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.
2
Q
are organic compounds with 2 or more electronegative groups that form stable bonds with
cationic metal atoms.
A
chelators
3
Q
These stable complexes lack the toxicity of the free metals and often are excreted readily
A
chelators
4
Q
which function as chemical antagonists, are used as antidotes
in the treatment of heavy metal poisoning
A
Chelators
5
Q
Heavy metals:
A
- lead
- arsenic
- mercury
- iron
6
Q
Chelators:
A
- Dimercaprol
- succimer
- penicillamine
- Deferoxamine, deferasirox
- EDTA
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
8
Q
Lead
Lead is a major
environmental hazard because it is present in the _______ and _______
throughout the world.
A
air and water
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
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
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
11
Q
Lead
The mortality rate is high in those with ____________, and prompt ___________ is mandatory.
Acute lead poisoning
A
- lead encephalopathy
- chelation therapy
12
Q
Lead
Chronic inorganic lead poisoning (plumbism) is much more _______ than the acute form.
Chronic lead poisoning
A
common
13
Q
Lead
Signs include:
Chronic lead poisoning
A
- peripheral neuropathy (wrist-drop is characteristic)
- anorexia
- anemia
- tremor
- weight loss
- gastrointestinal symptoms.
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)
14
Q
Lead
Chronic lead poisoning in children presents as:
Chronic lead poisoning
A
- growth retardation
- neurocognitive deficits
- developmental delay
15
Q
Leadv
is generally used in such children.
Chronic lead poisoning
A
Succimer
16
Q
Lead
Similarly, studies suggest that lead may accentuate an age-related
decline in ___________ in older adults.
Chronic lead poisoning
A
cognitive function
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
18
Q
Lead
In contrast, high dietary
_________ is indicated because it impedes lead absorption.
Chronic lead poisoning
A
calcium
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”
20
Q
Lead
This form of lead is readily absorbed through the ________ and ___________.
Organic lead poisoning
A
skin and
lungs
21
Q
Lead
The primary signs of intoxication include:
Organic lead poisoning
A
- hallucinations
- headache
- irritability
- convulsions
- coma
22
Q
Lead
Treatment consists
of __________ and __________
Organic lead poisoning
A
- decontamination
- seizure control
23
# Arsenic
Arsenic is widely used in industrial processes and is also present in certain soils and released during the __________
burning of coal
24
# Arsenic
Acute arsenic poisoning results in:
| Acute arsenic poisoning
- severe gastrointestinal discomfort
- vomiting
- “rice-water” stools
- capillary damage with dehydration and shock
25
# Arsenic
. A _________,_____
odor may be detected in the breath and the stools.
| Acute arsenic poisoning
sweet, garlicky
26
# Arsenic
Treatment consists of __________ to replace water and electrolytes, and _______________ with ______.
| Acute arsenic poisoning
- supportive therapy
- chelation therapy with dimercaprol
27
# Arsenic
Chronic arsenic intoxication causes:
| Chronic arsenic poisoning
- skin changes
- hair loss
- bone marrow depression
- anemia
- chronic nausea
- gastrointestinal disturbances.
28
# Arsenic
________ appears to be of value
| Chronic arsenic poisoning
Dimercaprol therapy
29
# Arsenic
Arsenic is a known
human _________.
| Chronic arsenic poisoning
carcinogen
30
# Arsenic
Arsine gas (AsH3), an occupational hazard, is
formed during the ____________ and is used in the semiconductor industry
| Arsine gas
refinement and processing of certain metals
31
# Arsenic
Arsine causes a unique form
of toxicity characterized by massive _______.
| Arsine gas
hemolysis
32
# Arsenic
_________
from erythrocyte breakdown can cause renal failure
| Arsine gas
Pigment overload
33
# Arsenic
Treatment
is _______________
| Arsine gas
supportive
34
# Arsenic
Currently available _______ have not been demonstrated to be of clinical value in arsine poisoning.
| Arsine gas
chelating agents
35
# 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.
inorganic mercury
36
# 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.
Organic mercury
37
# Mercury
Acute mercury poisoning usually occurs through _____________
| Acute mercury poisoning
inhalation of inorganic elemental mercury
38
# Mercury
It causes:
| Acute mercury poisoning
- chest pain
- shortness of breath
- nausea and vomiting
- kidney damage
- gastroenteritis
- CNS damage.
39
# Mercury
In addition to intensive supportive care, prompt chelation with __________ or ________ is essential
| Acute mercury poisoning
- oral succimer
- intramuscular dimercaprol
40
# Mercury
Acute ingestion of mercuric chloride causes a severe, life-threatening ___________ followed within hours to days by acute ___________ and _________
| Acute mercury poisoning
- hemorrhagic gastroenteritis
- tubular necrosis and oliguric renal failure.
