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A MOUTHFUL OF DEATH: ACETAMINOPHEN OVERDOSE

by Theodore J. Powell,  RN, MSN, Ph.D.

You have just received the report on an overdose patient who will be coming from the Emergency Department to your floor. Sixteen-year-old Amanda had an argument with her mother and tried to commit suicide by taking a Amouthful of acetaminophen. About two hours after taking the medication Amanda got scared and informed her mother of what she had done.

Upon arrival in the Emergency Department, approximately three hours after her overdose, Amanda was immediately started on treatments to help prevent liver damage that could lead to her death. In this article you will learn about acetaminophen and how it can damage the liver, tests performed when there is an acetaminophen overdose, treatments commonly used in an acetaminophen overdose and the supportive care of an acetaminophen overdose patient.

Also known by its chemical name, N -acetyl-p -aminophenol or APAP, acetaminophen became an over-the-counter medication in the 1950's. An analgesic-antipyretic, acetaminophen is available as a single drug or in combination with other common prescription and over-the-counter medications such as Lortab™, Anacin™ and Midol™. Acetaminophen is
available under the brand name Tylenol™ and other trade or generic names. The brand name Tylenol™ is derived from it's chemical name N -acetyl-p -aminophenol. Although acetaminophen is exceptionally safe when taken in therapeutic doses, liver damage can occur by taking more than the recommended dose or when taken with other substances such as alcohol.

In the United States, attempted suicide accounts for more than two thirds of acetaminophen-related liver injuries, whereas accidental overdoses account for only one third of the cases.1

The liver accomplishes many important functions such as storing glycogen, regulating blood glucose, plasma protein synthesis, hormone production, removing waste products from your blood and breaking down (metabolizing) and eliminating toxins. When you eat, the liver
absorbs and stores fat, sugars, vitamins and other nutrients that you have consumed. When acetaminophen is taken into the body, the liver metabolizes it into the chemical N -acetyl-benzoquinoneimine (NAPQI). Although acetaminophen itself is nontoxic to the liver, the metabolite NAPQI can destroy liver cells (hepatocytes).

The liver metabolizes approximately 90 percent of the absorbed acetaminophen dose into water soluble sulfate and glucuronide conjugates.2 These conjugates are then removed from the blood
stream by the kidneys and eliminated from the body. Most of the remaining acetaminophen binds to glutathione and is then excreted as nontoxic mercapturate conjugates. Glutathione, which is manufactured inside the cell, is often called the body's master detoxifier. Consuming
foods rich in sulphur-containing amino acids, such as asparagus, garlic and avocado, can help increase liver glutathione levels. The drug N-acetylcysteine (NAC) or acetylcysteine, commonly known by the brand name Mucomyst™, is quickly metabolized into glutathione once it enters the body.

In an acetaminophen overdose the stores of glutathione are used up and NAPQI is not detoxified. The NAPQI which is not detoxified can then bond to the lipid bilayer of hepatocytes causing them to become necrotic. In addition to NAPQI using up the stores of glutatione in the body,
other factors can affect the amount of glutatione available. Malnutrition, chronic alcoholism, age and diet can lower the body's glutatione stores. Alcohol (ethanol) and other substances or drugs can increase the production of NAPQI thus increasing the possibility of hepatic injury.

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