Inhibition of Warfarin Anticoagulation Associated with Chelation Therapy

Heidi Braun Grebe, Pharm.D., Philip J. Gregory, Pharm.D.


Pharmacotherapy. 2002;22(8) 

In This Article

Abstract and Introduction

Chelation therapy originally was administered exclusively to patients with heavy metal poisoning. Now some physicians are administering this therapy for numerous conditions, most commonly coronary heart disease. A 64-year-old man experienced impaired warfarin anticoagulation after undergoing chelation therapy. His international normalized ratio (INR) fell from 2.6 the day before to 1.6 the day after therapy was administered. Whether chelation therapy decreases the effectiveness of warfarin anticoagulation is uncertain. However, because of this potential interaction, clinicians should consider increased INR monitoring in patients undergoing chelation therapy.

Chelation therapy originally was intended for treating patients with heavy metal poisoning. The compounds, including ethylenediamine-tetraacetic acid (EDTA) and dimercaptopropane sulfonate, indiscriminately bind and remove minerals and metals such as aluminum, arsenic, cadmium, copper, lead, nickel, and mercury from the body. Administration of chelation therapy expanded to other conditions, such as heart disease, in the 1950s. While treating workers in the battery industry for lead accumulation, Norman Clarke, Sr., M.D., noticed that some patients had improved angina after chelation therapy.[1,2] In theory, progression of athero-sclerosis depended on copper, iron, or other minerals, such as calcium, and chelation therapy could bind these minerals and inhibit the process. Chelation therapy for patients with heart disease fell out of favor in the 1960s. In 1972, the remaining proponents of chelation therapy founded the American College for the Advancement of Medicine to promote and perform research on chelation therapy.[2] Today, more than 1000 physicians practice chelation therapy in the United States.[1,3] However, whether the potential benefits of this therapy outweigh the risks still remains highly controversial.

Our patient experienced impaired warfarin anticoagulation after treatment with chelation therapy. To our knowledge, this case report is the first to describe this occurrence.