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Pharmacology Unit 6 > Chelation Therapy > Flashcards

Chelation Therapy Flashcards

1
Q

What are the signs of acute arsenic poisoning?

A

Long QTc and rice water diarrhea

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2
Q

In mercury poisoning, what is the Tx of choice?

A

Succimer

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3
Q

What is the general heavy metal mechanism of toxicty?

A

Bind to sulfhydryl groups in various organ systems and enzymatic processes throughout the body

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4
Q

On what organ systems does acute metal toxicity manifest and how?

A
  • Cardiovascular - tach. and cardiomyopathy
  • CNS - Altered mental status, peripheral neuropathy
  • GI - N/V/D
  • Renal - Proteinuria, aminoaciduria, ATN
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5
Q

What is difficult about Dx chronic heavy metal exposure?

A

Subtle findings

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6
Q

What are important steps in making a heavy metal Dx?

A
  • PE
  • Question occupation/hobbies
  • Labs
  • Serum metal levels
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7
Q

What are the top 4 heavy metal considerations?

A
  • Lead
  • Arsenic
  • Mercury
  • Thallium
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8
Q

What is a chelating agent?

A

Forms complexes with heavy metals and prevents/reverses binding of metallic cations to reactive groups

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9
Q

What is a chelate?

A

Complex formed with the metal and chelator; 5/6 member rings are the most stable

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10
Q

What ligands do lead and mercury bind best to?

A

Sulfur and Nitogen

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11
Q

What ligands does calcium bind best to?

A

Oxygen

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12
Q

What is the determinant of the chelator efficacy?

A

RElative affinity of the chelator for the metal and distribution of the chelator compared with the distribution of the metal

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13
Q

What are the characteristics of an ideal chelator?

A
  • Chelator has a greater volume of distribution than the chelate
  • High water solubility
  • Resistant to biotransformation
  • Ability to reach site where metal is stored
  • Capacity to form non-toxic complexes
  • Stable at physiologic pH
  • Low affinity for trace elements
  • More stable than the endogenous chelate
  • Stable at physiologic pH
  • Resistant to biotransformation
  • Water soluble
  • Readily excreted
  • Nontoxic
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14
Q

What is another name for dimercaprol?

A

British Anti-Lewisite

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15
Q

What is BAL suspended in, and why is this a concern?

A

Mixed with peanut oil, which carries allergic implications

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16
Q

What type of metal poisoning is BAL useful for?

A

Arsenic, Lead, Inorganic Mercury

17
Q

Adverse effects of BAL?

A
  • Pain at injection site
  • N/V
  • Transient increase in BP and HR
18
Q

What is an important concurrent treatment that must occur when administering BAL?

A

Urinie must be alkalinized because BAL-metal chelate dissociates in acidic urine!

19
Q

What is another name for DMSA?

A

Succimer

20
Q

What is Succimer used to treat?

A
  • Lead
  • Arsenic
  • Mercury
  • Cadmium
21
Q

Adverse rxns to Succimer

A

Although relatively well-tolerated, N/C/Flatus/Diarrhea, Mild Elevations in AST and ALT

22
Q

What is Edetate Calcium Disodium used to treat?

A

Primarily lead

23
Q

What are the adverse reactions to edetate calcium disodium?

A

Principal toxicity due to the metal chelate - leading to renal toxicity, malaise, fever, AST/ALT elevatiaon

24
Q

What is a medication error that occurs with Edetate calcium disodium?

A

Sodium EDTA is prescribed instead causing accidental hypocalcemia

25
Q

How does Prussian Blue work? What metals does it chelate?

A

Enters GI system and binds Thallium and Cesium (Is not absorbed into body)

26
Q

Side effects of Prussian BLue?

A

Not absorbed after oral dosing, well-tolerated

27
Q

What compartment of the body is iron contained in during an iron OD?

A

Iron is a free cation in the blood in OD situations

28
Q

After iron is absorbed, why are iron cations free in solution?

A

Massive amounts of iron overwhelm transferrin and therefore there is an increased circulation of free iron

29
Q

What are the two major types of toxicity that occur in Fe overload?

A

Direct corrosive GI toxicity and systemic toxicity

30
Q

Describe the pathogenesis of Fe toxicity

A
  • Ferrous oxidized to ferric resulting in H+ liberation and acidosis
  • High concentrations of Fe in mitochondria uncouple ox phos resulting in lactic acid and AG acidosis
31
Q

What direct cardiovascular effects does iron toxicity have?

A
  • Direct negative inotropic effect
  • Vasodilation and further hTN
32
Q

What is an important clinical sign that someone has iron toxicity?

A

Multiple bouts of nausea and vomiting w/i 6 hours of poisoning

33
Q

What are the most important tests to make a Dx of iron poisoning?

A

Assessment of acid-base balance, acute blood loss

Iron toxicity is a clinical Dx

34
Q

What chelator is used to treat iron tox?

A

Deferoxamine

35
Q

How does deferoxamine work?

A

Chelates ferric iron and is excreted in urine as ferrioxamine

36
Q

What are the adverse SEs of Deferoxamine?

A
  • Rate-related hTN
  • Anaphylactoid rxn
  • Facilitates growth of unusual organisms (Yersinia enterocolitis)
  • Acute Lung Injury

Pharmacology Unit 6 (15 decks)

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