Pharmacology · Chelating agents
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 kidney and raise brain pressure.
Updated 2026-11-01
Also called: Edetate calcium disodium, calcium disodium EDTA
Mechanism of action
The drug carries calcium, so it does not drain the body's calcium. Lead, which binds more tightly, displaces the calcium and forms a stable, soluble chelate excreted in urine. Most of the lead removed comes from bone; soft-tissue lead then moves back into bone. Given alone, edetate can shift lead into the brain, so in encephalopathy it is combined with dimercaprol, which is started first. It also increases zinc excretion.
- Lead displaces the calcium carried by edetate
- A stable lead chelate forms, mostly from bone lead
- The kidneys excrete the chelate
- With dimercaprol first, less lead moves to the brain
Pharmacokinetics
- Absorption
- Poorly absorbed by mouth; given intravenously or intramuscularly
- Distribution
- Extracellular fluid; it does not enter cells and little reaches the cerebrospinal fluid
- Elimination
- Kidneys, almost entirely within 24 hours; hardly metabolised
- Half-life
- 20 to 60 minutes
Indications
- Acute and chronic lead poisoning and lead encephalopathy (with dimercaprol in severe cases), in adults and children Lead poisoning →
Adverse effects
Common
- Malaise, fever, headache and loss of appetite
- Urinary frequency and urgency
- Transient hypotension
- Low alkaline phosphatase from zinc loss
Contraindications
- Anuria
- Active kidney disease
- Hepatitis
Key interactions
- Zinc-containing insulin preparations
- Edetate can chelate their zinc
What is monitored
- Urinalysis and urine sediment
- Kidney and liver function and electrolytes, before each course and during treatment
- Urine output throughout
- ECG during intravenous therapy
- Blood lead
Administration and safety
- Intramuscular route preferred in lead encephalopathy; if intravenous, never a rapid infusion
- Adequate urine flow is established before starting
- In encephalopathy, started after the first dimercaprol dose
- The recommended daily amount is never exceeded
Nursing care
- Measure urine output and report if it stops
- Watch for headache, vomiting or drowsiness in encephalopathy (rising intracranial pressure)
- Keep cardiac monitoring during intravenous infusion
- Help find and remove the lead source (paint, batteries, ceramics, work)
Pregnancy and breastfeeding
Data in pregnancy are limited and teratogenic effects have not been ruled out, so it is used only after weighing risk and benefit.
Test yourself
Think of the answer, then tap the question to see it.
Why does the antidote contain calcium?
So that it chelates lead (which displaces calcium) without depleting the body's calcium.
Why is dimercaprol started first in lead encephalopathy?
Edetate alone can move lead into the brain and worsen encephalopathy.
Which organ is most at risk during treatment?
The kidney: proteinuria, haematuria and tubular damage; urine output is monitored.
Related drugs
Related conditions
← Back to the class: Chelating agents
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - EDETATE CALCIUM DISODIUM injection (DailyMed (U.S. National Library of Medicine), 2026); Guía para el Manejo de Emergencias Toxicológicas (Ministerio de Salud y Protección Social; Organización Panamericana de la Salud, 2017); eEML - Electronic Essential Medicines List (World Health Organization, 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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