NSAIDs are commonly used over-the-counter medications that can cause drug-induced liver injury (DILI), as highlighted in a case report of a 64-year-old man, published in the Annals of Internal Medicine: Clinical Cases.

The patient was admitted complaining of severe discomfort in the upper right side of his abdomen. His medical history revealed issues with alcohol consumption, an operation to remove his gallbladder three months prior due to cholecystolithiasis and a colostomy resulting from an abdominal gunshot wound. According to the patient, he had not consumed any alcohol for over a year, had not recently travelled and had not been taking any illicit drugs.

The patient had been taking ibuprofen 600 mg 4 times a day for 2 weeks, methocarbamol 750 mg 4 times a day for 1 week and hydrocodone 5 mg/acetaminophen 325 mg twice a day for prolonged shoulder pain.

A blood test showed elevated liver enzymes, while other test results were within normal range. Investigations for acute liver failure and viral serologies were negative. However, a urine toxicology test was positive for opiates, and the patient's ultrasound and CT scan showed signs of liver injury. During his hospitalisation, the patient experienced a decrease in abdominal pain and liver enzyme levels. His aspartate transaminase level dropped to 597 U/L, alanine aminotransferase level dropped to 163 U/L and alkaline phosphatase level remained at 198 U/L. Based on diagnostic results and clinical presentation, the authors concluded that the patient was most likely suffering from DILI caused by ibuprofen. His condition improved after discontinuing the medication.

The mechanism behind ibuprofen and other NSAID-related liver injury is still unclear. One hypothesis suggests that the cause is immune-mediated, as NSAID-related DILI did not seem to be dose-dependent, and ibuprofen overdose was found rarely to cause toxic liver damage. However, another hypothesis suggests that liver damage results from an accumulation of plasma concentrations of NSAIDs and their toxic metabolites. Ibuprofen is metabolised by cytochrome P450 enzymes and UDP-glucuronosyltransferases and genetic polymorphisms involving these enzymes have been shown to be more common in individuals who have developed diclofenac-related liver injury. Hepatitis B and C, non-alcoholic fatty liver disease and environmental factors such as diet, older age and female sex can increase the risk of DILI.

This article was translated from Univadis Germany.

Over-the-counter medications can cause serious liver injury

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