Sodium Calcium edetate

Sodium Calcium Edetate (EDTA) is an intravenous heavy metal chelating agent. EDTA is primarily used in the treatment of severe lead poisoning with or without lead encephalopathy or an asymptomatic/mildly symptomatic patient with a serum lead level >70 microgram/dL (3.38 micro mol/L).

EDTA is second line to succimer as a chelator and should not be used if the patient is anuric

Administration

Lead encephalopathy:

• Commence dimercaprol (BAL) at 4 mg/kg IM every 4 hours and continue for 5 days.
• Dilute EDTA 50-75 mg/kg in 500 ml of 0.9% saline of 5% dextrose and infuse over 24 hours starting 4 hours after the first dose of dimercaprol

Symptomatic lead poisoning without encephalopathy:

• Commence dimercaprol (BAL) at 3 mg/kg IM every 4 hours and continue for 5 days.
• Dilute EDTA 25-50 mg/kg in 500 ml of 0.9% saline of 5% dextrose and infuse over 24 hours starting 4 hours after the first dose of dimercaprol

EDTA therapy is usually continued for a maximum of 5 days or in the setting of encephalopathy until the patient is clinically stable. Therapy is then interrupted for 2 to 4 days to allow redistribution of the lead prior to consideration of a further 5-day course.

Once clinically improved, chelation may be switched to oral succimer if tolerated.

Adverse reactions:

• Local pain and thrombophlebitis
• Malaise, fatigue, myalgia, dermatitis, headaches, lacrimation, urinary frequency.
• Hypotension
• Transaminase elevations
• ECG changes
• Nephrotoxicity secondary to dissociation of EDTA-metal complexes in acidic urine – reduced by ensuring adequate hydration and urinary flow 1-2ml/kg/hour.

References

• Bradberry S, Vale A. A comparison of sodium calcium edetate (edetate calcium disodium) and succimer (DMSA) in the treatment of inorganic lead poisoning. Clinical Toxicology 2009; 47:841-858.
• Treatment guidelines for lead exposure in children. Committee on Drugs. Pediatrics 1995; 96: 155-160.