxamine
  • deferasirox
56
Q

CHELATORS

Variations among these agents in their _______ for specific metals govern their clinical applications

A

affinities

57
Q

Dimercaprol

Dimercaprol (2,3 dimercaptopropanol; BAL [British antilewisite]) is a __________; that is, a chelator that forms 2 bonds with the metal ion

A

bidentate chelator

58
Q

Dimercaprol

Dimercaprol prevents the ______________ and permitting its rapid excretion.

A

metal’s binding to tissue proteins

59
Q

Dimercaprol

Dimercaprol is used in acute ___________ and _________ and, in combination with EDTA, for ____________

Clinical use

A
  • arsenic and mercury poisoning
  • lead poisoning
60
Q

Dimercaprol

It is an oily liquid that must be given ____________

Clinical use

A

parenterally

61
Q

Dimercaprol

Dimercaprol causes a high incidence of adverse effects, possibly because it is ________ and readily enters cells.

Toxicity

A

highly lipophilic

62
Q

Dimercaprol

Its toxicity includes:

Toxicity

A
  • transient hypertension
  • tachycardia
  • headache
  • nausea and vomiting
  • paresthesias,
  • fever (especially in children).
63
Q

Dimercaprol

It may cause pain and hematomas at the __________.

Toxicity

A

injection site

64
Q

Dimercaprol

Long-term use is associated with __________ and ___________

Toxicity

A
  • thrombocytopenia
  • increased prothrombin time
65
Q

Succimer

Succimer (2,3-dimercaptosuccinic acid; DMSA) is a water-soluble
_________ of dimercaprol

A

bidentate congener

66
Q

Succimer

Succimer is used for the oral treatment of _________ in children and adults

Clinical use

A

lead toxicity

67
Q

Succimer

It is as effective as ________ in reducing blood lead concentration.

Clinical use

A

parenteral EDTA

68
Q

Succimer

succimer is also effective in ___________ and ______, if given within a few hours of exposure.

Clinical use

A

arsenic and mercury poisoning

69
Q

Succimer

Although succimer appears to be less toxic than dimercaprol, the following may occur:

Toxicity

A
  • gastrointestinal distress
  • CNS effects
  • skin rash
  • elevation of liver enzymes
70
Q

Unithiol

A water-soluble derivative of dimercaprol, unithiol can be administered _______ or ________

A

orally or intravenously.

71
Q

Unithiol

Intravenous unithiol is used in the initial treatment of severe acute poisoning by _______ or _______

Clinical use

A

inorganic mercury or arsenic

72
Q

Unithiol

Oral unithiol is an alternative to succimer in the treatment of _________

Clinical use

A

lead intoxication

73
Q

Unithiol

Unithiol causes a low incidence of _________, usually mild.

Toxicity

A

dermatological reactions

74
Q

Unithiol

______ and ______ may occur with rapid intravenous infusion.

Toxicity

A

Vasodilation and hypotension

75
Q

Penicillamine

Penicillamine, a derivative of penicillin, is another _________.

A

bidentate chelator

76
Q

Penicillamine

The major uses of penicillamine are in the treatment of _____ and __________.

Clinical use

A

copper poisoning and Wilson’s disease

77
Q

Penicillamine

It is sometimes used as adjunctive therapy in _______ and _______

Clinical use

A
  • gold, arsenic, and lead intoxication
  • rheumatoid arthritis.
78
Q

Penicillamine

The agent is water-soluble, well
absorbed from the __________, and excreted __________.

Clinical use

A
  • gastrointestinal tract
  • unchanged
79
Q

Penicillamine

Adverse effects are common and may be severe. They include:

Toxicity

A
  • nephrotoxicity with proteinuria
  • pancytopenia
  • autoimmune dysfunction (lupus erythematosus and hemolytic anemia)
80
Q

Ethylenediaminetetraacetic Acid

Ethylenediaminetetraacetic acid (EDTA; edetate) is an efficient
___________

A

polydentate chelator

81
Q

Ethylenediaminetetraacetic Acid

polydentate chelator of many _______ and ________

A
  • divalent cations (including calcium)
  • trivalent cations
82
Q

Ethylenediaminetetraacetic Acid

The primary use of EDTA is in the treatment
of _________

Clinical use

A

lead poisoning

83
Q

Ethylenediaminetetraacetic Acid

Because the agent is highly polar, it is given
_________.

Clinical use

A

parenterally

84
Q

Ethylenediaminetetraacetic Acid

To prevent dangerous hypocalcemia, EDTA is given
as the____________

Clinical use

A

calcium disodium salt

85
Q

Ethylenediaminetetraacetic Acid

The most important adverse effect of the agent is ___________, including _____________.

Toxicity

A
  • nephrotoxicity
  • renal tubular necrosis
86
Q

Ethylenediaminetetraacetic Acid

This risk can be reduced by adequate hydration and restricting treatment with
EDTA to _________.

Toxicity

A

5 days or less

87
Q

Ethylenediaminetetraacetic Acid

__________ can occur
at high doses.

Toxicity

A

Electrocardiographic changes

88
Q

Deferoxamine and Deferasirox

Deferoxamine is a _________

A

polydentate bacterial product

89
Q

Deferoxamine and Deferasirox

extremely high and selective affinity for _____ and a much lower affinity for _______

A
  • iron
  • aluminum
90
Q

Deferoxamine and Deferasirox

Fortunately, the drug competes poorly for _______ in hemoglobin and cytochromes

91
Q

Deferoxamine and Deferasirox

_______ is a newer tridentate
chelator with selectively high affinity for iron.

A

Deferasirox

92
Q

Deferoxamine and Deferasirox

Deferoxamine is used parenterally in the treatment of ___________ and _____________

Clinical use

A
  • acute iron intoxication
  • iron overload
93
Q

Deferoxamine and Deferasirox

acute iron intoxication and iron overload is caused by blood transfusions in patients with diseases such as __________ or ________

Clinical use

A
  • thalassemia
  • myelodysplastic syndrome
94
Q

Deferoxamine and Deferasirox

___________ is an oral drug approved for treatment of iron overload.

Clinical use

A

Deferasirox

95
Q

Deferoxamine and Deferasirox

_________ may
occur.

Toxicity

A

Skin reactions (blushing, erythema, urticaria)

96
Q

Deferoxamine and Deferasirox

With long-term use, itt can cause:

Toxicity

A
  • neurotoxicity (eg, retinal degeneration)
  • hepatic
  • renal dysfunction
  • severe coagulopathies
97
Q

Deferoxamine and Deferasirox

Rapid intravenous administration of deferoxamine can
cause ___________ and ________

Toxicity

A
  • histamine release
  • hypotensive shock
98
Q

Prussian Blue

Prussian blue is a hydrated ____________ in which Fe2+ and Fe3+ atoms are coordinated with _______ in a cubic lattice structure.

A
  • crystalline compound
  • cyanide groups
99
Q

Prussian Blue

Prussian blue is approved for the treatment of contamination with _____________ and intoxication with _________

A
  • radioactive cesium (137Cs)
  • thallium salts.
100
Q

High-Yield Terms to Learn

A molecule with 2 or more electronegative groups that can form stable coordinate complexes with multivalent
cationic metal atoms

A

Chelating
agent

101
Q

High-Yield Terms to Learn

Syndrome resulting from mercury poisoning characterized by insomnia, memory loss, excitability, and delirium

102
Q

High-Yield Terms to Learn

A range of toxic syndromes due to chronic lead poisoning that may vary as a function of blood or tissue levels and patient age

tcol (10 decks)

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