Chelation Therapy

Question 1

Name a chelator that is solubilized in peanut oil and works best if given immediately? Use? Side effects?

Answer 1

British Anti-Lewisite (BAL) = [Dimercaprol]
USE: arsenic, lead and mercury poisoning
SE: Renal toxicity (due to dissociation of chelate)- IV bicarb needs to be given concurrently to alkalanize urine

Question 2

Name the most commonly used chelating agent for lead poisoning that is given orally. What other metals is it useful for? Side effects?

Answer 2

2,3-dimercaptosuccinic acid (Succimer)

USE: lead, arsenic, mercury, cadmium poisoning
SE: transient LFT elevation

Question 3

Which 2 chelating agents are dithiols?

Answer 3

British Anti-Lewisite (Dimercaprol)

2,3-dimercaptosuccinic acid (Succimer)

Question 4

What is the mechanism, use and side effects of CaNa2EDTA (Calcium Disodium EDTA)? What are 2 important concerns with this drug?

Answer 4

Lead poisoning –> displacement of calcium by lead
SE: renal toxicity

*Given IV; DO NOT CONFUSE WITH Na2EDTA (disodium EDTA) (can lead to life-threatening hypocalcemia); if given in lead encephalopathy, there is a potential to cause lead redistribution into the brain; BAL must be given before this in that scenario

Question 5

Name a chelating agent that is taken orally but is not absorbed and therefore has little side effects (“gut dialysis”). What metals is it used for?

Answer 5

Prussian blue

Thallium and radioactive cesium poisoning

Question 6

What is the use and mechanism of Deferoxamine? What is an important adverse effect with prolonged therapy?

Answer 6

USE: Acute iron poisoning; Chronic iron overload
–>chelates FREE iron and iron transported between transferrin and ferritin
SE: acute lung injury (can only treat for 24 hours before acute lung injury manifests)

Question 7

What do heavy metals bind to that cause multi-organ dysfunction and toxicity?

Answer 7

sulfhydryl groups