Chelating Agents
Transcript of Chelating Agents
CHELATING AGENTS
• from the greek word “claw”
• First chelating agent: BAL (british anti-lewiste)
CHELATION: organic molecules which form stable complexes with metal ions. Usually water soluble.
POISON ANTIDOTE COMMMENTS
Acetaminophen Acetylcystiene Given before 24 hours ingestion activated charcoal
Lead Calcium-EDTA Chelating agent
arsenic?/ other metals DimercaprolD- penicillamine
Chelating agent
Lead, mercury, arsenic
succiner Chelating agent
Chelating agents
• Drugs that prevent or reverse toxic effect of heavy metal on an enzyme or other cellular target.
• Determined by number of ligands groups. The greater the number, the stable the metal chelator complex.
DIMERCAPROL
• ( 2,3-dimercaptopropanol)• Also known as BAL : prototype• Given after Asenic exposure• IM/ often painfulTOXICITY: contraindicated in CHRONIC
POISONING (may redistribute mercury and
arsenic)
SUCCIMER
• (dimercaptosuccimic acid, DMSA)• Water analog of dimercaprol• Excreted in urine• USA: oral prepartion available.
Other place is IV.• Peaks at 3hours• Half life: 2-4 hours
mech: binds to ammino acid cystiene to form 1:1 and 1:2 mixed disulfide increasing excretion.
ADV: G.I. Problem, rashes, n/v, anorexia
EDTA• (ethylene diaminetetraacetic acid)• To prevent depletion of calcium,
preparation should only be CALCIUM DISODIUM SALT.
• I.V. Infusion• Contraindicated for anuria patient
2004: EDTA is FDA approved used to uranium ,plutonium , americanium, curium.
UNITHOL
• (dimercaptopropanesulfonic acid)DMPS• Water soluble to dimercaprol• 1st used in Russia(1958)/ used in USA
(1994)
• Bioavailability: oral (50%) peak:3-7 hr I.V. (80%) peak:20
hr
• Used against mercury, arsenic, lead.
TOXICITY: aqueous preparation (50mg/kg in sterile water every 4 hours over 20 mins (slow I.V.)
Oral Unithol: alternative use for succiner
• Adverse: limited to dermatologic reaction
-urticaria -Erythema multiform-Steven – Johnson syndrome
Note: rapid infusion can cause hypotension
PENICILLAMINE• (D-dimethycystiene)• White crystalline, water derivative of
penicillin• Readily absorbed on GUT and
Metabolic degradationIndication: copper poisoning (wilsons
dse) severe rheumatoid arthritisAdv: hypersensitivity/nephrotoxicity
DEFEROXAMINE• Isolated from STREP. PILOSUS
• Chelator of choice for iron poisoning
• Deferoxamine + hemodialysis = tx for aluminum toxicity of renal
failure
• may increase iron absorption if given orally
• Pathway is unknown
• Excreted in urine and causes ORANGE-RED color.
ADV:• Rapid I.V. = hypotension• Idiosyncratic reaction• Pulmonary comlication an
susceptibilty to infection ( seen in long term use)
PRUSSIAN BLUE
• (ferric hexacyanoferate )• Hydrated crystalline compund in
which Fe atoms are coordinated with cyanide groups in a cubic lattice structure.
MECH of ACTION: ion-exchange/ mechanical trapping on adsorption to certain univalent cations
• For cesium/ thallium• Elimination via fecesINDICATION: 2003- FDA approved
treament for cesiumDosage: 3g orally 3x/daySerial monitoring/ fecal and urineContipation mmay occur
Reference
• Bertman G. Katzung (lange)
• John joseph fenton ( toxicology)
• Steven G. Gilbert (a small dose of toxicology)
THANK YOU