Acetaminophen overdose leading liver failure cause

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Acetaminophen overdose leading liver failure cause

Last Updated: 2002-12-16 17:00:45 -0400 (Reuters Health)

By Merritt McKinney

NEW YORK (Reuters Health) - Overdoses of acetaminophen, the active

ingredient in Tylenol and other over-the-counter pain and fever relievers,

are now the leading cause of acute liver failure in the US, researchers

report.

But there is scant evidence that the recommended dose of acetaminophen can

harm the liver, according to the investigators. On average, people in the

study who went into acute liver failure were taking three times the maximum

daily dose of acetaminophen.

Unlike chronic liver failure, which develops gradually, acute liver failure

occurs when a person with no apparent liver disease suddenly experiences a

severe deterioration in liver function. Each year an estimated 2,000 people

in the US go into acute liver failure. During the past three decades, the

leading cause of acute liver failure has been hepatitis infection,

particularly hepatitis B.

That no longer seems to be the case, according to a study of 308 people who

experienced acute liver failure from 1998 through 2001 in the US.

" Drug-induced liver injury makes up more than 50% of cases, and viral

hepatitis appears on the decline as a cause of this acute liver function, "

the study's lead author, Dr. M. Lee of the University of Texas

Southwestern Medical Center in Dallas, told Reuters Health.

" More importantly, " Lee said, " acetaminophen constitutes nearly 40% of all

cases, and this appears to be increasing over the past two decades. "

Acetaminophen overdoses were responsible for 39% of the acute liver failure

cases in the study. Another 13% of cases were thought to be caused by the

effects of other medications. About 12% of cases stemmed from hepatitis A or

B infections, and another 17% were of uncertain cause. The findings are

published in Tuesday's edition of the journal ls of Internal Medicine.

The results of the study do not mean that acetaminophen, which is the most

popular over-the-counter pain reliever in the US, is unsafe. Eighty-three

percent of patients who went into liver failure after taking acetaminophen

had exceeded the maximum daily dose. Taking more than 4,000 milligrams per

day (4 g/d) of acetaminophen is not recommended.

According to Lee, acetaminophen overdose has been the leading cause of acute

liver failure in the UK, where it is known as paracetamol and is implicated

in 73% of cases of acute liver failure. " The study shows, Lee said, that " US

numbers are beginning to approach those in the UK. "

The difference between the US and the UK, however, Lee pointed out, is that

most acetaminophen overdoses are unintentional in the US. In the UK, cases

of acetaminophen overdose are " largely suicidal, " the Texas physician said.

According to the US Food and Drug Administration, common causes of

acetaminophen overdose include inadvertent use of multiple

acetaminophen-containing products at the same time and the misinformed

belief that larger doses will lead to faster relief.

One of the researchers received a Schering Research Fellowship from the

American Association for the Study of Liver Diseases.

SOURCE: ls of Internal Medicine 2002;137:947-954.