Acetaminophen can be purchased in regular strength, extra strength, extended-release form, arthritis formula and in several pediatric strengths. It is available in liquid and chewable forms, and in tablets. Both the extended-release and arthritis formula tablets have an outer layer that dissolves immediately, then the remaining medication dissolves slowly allowing pain relief for up to eight hours. The extended-release form of acetaminophen should be swallowed whole, not chewed.

The recommended dose of regular acetaminophen for adults and children 12 years of age or older is up to 650 milligrams every four to six hours. The recommended dose of extra-strength acetaminophen is up to 1000 milligrams every four to six hours. Extended-release acetaminophen has a recommended dose of 1300 milligrams every eight hours. For children less than 12 years of age and/or less than 50 kilograms in weight the recommended dose of acetaminophen is 10 to 15 milligrams per kilogram of the child's body weight every four to six hours. Acetaminophen extended-release, extra strength and arthritis formulas are not recommended for children less than 12 years of age. Quickly absorbed from the upper
gastrointestinal tract, acetaminophen peak plasma levels occur between 30 and 60 minutes when a therapeutic dose is taken. When an overdose is consumed, the peak plasma level usually occurs within four hours. In adults, a single dose of 12 grams (24 extra-strength tablets) and in
children less than 12 years of age a single dose of 250 milligrams per kilogram, can cause liver toxicity. A person who takes a fatal dose of acetaminophen may seem well for a day or two before the signs and symptoms of hepatic or kidney failure become apparent.

Although Amanda said that she had taken a A "mouthful" of pills, and her mother brought a half-empty acetaminophen extra-strength bottle, the reported history of how much acetaminophen was ingested is often inaccurate and is not a reliable guide to therapy. Obtaining a blood serum concentration of acetaminophen is the only way to correctly assess the risk of hepatotoxicity.

As stated earlier, peak plasma levels in an overdose occur approximately four hours after ingestion. The emergency department physician may order blood tests upon Amanda's arrival, but will usually wait four hours after the acetaminophen ingestion before ordering a serum acetaminophen concentration. Treatment, however, is started immediately upon
Amanda's arrival to the hospital.

Treatment for an acetaminophen overdose can vary depending on the physician and on hospital policy. The first step would be to empty the patient's stomach by lavage or by inducing emesis with syrup of ipecac. Then activated charcoal may be administered, followed by oral or intravenous doses of acetylcysteine. However, oral acetylcysteine is absorbed by activated charcoal thereby decreasing its effectiveness. If activated charcoal treatment is given, the patient will need to be lavaged prior to the administration of oral acetylcysteine. Although the United States Federal Drug Administration has approved the administration of acetylcysteine intravenously, many doctors in the United States still prefer using the oral preparation. Dialysis has not been found to be an effective treatment for acetaminophen overdoses.

Acetylcysteine should be administered immediately if the acetaminophen ingestion occurred within 24 hours or less, and must be started within 10 hours to protect against severe liver damage. When the result of the acetaminophen plasma concentration is available, the physician
can refer to an acetaminophen toxicity nomogram (Rumack-Matthew nomogram)3 to determine if acetaminophen plasma concentrations are in the toxic range and if maintenance doses of acetylcysteine are needed. Acetylcysteine 20% solution is available in 4, 10 or 30-milliliter rubber-stoppered glass vials. The recommended loading dose of acetylcysteine is 140 mg per kg of body weight and the recommended maintenance doses are 70 mg per kg of body weight every four hours for a total of 18 doses (including the loading dose). If the patient vomits the oral loading or maintenance doses within one hour of administration, the dose should be repeated. Before giving oral doses of acetylcysteine you must dilute the 20% solution to a 5% concentration with cola drinks, other soft drinks, or juice. If the patient is unable to retain orally administered acetylcysteine, the doses may be diluted with sterile water and administered by duodenal intubation. Antiemetics such as Reglan™ and Zofran™ may be used if the patient becomes nauseated.

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