Paper II — 2023 March (Supplementary) (2010 Scheme) — Q7

Paper II

2023 March (Supplementary) (2010 Scheme)

Question

Chelating agents

Q73 marksShort Notes★✓

Answer

Chelating agents bind metal ions with multiple electron-donor groups (oxygen, nitrogen, or sulfur atoms), forming a stable, water-soluble complex that is then renally (or biliary) excreted, rendering the metal pharmacologically inert.

Classification by metal targeted

Metal	Chelating agent(s)
Lead	EDTA (edetate calcium disodium), Dimercaprol (severe cases), Succimer (oral)
Iron	Deferoxamine (parenteral, acute poisoning), Deferasirox (oral, chronic overload)
Copper	Penicillamine (Wilson’s disease), Trientine
Arsenic/mercury/gold	Dimercaprol (BAL)

Mechanism examples: EDTA is given as calcium-EDTA specifically so lead displaces the pre-bound calcium (preventing dangerous hypocalcemia); dimercaprol’s two adjacent thiol groups give it affinity for thiophilic metals and, being lipid-soluble, it can cross the blood-brain barrier (useful in lead encephalopathy, unlike water-soluble EDTA).

Adverse effects: dimercaprol — contraindicated in G6PD deficiency (hemolysis risk), pain at injection site; penicillamine — bone marrow suppression, proteinuria, drug-induced lupus-like syndrome.

Related Concepts

1. 1Chelating Agents

Other Years Asked

1. 1d-penicillamine2022 February (2019 Scheme)Short Answer · 4 marks
2. 2Write briefly on chelating agents.2024 December (Supplementary) (2019 Scheme)Short Answer · 4 marks
3. 3Chelating agents2025 March (Supplementary) (2010 Scheme)Short Note · 3 marks
4. 4Suppose this lady develops acute iron poisoning, the therapy which can be given is:2024 December (Supplementary) (2019 Scheme)MCQ · 1 mark
5. 5Rheumatoid arthritis2013 September (Supplementary) (2010 Scheme)Short Answer · 1 mark
6. 6Penicillamine2018 February (2010 Scheme)Short Answer · 1 mark
7. 7Chelating agents2016 February (2010 Scheme)Short Answer · 1 mark
8. 8Penicillamine in Wilson’s disease2019 February (2010 Scheme)Short Answer · 1 mark
9. 9Chelating agents2025 August (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
10. 10Antidote for iron poisoning2022 October (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
11. 11Iron chelating agents2020 February (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
12. 12Chelating agents.2022 July (Supplementary) (2019 Scheme)Short Answer · 0.2 marks
13. 13Drugs for treating Lead poisoning.2023 July (Supplementary) (2019 Scheme)Short Answer · 0.2 marks