41
# Mercury
Chronic mercury poisoning may
occur with ____ or _________
| Chronic mercury poisoning
inorganic or organic mercury
42
# Mercury
Poisoning from inhalation
of mercury vapor presents as a diffuse set of symptoms involving:
| Chronic mercury poisoning
- the gums and teeth
- gastrointestinal disturbances
- neurologic and behavioral changes (erethism)
43
# Mercury
Chronic mercury intoxication has
been treated with ______ and _______, but their efficacy has not
been established.
| Chronic mercury poisoning
succimer and unithiol
44
# Mercury
_______ may redistribute mercury to the CNS and should not be used in chronic exposure to elemental mercury
| Chronic mercury poisoning
Dimercaprol
45
# 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
neurologic and psychiatric disease
46
# 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
methylmercury
47
# Mercury
Similar epidemics have resulted from the consumption of grain that was intended for use as seed and treated with:
| Organic mercury poisoning
fungicidal organic mercury compounds.
48
# Mercury
Treatment with
______ has been tried, but the benefits are uncertain.
| Organic mercury poisoning
chelators
49
# Iron
Acute poisoning from the ingestion of ______ tablets occurs frequently in small children
ferrous sulfate
50
# Iron
although the incidence of
poisonings dropped dramatically in the United States after iron
supplements were required to be packed in __________
unit-dose packaging
51
# Iron
The initial symptoms of iron poisoning include:
- vomiting
- gastrointestinal bleeding
- lethargy
- gray cyanosis.
52
# Iron
These can be followed by signs of:
- severe gastrointestinal necrosis
- pneumonitis
- aundice
- seizures
- coma
53
# Iron
________ is the chelating agent of choice.
Deferoxamine
54
# Iron
Chronic excessive intake of iron can lead to ___________ or _________
hemosiderosis
or hemochromatosis
55
# CHELATORS
Chelators used clinically include:
- dimercaprol (BAL)
- succimer
- unithiol
- penicillamine
- edetate (EDTA)
- deferoxamine
- deferasirox
56
# CHELATORS
Variations among these agents in their _______ for specific metals govern their clinical applications
affinities
57
# Dimercaprol
Dimercaprol (2,3 dimercaptopropanol; BAL [British antilewisite]) is a __________; that is, a chelator that forms 2 bonds with the metal ion
bidentate chelator
58
# Dimercaprol
Dimercaprol prevents the ______________ and permitting its rapid excretion.
metal’s binding to tissue proteins
59
# Dimercaprol
Dimercaprol is used in acute ___________ and _________ and, in combination with EDTA, for ____________
| Clinical use
- arsenic and mercury poisoning
- lead poisoning
60
# Dimercaprol
It is an oily liquid that must be given ____________
| Clinical use
parenterally
61
# Dimercaprol
Dimercaprol causes a high incidence of adverse effects, possibly because it is ________ and readily enters cells.
| Toxicity
highly lipophilic
62
# Dimercaprol
Its toxicity includes:
| Toxicity
- transient hypertension
- tachycardia
- headache
- nausea and vomiting
- paresthesias,
- fever (especially in children).
63
# Dimercaprol
It may cause pain and hematomas at the __________.
| Toxicity
injection site
64
# Dimercaprol
Long-term use is associated with __________ and ___________
| Toxicity
- thrombocytopenia
- increased prothrombin time
65
# Succimer
Succimer (2,3-dimercaptosuccinic acid; DMSA) is a water-soluble
_________ of dimercaprol
bidentate congener
66
# Succimer
Succimer is used for the oral treatment of _________ in children and adults
| Clinical use
lead toxicity
67
# Succimer
It is as effective as ________ in reducing blood lead concentration.
| Clinical use
parenteral EDTA
68
# Succimer
succimer is also effective in ___________ and ______, if given within a few hours of exposure.
| Clinical use
arsenic and mercury poisoning
69
# Succimer
Although succimer appears to be less toxic than dimercaprol, the following may occur:
| Toxicity
- gastrointestinal distress
- CNS effects
- skin rash
- elevation of liver enzymes
70
# Unithiol
A water-soluble derivative of dimercaprol, unithiol can be administered _______ or ________
orally or intravenously.
