WASHINGTON (AP) — Anti-addiction activists are calling for the Food and Drug Administration's top official to step down, saying the agency's policies have contributed to a national epidemic of prescription painkiller abuse.

In a letter released Wednesday, more than a dozen groups ask the Obama administration's top health official to replace FDA Commissioner Dr. Margaret Hamburg, who has led the agency since 2009. The FDA has been under fire from public health advocates, politicians and law enforcement officials since last October, when it approved a powerful new painkiller called Zohydro against the recommendation of its own medical advisers.

The new letter is the first formal call for new leadership at the agency over the issue.

Hamburg has supported broad use of the drugs, noting that 100 million Americans reportedly suffer from chronic pain.

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