Chelation therapy

Chelation therapy is the administration of a drug that removes toxic metals from the bloodstream. Physicians have used chelation therapy since the 1950s to treat heavy metal poisoning--primarily lead poisoning--and to remove metalsthat have built up in tissues as a result of such genetic disorders as Wilson's disease, cystinuria, and hemochromatosis.

In addition to these accepted uses, chelation therapy has also been promotedby some as a non-surgical alternative for the treatment of atherosclerosis. However, no controlled scientific study has yet supported these claims and most physicians do not recommend chelation therapy for this purpose.

Chelation therapy is generally only recommmended when high levels of metal are present in the blood, since it does not seem to benefit those with lower levels. Currently, four drugs are used for chelation therapy: edetate calcium disodium (calcium EDTA), dimercaprol (BAL), succimer, and d-Penicillamine. Calcium EDTA is usually injected into a muscle, but it can be administered through a vein. BAL is injected into a muscle and is usually used along with calcium EDTA for the treament of lead poisoning. Because the muscular injection ofthese two drugs can be painful, they are normally administered with a localanesthetic (numbing medication). Succimer and d-Penicillamine are given in pill form.

The dosage of chelation therapy depends upon which drug is being used, the type and level of metal present in the patient's blood, and the patient's age and general health. If calcium EDTA is given on its own or with BAL, one treatment will last approximately five days with doses being given 4-12 hours apart. A second treatment may be administered after a two-day interval. If BAL isbeing given on its own, treatment will last approximately two weeks with doses being given 4-12 hours apart. Treatment with succimer takes about 19 days,while treament with d-Penicillamine may last as long as six months, particularly if the drug is being used to remove heavy metals that have accumulated in the blood because of a genetic disorder.

Patients who are pregnant or who have severe kidney problems, very low urineoutput, or very low blood circulation should not be given edetate calcium disodium (calcium EDTA). Patients with abnormally low levels of the enzyme glucose-6-phosphate dehydrogenase should not be given BAL, since the drug can trigger a breakdown of the red blood cells (hemolysis) in these persons. BAL should also not be given to patients who are allergic to peanuts, since the drugis mixed with peanut oil before it is administered. Finally, patients who areallergic to penicillin should not be given d-Penicillamine.

High doses of calcium EDTA can cause kidney damage. However, this can be reversed when the patient stops taking the drug. High doses may also cause headache, fever, chills, nausea, and vomiting. An irregular heartbeat may also be experienced when this drug is rapidly injected into a vein. Treament with BALmay produce a mild fever, nausea with occasional vomiting, and an increase inliver enzymes. It also may cause allergy-like symptoms, such as a runny noseand watery eyes, which can be alleviated by antihistamines. Succimer can produce mild nausea, fever, chills, and a skin rash. D-Penicillamine can cause an allergic reaction, particularly in persons sensitive to penicillin.

Iron supplements should not be taken while BAL is being administered, since the interaction between the two can cause severe vomiting.

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