UNIT 6: HEAVY METALS AND CHELATORS Flashcards by lab rat

Elements with high atomic weights, densities and, atomic numbers

HEAVY METALS

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Enumerate:

Microessential nutrients

Iron, Cobalt, Zinc

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Enumerate:

Less Harmful Substances

Ruthenium, Indium

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Enumerate:

Toxic Substances

Cadmium, Mercury, Lead

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Enumerate:

These 5 have the greatest potential to cause harm especially in high amounts or doses

chromium
arsenic
cadmium
mercury
lead

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Examples of this heavy metal are

storage batteries, ammuniton, and ceramics

Lead

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Highly colored toys may contain what?

Lead

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This was also used in water pipes

coining the term “plumber”

Lead

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One of the oldest and most prevalent heavy metal that has been contaminating our environment

Lead

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T/F:

Lead has no useful purpose in the body

True

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T/F:

Lead does not cross the placenta

False

it crosses the placenta

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Deferoxamine/Deferasirox/Deferiprone

FDA approved oral treatment of iron overload caused by blood transfusions

Deferasirox

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Deferoxamine/Deferasirox/Deferiprone

Parenteral chelator of choice for iron poisoning

Deferoxamine

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Arsenic/Lead/Mercury/All:

Torsades de pointes

Arsenic

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Give the chelator or chelating agent:

Used to treat copper poisoning like Wilson’s disease

Penicillamine

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Give the chelator or chelating agent:

Used for chelation of lead as well as zinc and manganese

Edetate Calcium Disodium or EDTA

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increases or decreases?

For Lead, Low dietary calcium, iron deficiency and ingestion on an empty stomach _ absorption

increases absorption

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T/F:

The half-life of lead in bones is 1-2 months

False

the half-life in bones is years to decades

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Lead toxicity can be diagnosed in what samples? (4)

bile
skin
hair
nails

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Lead in children:

It can lead to lowering of _, hearing loss, and an increase of learning disabilities

intelligence quotient (IQ)

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T/F:

Lead may still affect adults’ intelligence quotient

False

It can lead to some neurocognitive effects but won’t affect IQ

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What types of anemia can lead cause?

normocytic
microcytic
hypochromic

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Most important complication of lead poisoning:

nervous system disorders particularly seizures

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What are the 2 major forms of lead intoxication?

Inorganic
Organic

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# Inorganic/Organic What type of lead is majorly eliminated through urine and feces?

Organic

# Example of this heavy metal are: wood preservatives, glass, MSMA

Arsenic

Groundwater may contain high amounts of what?

Arsenic

# Arsenic is metabolized via the liver via _ _

methylation reactions

Historically, used as a **pharmaceutical agent** but now limited in use

Arsenic

# what heavy metal causes DNA alterations

Arsenic

Distribution of arsenic is highest in what organs? (2)

liver & kidney

what heavy metal causes **pancytopenia**?

arsenic | acute arsenic poisoning ## Footnote *A condition in which there is a lower-than-normal number of red and white blood cells and platelets in the blood. *

This heavy metal may cause dark deposits at the gingival margin

lead/lead sulfide | "gingival lead lines"

What are used to chelate lead? (3)

* Intravenous EDTA (CaNa2EDTA) * dimercaprol * succimer (DMSA)

# what heavy metal? Months after an acute poisoning, transverse white striae (Aldrich-Mees lines) may be visible in the nails

Arsenic

Causes the raindrop pattern

Arsenic mixed with water

Used to treat acute **arsenic** poisoning?

* Unithiol * Dimercaprol

Mercury is also called?

quicksilver or liquid metal

Chronic poisoning from inhalation of what results in a classic triad of tremor, neuropsychiatric disturbance, and gingivostomatitis?

mercury vapor

Humans are exposed to this through fluorescent lamps, dental amalgams, and artisanal gold production

Mercury

Mercury is usually mined as:

HgS (in cinnabar ores)

What caused Minamata disease?

Mercury

3 forms of Mercury Intoxication

* Elemental * Organic * Inorganic

# elemental/inorganic/organic mercury major route is **respiratory**

Elemental

# elemental/inorganic/organic mercury causes erethism

Elemental

# elemental/inorganic/organic mercury Eliminated through the urine **only**

Inorganic

# elemental/inorganic/organic mercury eliminated through **deacylation**

Organic

An uncommon idiosyncratic reaction to subacute/chronic mercury exposure | occurs mainly in children

Acrodynia

Erethism is also called

Mad Hatter Disease

What should never be used for elemental or organic mercury intoxication?

