Succimer found ineffective for removing mercury

Oct 22, 2010

Succimer, a drug used for treating lead poisoning, does not effectively remove mercury from the body, according to research supported by the National Institutes of Health. Some families have turned to succimer as an alternative therapy for treating autism.

"Succimer is effective for treating children with , but it does not work very well for ," said Walter Rogan, M.D., head of the Pediatric Epidemiology Group at the National Institute of Environmental Health Sciences (NIEHS), part of NIH, and an author on the paper that appears online in the .

"Although it is not approved by the to reduce mercury, succimer is reportedly being used for conditions like autism, in the belief that these conditions are caused, in part, by mercury poisoning," Rogan stated. "Our new data offers little support for this practice."

Although researchers found that succimer lowered blood concentrations of mercury after one week, continued therapy for five months only slowed the rate at which the children accumulated mercury. The safety of higher doses and longer courses of treatment has not been studied.

Most mercury exposure in the United States is from methylmercury, found in foods such as certain fish. Thimerosal, a preservative that was once more commonly used in vaccines, contains another form of mercury, called ethylmercury.

To conduct the study, the researchers used samples and data from an earlier clinical trial, led by NIEHS, called the Treatment of Lead-exposed Children (TLC) trial. In the TLC study, succimer lowered blood lead in 2-year-old children with moderate to high blood lead concentrations.

Using blood samples from 767 children who participated in the TLC trial, the researchers measured mercury concentration in the toddlers' blood samples collected before treatment began, one week after beginning treatment with succimer or placebo, and then again after three month-long courses of treatment. Mercury concentrations were similar in all children before treatment. Concentrations eventually increased in both groups, but more slowly in the children given succimer. Succimer had produced a 42 percent difference in blood lead, but only an 18 percent difference in blood mercury.

"Although succimer may slow the increase in blood mercury concentrations, such small changes seem unlikely to produce any clinical benefit," Rogan said. He and his colleagues had reported in an earlier paper that succimer has few adverse side effects, mostly rashes, and an unexplained increase in injuries in children given succimer rather than placebo.

The subjects of the study did not have unusually high blood mercury concentrations for African-American children and the study did not investigate where the mercury in the children came from.

"This research fills a gap in the scientific literature that could not be addressed any other way. We were fortunate to have samples already collected from toddlers who had been treated with succimer for lead poisoning allowing us to help answer this important question," said Linda Birnbaum, Ph.D., director of NIEHS and the National Toxicology Program.

Birnbaum noted NIH's commitment to supporting research that provides critically needed information that will help drive more prevention and treatment options for with and other neurodevelopmental disorders.

Explore further: Medical charity accuses US of pushing India to ease patent rules

More information: Cao Y, Chen A, Jones RL, Radcliffe J, Dietrich KN, Caldwell KL, et al. 2010. Efficacy of Succimer Chelation of Mercury at Background Exposures in Toddlers: A Randomized Trial. J Pediatr. Epub ahead of print. DOI:10.1016/j.jpeds.2010.08.036

Provided by National Institutes of Health

3 /5 (1 vote)
add to favorites email to friend print save as pdf

Related Stories

Mercury reduction tied to emissions laws

Apr 03, 2006

Seven years after Massachusetts passed the nation's toughest mercury emission incinerator laws, mercury found in some freshwater fish is down 32 percent.

Study: Mercury can travel long distances

Dec 12, 2005

University of Washington scientists say they may have determined why mercury in the atmosphere might be washed out more easily than earlier believed.

Recommended for you

Ebola vaccine not before late 2016: GSK researcher

Oct 17, 2014

An Ebola vaccine by British pharmaceuticals giant GlaxoSmithKline may not be ready for commercial use until late 2016 and should therefore not be seen as the "primary answer" to the current outbreak, a company researcher ...

Chimerix gets FDA OK to test drug for Ebola

Oct 17, 2014

(AP)—A North Carolina drugmaker plans to test its experimental antiviral drug in patients who have Ebola, after getting authorization from regulators at the Food and Drug Administration.

Esbriet, ofev approved to treat deadly lung disease

Oct 16, 2014

(HealthDay)—Two new drugs have been approved by the U.S. Food and Drug Administration to treat progressive lung scarring from an uncertain cause, medically called idiopathic pulmonary fibrosis (IPF).

FDA weighs removing bolded warning from Chantix

Oct 14, 2014

(AP)—The Food and Drug Administration will ask a panel of experts later this week whether a bold-letter warning on the anti-smoking drug Chantix should be removed based on company-supported evidence that the drug does not ...

Drug-coated balloon catheter approved

Oct 13, 2014

(HealthDay)—The first drug-coated balloon catheter designed to clear narrowed or blocked arteries in the thigh and knee has been approved by the U.S. Food and Drug Administration.

User comments : 0