Chelating agents for lead poisoning

Examples

Dimercaprol is generally known as British anti-lewisite, or BAL.

Penicillamine has a chelating effect, but it is not used as often as calcium EDTA or BAL.

How It Works

These medicines:

• Bind lead in tissues and increase elimination of lead in the urine.
• Reduce blood lead levels.
• Reduce further harm from lead poisoning.

Why It Is Used

Chelating agents are used if:

• Blood lead levels are 45 mcg/dL or higher (in some cases, 20 mcg/dL or higher).
• Symptoms of lead poisoning are present.
• Lead encephalopathy is present.

Succimer is recommended for treating blood lead levels ranging from 45 to 70 micrograms per deciliter (mcg/dL) when there are no symptoms of lead poisoning. Succimer is given by mouth and is the treatment of choice if you can be treated at home. This drug is not approved to treat adults with lead poisoning (unlabeled use), yet adults have been treated with success.

A course of BAL followed by calcium EDTA, given while you are hospitalized, is recommended for blood lead levels of 70 mcg/dL or higher, or when there are symptoms of lead poisoning or lead encephalopathy.

Penicillamine is used if your child has unacceptable reactions to succimer and calcium EDTA. Like succimer, penicillamine is given in pills and can be taken at home. Treating lead poisoning with this drug is an unlabeled use. It has not been approved by the U.S. Food and Drug Administration (FDA) for this purpose.

How Well It Works

All chelating agents:

• Reduce blood lead levels.
• Reverse effects of lead poisoning on the blood.
• May cause the elimination of essential minerals, particularly calcium, magnesium, and zinc.

Side Effects

Succimer

• Abdominal pain
• Nausea
• Vomiting
• Diarrhea
• Chills
• Fever
• Hives
• Rashes

BAL

• Nausea
• Vomiting
• Fever
• Increases in blood pressure

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

• Lead sources in your home or workplace must be removed or reduced-or you need to be moved to a lead-safe home-before chelation treatment. If this is not possible, you must be hospitalized for treatment.
• Iron deficiency must be corrected either before or after chelation therapy, not at the same time. Chelation will bind to iron as well as lead and cause it to be eliminated, which can cause other health problems such as anemia.
• More than one course of treatment may be required to reduce blood lead levels.
• A lead blood test should be done a few weeks after each course of chelation.
• If a pregnant woman has a high blood lead level, the risk of exposing the fetus to chelating agents and to lead must be weighed. Referral to a center that specializes in lead toxicity is recommended.
• Treatment with calcium EDTA or BAL or both takes 5 to 10 days. Treatment with succimer takes 19 days. Treatment with penicillamine can take a few months.

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