Dimercaprol

What are used to treat mercury poisoning? (3)

* Unithiol * Dimercaprol * Succimer

The formation of the _ Complex prevents or reverses the toxic effects of heavy metals

Chelator-Heavy Metal Complex

Chelators are only effective in what form?

Free or ionized form

A chemical warfare agent containing arsenic

Lewisite

Other name for Dimercaprol: (BAL)

British Anti-Lewisite

What is used to treat lead poisoning? | increases excretion rate of lead

Succimer

Increases rate of excretion of **arsenic** and **lead** | (can also be used for inorganic mercury)

Dimercaprol

Decreases **mercury content** in kidney

Succimer

Associated with increase in **ALT, AST, mild neutropenia**

Succimer

Chelates **extracellular** metals ions much more effectively compared to intracellular metal ions

Edetate Calcium Disodium (EDTA)

# Adverse effect of this chelator: Stevens-Johnson Syndrome

Unithiol

Water-soluble analogs of dimercaprol

* Unithiol * Succimer

# Adverse effect of this chelator: Urticaria (hives) & Erythema multiforme

Unithiol | basta dermatologic, unithiol :D

White, crystalline, derivative of Penicillin

Penicillamine

Also used to treat severe **Rheumatoid Arthritis**

Penicillamine

has protective effects against mercury & arsenic

Unithiol

Penicillamine is also called D_ C_

Dimethyl Cysteine

This plus hemodialysis is useful in treatment of **aluminum toxicity**

Deferoxamine

Deferoxamine is isolated from what fungi?

*Streptomyces pilosus*

Give the 3 Iron Chelating Agents:

* Deferoxamine * Deferasirox * Deferiprone

# Deferoxamine/Deferasirox/Deferiprone Which is not given orally?

Deferoxamine | given via IM or IV

Other name for Prussian Blue

Ferric Hexacyanoferrate

Indicated for treatment of contamination with radioactive **Cesium** and intoxication with **thallium** salts

Prussian Blue

Are drugs used to prevent/reverse the toxic effects of a heavy metal on an enzyme

Chelating agents

It may offer therapeutic benefit in the treatment of acute intoxication by arsenic, lead, and mercury.

Dimercaprol

EDTA is indicated mainly for chelation of _

lead

What chelator has no FDA-approved indications?

Unithiol

the diagnosis of lead intoxication is best confirmed by measuring lead in ?

whole blood

% of Lead absorbed in children

50%

% of Lead absorbed in adults

10-15%

# True or False Lead is 99% free in plasma, 1% bound to RBCs

False | 99% bound to RBCs, 1% free in plasma

Half-life of Lead in **bones**

Years-Decades

Characteristic **mechanism of action** of Lead

Interference with action of **essential cations** (calcium, zinc, iron)

Metabolized via **methylation**

Arsenic

Metabolized via **deacylation**

Organic Mercury

Mechanism of Action is **Hepatic Dealkylation**

Organic Lead

**Dimercaprol**, as a single agent, is used to treat **acute poisoning** of which heavy metals? (2)

Arsenic Inorganic Mercury

Used to treat **severe lead poisoning** in conjunction with **EDTA**

Dimercaprol

Used to treat children with blood lead concentration of > 45mg/dL

Dimercaptosuccinic Acid (DMSA) | Succimer

**Second-line oral chelator** for iron overload due to blood transfusion in **thalassemia major**

Deferiprone

**Bidentate** iron chelator

Deferiprone

**Tridentate** iron chelator

Deferasirox

Used for **oral treatment** of iron overload due to blood transfusion in patients with **thalassemia major** and **myelodysplastic syndrome**

Deferasirox

Efficient in decreasing **hepatic iron**

Deferasirox

Efficient in decreasing **cardiac iron**

Deferiprone

# Elemental/Inorganic/Organic Mercury Causes **gingivastomatitis**

Elemental Mercury

# Elemental/Inorganic/Organic Mercury Causes **gastroenteritis**

Inorganic Mercury

# Elemental/Inorganic/Organic Mercury Alters **microtubules** and **neuronal structures**

Organic Mercury

# Elemental/Inorganic/Organic Mercury Alters **membranes** and inhibits **enzymes**

Elemental Mercury Inorganic Mercury

UNIT 6: HEAVY METALS AND CHELATORS Flashcards

(100 cards)