Chelation therapy refers to the use of chelating drugs for the treatment of metallic poisoning and neurotoxicity due to other causes. Chelation therapy may be required for clearing gadolinium deposits resulting from use of contrast agents for MRI. Chelating agents are also used for the treatment of neurologic disorders where metals play a part in the pathogenesis. Penicillamine, a copper chelator, is well known for the treatment of Wilson disease. Several other chelating agents and their use for the treatment of neurologic disorders are described in this article. Evidence is accumulating that interactions between beta-amyloid and copper, iron, and zinc are associated with the pathophysiology of Alzheimer disease. Clioquinol as chelation therapy was in clinical trials for the treatment for Alzheimer disease, but further development was discontinued. Study of deferoxamine has been suggested for treatment of neoplasms of the nervous system.
| || |
• Chelation therapy refers to the use of chelating agents for the treatment of metallic poisoning.
| || |
• Neurologic disorders associated with accumulation of metals can benefit from agents that remove these metals.
| || |
• Chelating agents such as edetate calcium disodium may also be useful for the management of neurotoxicity associated with adverse effects of therapeutic drugs and neurodegenerative disorders.
| || |
• Some MRI contrast agents containing metals that can deposit in the brain require chelation therapy for removal of these metals.
| || |
• Brain requires an optimal concentration of metals for normal function, and the role of metal in the nervous system should be taken into consideration before chelating that metal.
| || |
• Some chelating agents are contraindicated diseases such as renal insufficiency, and their use should be avoided in the presence of these diseases.
Historical note and terminology
Chelation therapy refers to the use of chelating drugs for the treatment of metallic poisoning. The term “chelator” stems from the Greek word chele, meaning claw. The chelating drugs bind the metal between 2 or more functional groups to form a metal-drug complex, which is then excreted through urine.
The history of modern chelation therapy begins during World War II, with the development of the British anti-Lewisite as an antidote against arsenic-containing lewisite gas. Anti-Lewisite use was later expanded to cover other metallic poisoning. D-penicillamine, a chelating agent for copper, was introduced for the treatment of Wilson disease in the 1950s (39).
This article describes the pharmacological basis of the use of chelating agents for heavy metal poisoning involving neurotoxicity. Chelating agents differ from other agents such as activated charcoal, which does not bind metals and is of limited use in metallic poisoning.
The action of drugs for some neurologic disorders, in which heavy metal toxicity is implicated, may involve chelating effect. An example is use of clioquinol for Alzheimer disease. Chelating agents may also be useful for the management of neurotoxicity associated with adverse effects of therapeutic drugs and neurodegenerative disorders.