Acetaminophen（乙酰氨基酚), the Unawared PoisoningDespite more than a decade's worth of res
Acetaminophen(乙酰氨基酚), the Unawared Poisoning
Despite more than a decade's worth of research showing that taking too much of a popular pain reliever can ruin the liver, the number of severe, unintentional poisonings from the drug is on the rise, a new study reports. The drug, acetaminophen, is best known under the brand name Tylenol. But many consumers don't realize that it is also found in widely varying doses in several hundred common cold remedies and combination pain relievers.
The authors of the study, which is appearing in the December issue of Hepatology(肝病学), say the combination of acetaminophen can make it too easy for some patients to swallow much more than the maximum recommended dose carelessly.
"It's extremely frustrating to see people come into the hospital who felt fine several days ago, but now need a new liver," said Dr. Tim Davern, one of the authors and a doctor with the liver transplant program of the University of California at San Francisco. "Most of them had no idea that what they were taking could have that sort of effect." The numbers of poisonings, however, are still tiny in comparison with the millions of people who use overthe-counter and doctor prescription drugs with acetaminophen.
Cases of Acetaminophen Poisoning
Dr. Davern and a team of colleagues from other centers led by Dr. Anne Larson at the University of Washington Medical Center in Seattle, tracked the 662 consecutive patients who showed up with acute liver failure at 23 transplant centers across the United States from 1998 to 2003.
Acetaminophen poisoning was to blame in nearly half the patients, the scientists found. The proportion of cases linked to the drug rose to 51 percent in 2003 from 28 percent in 1998. Not all the poisonings were accidental. An estimated 44 percent were suicide attempts by people who swallowed fistfuls of pills. "It's a horrible way to die," Dr. Davern said, adding that patients who survive sometimes suffer profound brain damage.
But in at least another 48 percent of the cases studied, the liver failed after a smaller, unintentional attack by the drug over several days. "I see some young women who have been suffering flu like symptoms for the better part of a week, and not eating much." Dr. Davern said. "They start with Tylenol, and maybe odd an over-the-counter flu medicine on top of that, and pretty soon they've been taking maybe six grams of acetaminophen a day for a number of days. In rare cases that can be enough to throw them into liver failure."
The Labeling Must Be Improved
Each Extra Strength Tylenol tablet contains half a gram, or 500 milligrams, of acetaminophen. One dose of Tylenol Cold and Flu Severe contains 1,000 milligrams. The recommended maximum daily dose for adults is 4 grams, or 4,000 milligrams.
"Part of the problem is that the labeling on many of these drugs is still far from satisfactory," said Dr. William Lee, a liver specialist at the University of Texas Southwestern Medical Center in Dallas, who for years has been lobbying the Food and Drug Administration to make manufacturers put "acetaminophen" in large letters on the front of any package that contains it, so that as they reach for the bottle, patients will be more likely to pause and keep track of exactly how much they are swallowing.
Some companies have voluntarily added new warnings about acetaminophen's risk to the liver, and they should be given credit for that, said Dr. Charles Ganley, director of the F.D.A's Office of Nonprescription Products. "But labeling isn't where I would like it to be." Dr. Ganley added.
Dr. Lee said he was disturbed by a pattern: "that acetaminophen is always billed as the one to reach to for safety, probably even more so now, with other pain relievers pulled from the market."
Safe Use of Acetaminophen
In fact, the drug, when giv
A．Y
B．N
C．NG
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