Exam 3: Heavy Metal Toxicities Flashcards Preview

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Flashcards in Exam 3: Heavy Metal Toxicities Deck (54):
1

Describe the 4 ways that metals can produce toxicity in humans

1. Disrupt enzymatic and transport processes
2. Loss of energy production
3. Loss of ion regulation
4. Potential carcinogenesis

2

Arsenic naturally occurs as what compound?

- Arsenopyrite
- Most common arsenic containing material

3

What is the use for Arsenic?

- Used therapeutically to kill amoebas and parasites (in developing countries)
- Used for homicides and suicides

4

Local effect of Arsenic:

Dermatological

5

Name the systemic effects that Arsenic can have

1. Vasodilation of capillaries
2. GI effects (vomiting leads to fluid loss and CV collapse)
3. CNS effects (peripheral neuropathies, organic encephalopathy)
4. Headache
5. Coma
6. "Garlic Breath"
7. Teratogenic
8. Carcinogenic

6

How might one diagnose arsenic poisoning easily?

- Garlic breath
Able to diagnose due to smell of breath

7

Describe the mechanism behind Arsenic causing vasodilation of capillaries

Arsenic binds to contractile mechanism so cannot contract

8

The vasodilation effect of Arsenic is evident in what symptoms

- Rosy complexion
- Edema
- No wrinkles

9

What drug is used to treat Arsenic Poisoning

- Dimercaprol
**other names: BAL (British Anti-Lewisite); dithioglycerol

10

What is the mechanism of action for Dimercaprol

Sulfhydryl group combines with ions of various heavy metals to form relatively stable, nontoxic, soluble chelates which are excreted in urine

11

T or F, Antimony resembles a metal and reacts as such

- False, It resembles a metal but does not react chemically as one.
- Highly toxic

12

Antimony can be used pharmacologically how?

Used for treatment of protozoan infections

13

Explain the small doses vs large dose response when exposed to Antimony

- Small: Headache, dizziness, depression
- Large: violent and frequent vomiting, diarrhea, muscle pain; death within a few days

14

What is the antidote to Antimony?

Dimercaprol

15

Describe Argyria and the symptoms associated with it

- Definition: Silver and silver-containing compounds become absorbed into the circulatory system and deposited into body tissues
- Symptoms
○ Bluish-grayish pigmentation of skin and mucous membranes
- Permanent but not harmful

16

Argyria is often mistaken for what other toxicity?

Cyanosis

17

T or F, Argyria is permanent and can be harmful

False, Not harmful

18

Gold is used in what way pharmacologically

- Used in dentistry
- Used for treatment of rheumatoid arthritis
- Enhances collagen cross-linking

19

T or F, Pure gold is not toxic

True

20

Can Gold salts be toxic?

Yes, toxic to the liver and kidneys

21

Name the symptoms of Gold toxicity

1. Dermatitis
2. Metallic taste in mouth
3. Proteinuria
4. GI symptoms
5. Aplastic anemia

22

What is the antidote to Gold toxicity?

- Dimercaprol
- penicillamine

23

Mercury was used in the 1800's to help infants in what?

It was in teething powders for infants and to treat toothaches

24

What is Thiomersal

- Preservative found in vaccines
- It degrades to ethyl mercury
*Many thought this was link to autism with vaccines. No evidence to support this

25

Thiomersal has been removed from all vaccines or only in trace amounts for children under 6 years except one vaccine, what is the vaccine?

Inactivated influenza vaccine

26

Mercury can still be found in what OTC medicines?

- Topical antiseptics
- Stimulant laxatives
- Some dipaer rash ointments
- Eye drops
- Nasal sprays

27

With continuing exposure to mercury, a fine tremor develops. Describe the initial tremor:

Tremor initially involves the hands and later spreads to the eyelids, lips and tongue.

28

Effects experience from elemental mercury exposure:

- Neurotoxicity with neuropsychiatric effects
- Acute poisoning = pneumonitis

29

Effects of Inorganic mercury exposure:

- Corrosive to oral cavity and gut
- Kidney damage

30

What are the antidotes to mercury toxicity

1. N-acetyl-D,L penicillamine
2. Dimercaprol
3. penicillamine

31

What biochemical effect does lead poisoning have on the body

- Enzyme inhibitor in the production of heme
○ Inhibits protoporphyrin IX
Accumulation of aminolevulonic acid = diagnostic

32

What symptoms and effects occur in individuals with lead poisoning?

- Accumulates in CNS
- GI, CV effects
- Lead lines are visible in teeth in children

33

What are the antidotes to lead poisoning

- Combination: calcium EDTA and dimercaprol
*The combo is better than either alone

34

What might be some effects on the body long-term exposure to lead

- Nephropathy
- Abdominal pain
- Delayed puberty in girls
- Reduced cognitive capacity
- schizophrenia

35

T or F, There is no evidence linking Cadmium to cancer

False, cadmium is known to cause cancer

36

Cadmium poisoning is similar to what other heavy metal toxicity

- Lead poisoning
- Inhibits same processes as lead

37

Acute problems from cadmium poisoning

Pulmonary problems

38

Chronic problems from cadmium poisoning

- Emphysema, COPD
- Also goes into bones = reasonably non-toxic here

39

Antidote to cadmium poisoning

Dimercaprol and calcium EDTA

40

What is the risk of the antidote used to treat cadmium poisoning

Treatment mobilizes cadmium to the kidneys = possible renal toxicity

41

What is the exposure to iron from?

From ferrous sulfate tablets used in the treatment of iron-deficiency anemia

42

Name the symptoms of iron exposure

- GI irritation
- Pneumonitis
- Convulsions
- Coma
- Liver damage

43

Name the antidote to iron exposure

Deferoxamine

44

Mechanism of Deferoxamine

- Complexes with trivalent ions (Ferric ions) to form ferrioxamine, which is removed by the kidneys

45

Symptoms to Aluminum exposure

- Pots and pans senility
- Concern for assoc. with Alzheimer's disease
- End stage renal failure

46

Antidote for aluminum exposure

- Deferoxamine
- Aluminum chelating agents are given to reduce amount

47

How might one get nickel exposure:

Exposure from electronic, steel and mining industries

48

Symptoms of nickel exposure

- Dermatitis
- Nasal and respiratory cancer

49

Antidote for nickel exposure:

Diethylthiocarbamate trihydrate

50

Requirements for Heavy Metal Antagonists used as antidotes

1. Water solubility
2. Resistant to metabolic degradation
3. Small size (so excreted by kidney)
4. Chelate is stable at physiological pH
5. Chelate is less toxic than the ion
6. Bind the toxic metal better than it binds Ca+
**If not, risk for calcium deficiency

51

Dimercaprol is an antidote used in what toxicities?

- Arsenic
- Antimony
- Gold
- Mercury

52

Calcium disodium edelate (EDTA) is an antidote used in what toxicities?

- Lead
- Cadmium

53

Penicillamine has what function and is used as an antidote to what toxicities?

- Used long term to clear bone, skin and keratinized tissues of arsenic, antimony
- Gold
- Mercury

54

Deferoxamine is an antidote used for what toxicities?

- Iron
- Aluminum