Acetaminophen: Common Painkiller May Ruin Your Liver

The authors of the study, which is appearing in the December issue of Hepatology, say the combination of acetaminophen's quiet ubiquity in over-the-counter remedies and its pairing with narcotics in potentially addictive drugs like Vicodin and Percocet can make it too easy for some patients to swallow much more than the maximum recommended dose inadvertently.

"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 gastroenterologist with the liver transplant program of the University of California at San Francisco. "Most 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 over-the-counter and prescription drugs with acetaminophen.

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 grisly 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 assault by the drug over several days. "I see some young women who have been suffering flulike symptoms for the better part of a week, and not eating much," Dr. Davern said. "They start with Tylenol, and maybe add 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."

Each Extra Strength Tylenol tablet contains half a gram, or 500 milligrams, of acetaminophen, and arthritis-strength versions of the pain reliever contain 650 milligrams. One tablet of Midol Teen formula contains 500 milligrams of acetaminophen, as does one adult dose of NyQuil Cold and Flu. 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 crummy," 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.

McNeil Consumer & Specialty Pharmaceuticals, a division of Johnson & Johnson, updated the labeling on all its Tylenol products in 2002 to list all the active ingredients on the front of the bottle, increase the type size of acetaminophen, and added a label on the front warning consumers not to use the product with others that contain acetaminophen, said Kathy Fallon a spokeswoman.

"I urge consumers to read the label," she said. "Anything more than the recommended dose is an overdose."

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."

In fact, the drug, when given in precise, appropriate doses is safer for children and teenagers than aspirin, which can interact with a viral infection to bring on rare but serious damage to the brain, liver and other organs in a constellation of symptoms known as Reye's syndrome. And among adults, low doses of acetaminophen are less likely than aspirin, ibuprofen or naproxen to eat away at the stomach, aggravate bleeding or harm the kidneys.

Even patients with chronic liver disease are justly advised to take acetaminophen for the occasional fever, or for the pain of osteoarthritis, a back injury or other malady, if they keep the total daily dose under about two grams, Dr. Lee said.

Experts agree that a vast majority of people can safely take the four-gram daily maximum that labels recommend for adults - the equivalent of eight Extra Strength Tylenol spread across 24 hours - and some people swallow much more without harm.

But by eight grams in a single day, a significant number of people whose livers have been stressed by a virus, medication, alcohol or other factors would run into serious trouble, Dr. Lee said. Without intervention, about half the people who swallowed a single dose of 12 to 15 grams could die.

How much alcohol over what time period is problematic? Recent research suggests the answer isn't simple. The package labels now warn anyone who drinks three or more drinks every day to consult a doctor before taking acetaminophen, but Dr. Lee thinks that people who are sober during the week but binge on weekends may be vulnerable, too.

The few days of fasting that can accompany a bad stomach bug also seem to increase the liver's vulnerability to acetaminophen. And though safe levels of the drug for large men may, in general, be higher than those for small women, obese people aren't protected; extra fat in the liver seems to prime the organ for further damage.

Nearly two-thirds of the people in the transplant center study who unintentionally poisoned themselves were taking one or another of the roughly 200 prescription drugs that contain acetaminophen plus an opiate. Among the most popularly prescribed drugs in this group include hydroconebitartrate plus acetaminophen, which is commonly sold as Vicodin, and oxycodone hydrochloride plus acetaminophen, better known as Percocet.

While these acetaminophen/opiate combination drugs can be very effective in curbing pain after surgery or injury, some patients who take the drugs chronically soon find they need increasing amounts to achieve the same level of pain relief.

Because the narcotic part of the compound can be addictive, its accompanying doses of acetaminophen climb sky high in lock step. The liver may keep pace with gradual increases of the drug initially, only to suddenly crash months later. It is the acetaminophen that kills the liver.

Lynne Gong of San Jose, Calif., watched her 28-year-old daughter, Leah, nearly die last summer after that sort of crash. What had started out as a treatment for the pain of a dislocated shoulder and subsequent surgery had escalated over two years to a full-blown addiction.

After her daughter was hospitalized, Ms. Gong said she found herself warning friends, neighbors "and anyone else who would listen" that they needed to closely monitor their own intake of acetaminophen and that of their children.

Some dangers lurk in surprising corners. One day, after Lynne Gong told the women in her prayer group about Leah's experience, a member went home and, after a little investigating of her own, discovered that her 12-year-old son and his friends had started nipping NyQuil on Friday nights for the alcohol content, in hopes of getting drunk.

There are 9.8 grams of acetaminophen in a 10-ounce bottle of NyQuil, Ms. Gong said. "Everyone really needs to be more aware."
 
Source: http://www.nytimes.com/