Dimercaprol

How it works

Its sulfhydryl groups bind heavy-metal ions to form stable complexes that are then excreted, reducing the metal available to inhibit cellular enzymes.

Prescribing in practice

• Avoid in iron, cadmium and selenium poisoning, where the resulting complexes are more toxic than the metal alone.
• Use with caution in hepatic impairment and in patients with glucose-6-phosphate dehydrogenase deficiency owing to the risk of haemolysis.
• It is given by deep intramuscular injection and commonly causes injection-site and systemic reactions.

Monitoring

Monitor blood pressure, heart rate, renal function and the patient's clinical response throughout treatment.

Counselling the patient

• Warn that injections may be painful and can cause flushing, nausea or a burning sensation.
• Explain that an alkaline urine may be encouraged to protect the kidneys, as advised by toxicology services.
• Advise reporting any worsening symptoms promptly.

Evidence & guidelines

Dimercaprol is an established chelator for arsenic, inorganic mercury and lead poisoning, with use directed by poisons information services.