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Pharmacology Unit 6 > Chelation Therapy > Flashcards

Flashcards in Chelation Therapy Deck (36)
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1


What are the signs of acute arsenic poisoning?


Long QTc and rice water diarrhea

2

In mercury poisoning, what is the Tx of choice?


Succimer

3


What is the general heavy metal mechanism of toxicty?


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

4


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

 

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

5


What is difficult about Dx chronic heavy metal exposure?


Subtle findings

6


What are important steps in making a heavy metal Dx?

 

  • PE
  • Question occupation/hobbies
  • Labs
  • Serum metal levels

7


What are the top 4 heavy metal considerations?

 

  • Lead
  • Arsenic
  • Mercury
  • Thallium

8


What is a chelating agent?


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

9


What is a chelate?


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

10


What ligands do lead and mercury bind best to?


Sulfur and Nitogen

11


What ligands does calcium bind best to?


Oxygen

12


What is the determinant of the chelator efficacy?


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

13


What are the characteristics of an ideal chelator?

 

  • 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

14


What is another name for dimercaprol?


British Anti-Lewisite

15


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


Mixed with peanut oil, which carries allergic implications

16


What type of metal poisoning is BAL useful for?


Arsenic, Lead, Inorganic Mercury

17


Adverse effects of BAL?

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

18


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


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

19


What is another name for DMSA?


Succimer

20


What is Succimer used to treat?

 

  • Lead
  • Arsenic
  • Mercury
  • Cadmium

21


Adverse rxns to Succimer


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

22


What is Edetate Calcium Disodium used to treat?


Primarily lead

23


What are the adverse reactions to edetate calcium disodium?


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

24


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


Sodium EDTA is prescribed instead causing accidental hypocalcemia

25


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


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

26


Side effects of Prussian BLue?


Not absorbed after oral dosing, well-tolerated

27


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


Iron is a free cation in the blood in OD situations

28


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


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

29


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


Direct corrosive GI toxicity and systemic toxicity

30


Describe the pathogenesis of Fe toxicity

 

  • 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