71
# Unithiol
Intravenous unithiol is used in the initial treatment of severe acute poisoning by _______ or _______
| Clinical use
inorganic mercury or arsenic
72
# Unithiol
Oral unithiol is an alternative to succimer in the treatment of _________
| Clinical use
lead intoxication
73
# Unithiol
Unithiol causes a low incidence of _________, usually mild.
| Toxicity
dermatological reactions
74
# Unithiol
______ and ______ may occur with rapid intravenous infusion.
| Toxicity
Vasodilation and hypotension
75
# Penicillamine
Penicillamine, a derivative of penicillin, is another _________.
bidentate chelator
76
# Penicillamine
The major uses of penicillamine are in the treatment of _____ and __________.
| Clinical use
copper poisoning and Wilson’s disease
77
# Penicillamine
It is sometimes used as adjunctive therapy in _______ and _______
| Clinical use
- gold, arsenic, and lead intoxication
- rheumatoid arthritis.
78
# Penicillamine
The agent is water-soluble, well
absorbed from the __________, and excreted __________.
| Clinical use
- gastrointestinal tract
- unchanged
79
# Penicillamine
Adverse effects are common and may be severe. They include:
| Toxicity
- nephrotoxicity with proteinuria
- pancytopenia
- autoimmune dysfunction (lupus erythematosus and hemolytic anemia)
80
# Ethylenediaminetetraacetic Acid
Ethylenediaminetetraacetic acid (EDTA; edetate) is an efficient
___________
polydentate chelator
81
# Ethylenediaminetetraacetic Acid
polydentate chelator of many _______ and ________
- divalent cations (including calcium)
- trivalent cations
82
# Ethylenediaminetetraacetic Acid
The primary use of EDTA is in the treatment
of _________
| Clinical use
lead poisoning
83
# Ethylenediaminetetraacetic Acid
Because the agent is highly polar, it is given
_________.
| Clinical use
parenterally
84
# Ethylenediaminetetraacetic Acid
To prevent dangerous hypocalcemia, EDTA is given
as the____________
| Clinical use
calcium disodium salt
85
# Ethylenediaminetetraacetic Acid
The most important adverse effect of the agent is ___________, including _____________.
| Toxicity
- nephrotoxicity
- renal tubular necrosis
86
# Ethylenediaminetetraacetic Acid
This risk can be reduced by adequate hydration and restricting treatment with
EDTA to _________.
| Toxicity
5 days or less
87
# Ethylenediaminetetraacetic Acid
__________ can occur
at high doses.
| Toxicity
Electrocardiographic changes
88
# Deferoxamine and Deferasirox
Deferoxamine is a _________
polydentate bacterial product
89
# Deferoxamine and Deferasirox
extremely high and selective affinity for _____ and a much lower affinity for _______
- iron
- aluminum
90
# Deferoxamine and Deferasirox
Fortunately, the drug competes poorly for _______ in hemoglobin and cytochromes
heme iron
91
# Deferoxamine and Deferasirox
_______ is a newer tridentate
chelator with selectively high affinity for iron.
Deferasirox
92
# Deferoxamine and Deferasirox
Deferoxamine is used parenterally in the treatment of ___________ and _____________
| Clinical use
- acute iron intoxication
- iron overload
93
# Deferoxamine and Deferasirox
acute iron intoxication and iron overload is caused by blood transfusions in patients with diseases such as __________ or ________
| Clinical use
- thalassemia
- myelodysplastic syndrome
94
# Deferoxamine and Deferasirox
___________ is an oral drug approved for treatment of iron overload.
| Clinical use
Deferasirox
95
# Deferoxamine and Deferasirox
_________ may
occur.
| Toxicity
Skin reactions (blushing, erythema, urticaria)
96
# Deferoxamine and Deferasirox
With long-term use, itt can cause:
| Toxicity
- neurotoxicity (eg, retinal degeneration)
- hepatic
- renal dysfunction
- severe coagulopathies
97
# Deferoxamine and Deferasirox
Rapid intravenous administration of deferoxamine can
cause ___________ and ________
| Toxicity
- histamine release
- hypotensive shock
98
# Prussian Blue
Prussian blue is a hydrated ____________ in which Fe2+ and Fe3+ atoms are coordinated with _______ in a cubic lattice structure.
- crystalline compound
- cyanide groups
99
# Prussian Blue
Prussian blue is approved for the treatment of contamination with _____________ and intoxication with _________
- radioactive cesium (137Cs)
- thallium salts.
100
# High-Yield Terms to Learn
A molecule with 2 or more electronegative groups that can form stable coordinate complexes with multivalent
cationic metal atoms
Chelating
agent
101
# High-Yield Terms to Learn
Syndrome resulting from mercury poisoning characterized by insomnia, memory loss, excitability, and delirium
Erethism
102
# 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
Plumbism
