If Acetaminophen Causes ADHD, Regulators Won’t Be Ready To Do Anything About It

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Add attention deficit hyperactivity disorder (ADHD) to the list of ailments attributed to the popular painkiller acetaminophen. A new study in the journal JAMA Pediatrics found that more than half of mothers who took acetaminophen during pregnancy were more likely to have children with ADHD-like behavior or hyperkinetic disorder, a severe form of ADHD.

It’s unclear at this point whether acetaminophen use is actually causing these symptoms or if both are a sign of other unnoticed factors, as the Globe and Mail pointed out. And the long, shameful history of blaming and criminalizing pregnant women for pretty much anything they do during pregnancy means this news should be taken carefully. But even if proof of a causal link is demonstrated, the FDA’s record on regulating over-the-counter (OTC) drugs, specifically acetaminophen, shows it wouldn’t be up to the job of dealing with it.

And this news comes just as the Food and Drug Administration (FDA) announced it would be revamping its process for approving and regulating over-the-counter drugs, in response to just such concerns that it’s too slow to respond to new products and safety issues.

Acetaminophen is one such failure, as ProPublica extensively documented in September. The FDA convened a panel of experts to evaluate its safety in 1977, as the drug was first becoming widely popular. The panel determined it was “obligatory” to include a label warning that acetaminophen could cause “severe liver damage.” The FDA didn’t add that warning until 2009.

Acetaminophen is both one of the most commonly-used pain relief drugs in the United States and the primary cause of acute liver failure, nearly half of all cases. Overdoses kill an estimated 458 Americans each year, and are responsible for more than 56,000 emergency room visits and 2,600 hospitalizations.

No painkiller or drug is without risk. But for comparison, the entire class of drugs that includes ibuprofen, the Advil ingredient that is similarly popular to acetaminophen, was responsible for 15 deaths in 2010, according to CDC data as reported in ProPublica. In the same year acetaminophen killed 321, 166 of which were accidental overdoses.

The main problem is that the difference between a therapeutic dose and a life-threatening one is small. The FDA recommends a maximum daily dose of four grams, and allows over half a gram per pill, meaning just eight pills taken in a 24-hour period could put someone over the limit. It’s unclear at what level serious liver damage occurs, and it seems to vary widely by individual, but many cases of injury have been documented under six, five, or even four grams per day. And a wide variety of OTC medications contain the drug, making it easy to double up accidentally by taking, say, cough liquid with cold pills, or flu medicine with pain pills.

But the case of prescription pain medication actually highlights the broader failures of OTC regulation. The FDA successfully limited prescription drugs to a third of a gram of acetaminophen per pill in 2011, half the amount allowed in OTC drugs. And the agency recently announced it would move “hydrocodone combination products” that mix the opiate hydrocodone with acetaminophen from Schedule III to Schedule II, making them harder to prescribe. That’s in response to the risk of addiction and opioid overdose, but it also addresses the fact that the acetaminophen could potentially cause overdose first.

In 2009, an FDA panel endorsed a variety of measures to make OTC acetaminophen safer against strenuous industry objections, including lowering the maximum daily dose from four grams, getting rid of high-dose formulations, and restricting packages to smaller quantities of pills. These changes have not yet been implemented.