The Role of Chelation in the Treatment of Arsenic and Mercury Poisoning Original paper

What was studied?

This paper examines the role of chelation therapy in treating arsenic and mercury poisoning, particularly focusing on the efficacy of key chelating agents such as British anti-lewisite (BAL), DMPS (Unithiol), and DMSA (Succimer). The review traces the development of these chelators, their therapeutic use, and the effects of chelation on the elimination of arsenic and mercury from the human body. The study delves into the historical context of chelation therapy, starting with the creation of BAL during World War II for treating arsenic poisoning from lewisite, an arsenic-based chemical weapon. The article also explores the animal studies that demonstrated the efficacy of these chelating agents in acute exposure cases and discusses the limitations of chelation therapy for chronic exposure to these heavy metals.

Who was studied?

The review incorporates data from animal studies, controlled trials, and clinical case reports of arsenic and mercury poisoning, mainly focusing on the effects of chelation therapy in humans. The patients studied in clinical trials were exposed to inorganic arsenic and mercury, either through occupational exposure, environmental contamination, or industrial accidents. These studies aim to determine the practical application of chelation agents in human cases, especially in scenarios of chronic exposure, which presents a more complex challenge than acute poisoning. Additionally, the review includes information about historical clinical applications of BAL, especially its use in treating arsenic intoxication related to medical treatments in the mid-20th century.

Most important findings

The review provides insights into the clinical application of chelating agents in treating arsenic and mercury intoxication. BAL, DMPS, and DMSA have proven effective in acute poisoning, with studies showing significant improvements in arsenic excretion and survival rates when administered promptly after exposure. Notably, DMPS and DMSA offer a higher therapeutic index than BAL and do not redistribute arsenic or mercury to the brain, a significant advantage over BAL, which can cause such redistribution. However, the review highlights the limited success of chelation therapy in cases of chronic arsenic and mercury poisoning, where the efficacy of these agents in reducing long-term morbidity and mortality remains largely unproven.

The review further examines the impact of chelation on various biomarkers, such as urine arsenic levels, as well as the therapeutic limitations, especially when the treatment is delayed. Chelation therapy has been more successful in preventing acute toxicity, but its role in treating chronic poisoning remains less clear. Moreover, the study discusses the adverse effects associated with chelation therapy, including allergic reactions and gastrointestinal disturbances, which can complicate treatment regimens. The review concludes that while chelation is a vital tool in acute intoxication, its efficacy in chronic exposure remains uncertain, and further studies are needed to better understand its potential benefits and risks.

Key implications

The findings of this review have significant implications for the treatment of arsenic and mercury poisoning, particularly in clinical settings where patients may have been exposed to these metals for extended periods. While chelation therapy offers rapid and effective detoxification in acute poisoning cases, the efficacy of long-term treatment in chronic exposure scenarios requires more robust evidence. Clinicians must balance the benefits of chelation, such as increased excretion of toxic metals, with the risks of potential side effects and metal redistribution, especially when using agents like BAL. The review suggests that chelation therapy should be initiated as early as possible to achieve optimal results and reduce the severity of symptoms.