http://www.newscientist.com/article.ns?id=mg18825295.000
A POPULAR over-the-counter painkiller is now the leading cause of acute liver failure in the US - and almost half of those cases are accidental overdoses.
Paracetamol (or acetaminophen as it is known in the US) is used by millions of Americans each year, and is commonly thought to be safe. Until 1980, paracetamol was not even listed as a cause of acute liver failure. But between 1998 and 2003, the proportion of cases of liver failure caused by the drug nearly doubled.
William Lee at the University of Texas Southwestern Medical Center in Dallas and his colleagues followed patients with acute liver failure who were in a coma. Of the 275 people with paracetamol poisoning, 8 per cent received a liver transplant, 65 per cent survived without one and 27 per cent died.
Initially the researchers had suspected a direct relationship between how much of the drug is in the liver and for how long, and the extent of the damage. But people who intentionally overdosed, who tend to be identified and treated more quickly, had similar damage to those who overdosed accidentally. That suggests a clear threshold for what constitutes a safe dose of the drug.
Many of the people who had accidentally poisoned themselves did so by taking just 10 grams of the medication each day for about three days - the equivalent of about 20 pills per day instead of the recommended eight, an overdose that might be less serious with other drugs. Other people had unwittingly taken two products that both contained the drug (Hepatology, vol 42, p 1364).
Lee thinks American drug enforcers should follow the lead of the UK, which requires products that contain acetaminophen to be packaged in blister packets and sold in small quantities. "I think we should talk about limiting package size," says Lee. "You can buy 500 at a time. They're like M&Ms."