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[Pharmacology](https://durgical.com/en/pharmacology/) · Class

# Chelating agents

Molecules that grip a metal ion in a ring-shaped complex so the body can excrete it. Each one suits certain metals.

Updated 2026-11-01

## What they are

Drugs used in metal poisoning and overload. The name comes from the Greek and Latin word for claw: the drug closes around the metal. Iron chelators (deferoxamine, deferasirox, deferiprone) treat acute iron poisoning and transfusional iron overload; the sulfhydryl chelators (dimercaprol, succimer, penicillamine) and edetate calcium disodium treat lead, arsenic and mercury.

## Mechanism of action

The chelator offers the metal stronger binding than the body's own proteins (enzymes with sulfhydryl groups, ferritin). It forms a stable, water-soluble complex that is excreted in urine or bile. Chelation also moves metal between tissues, so it is combined and sequenced with care (in lead encephalopathy, dimercaprol is started before edetate).

Target: The metal ion itself (iron, lead, arsenic, mercury)

## Key points

- Iron: deferoxamine; the iron–deferoxamine complex turns urine reddish.
- Lead: succimer by mouth (milder cases, children); dimercaprol plus edetate calcium disodium for encephalopathy, with dimercaprol first.
- Dimercaprol is given intramuscularly and is not used for iron, because the complex is toxic to the kidney.
- Lead harms children's developing brain most; chelation never replaces removing the source of exposure.
- Activated charcoal does not bind metals.

## Drugs in this class

- [**Deferoxamine** An iron chelator given by injection for acute iron poisoning and for iron overload from repeated transfusions. The… Free iron and iron in ferritin and haemosiderin](https://durgical.com/en/pharmacology/deferoxamine/)
- [**Dimercaprol** An intramuscular chelator with two sulfhydryl groups that binds arsenic, mercury and lead. In lead encephalopathy it… Heavy-metal ions (arsenic, mercury, lead)](https://durgical.com/en/pharmacology/dimercaprol/)
- [**Sodium calcium edetate** An injectable chelator for lead: lead takes the place of calcium in the molecule and leaves in urine. It can harm the… Lead (and other divalent metals such as zinc)](https://durgical.com/en/pharmacology/sodium-calcium-edetate/)
- [**Succimer** An oral sulfhydryl chelator (DMSA) for lead poisoning, especially in children, and for arsenic and mercury. Lead, arsenic and mercury ions](https://durgical.com/en/pharmacology/succimer/)

## Others in the class

- Deferasirox
- Deferiprone
- Penicillamine
- Trientine

## Test yourself

Think of the answer, then tap the question to see it.

## Which chelator is used for acute iron poisoning?

Deferoxamine.

## In lead encephalopathy, which chelator is started first and why?

Dimercaprol, because edetate alone can move lead into the brain.

## Which oral chelator is preferred for lead poisoning in children?

Succimer (DMSA).

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Guía para el Manejo de Emergencias Toxicológicas](https://minsalud.gov.co/sites/rid/Lists/BibliotecaDigital/RIDE/DE/GT/guias-manejo-emergencias-toxicologicas-outpout.pdf) (Ministerio de Salud y Protección Social; Organización Panamericana de la Salud, 2017); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025); [Lead poisoning](https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health) (World Health Organization, 2026).

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