Acetaminophen (paracetamol) is used as an analgesic in many different
formulations. While therapeutic doses rarely cause adverse side effects, the effect
of long term treatment with acetaminophen is unclear. Cases have been reported
where chronic excessive use of acetaminophen has led to hepatotoxicity and
nephrotoxicity. In cases of acute overdosage, acetaminophen can cause severe
hepatic damage leading to hepatic failure if untreated.
The management of acetaminophen overdose requires early recognition of the drug in the bloodstream. Toxicity is generally reported at concentrations over 200 μg/mL(1324 μmol/L). N-acetylcysteine has been used as an antidote in conjunction with intensive support care. Early diagnosis of acetaminophen-induced hepatotoxicity is important since initiation of therapy within 8 hours of ingestion lessens the potential for hepatic injury and decreases the mortality rate.
The majority of methods for measuring acetaminophen are based on spectrophotometric or chromatographic principles. Chromatographic methods are specific for the parent compound; however, they are not well suited to emergency laboratories. Spectrophotometric methods are simpler and more rapid, but do not always offer the desired specificity.