Is There an Increased Risk of Hepatotoxicity with Metamizole? A Comparative Cohort Study in Incident Users

Across the Border: A Metamizole Drug-Induced Liver Injury

Metamizole (dipyrone) is a medication with analgesic, antipyretic, and spasmolytic properties, widely used in Mexico and other Latin American countries. It is often grouped with non-steroidal anti-inflammatory drugs (NSAIDs) due to its pain-relieving and fever-reducing effects, making it a common over-the-counter option. However, concerns over its potential to cause agranulocytosis led to its removal from the U.S. market. Reports of drug-induced liver injury (DILI) related to metamizole are uncommon but noteworthy. Given its frequent use in Latin America and parts of Europe, awareness of this possible adverse effect is important. A 39-year-old man with no prior medical conditions sought medical care for persistent right upper quadrant pain and jaundice lasting two weeks. To address his symptoms, he had been prescribed a compounded medication containing butylscopolamine and metamizole in Ciudad Juárez, Mexico. Shortly after, he noticed yellowing of his skin and eyes, prompting him to seek care in the United States. Laboratory findings indicated a mixed hepatocellular pattern of liver injury (total bilirubin: 6.5, direct bilirubin: 5.1, aspartate aminotransferase: 1,496, alkaline phosphatase: 130, and alanine aminotransferase: 2,579). Additional testing showed elevated transferrin saturation and ferritin levels (82%; 57,700). Imaging of the abdomen revealed periportal edema without other significant abnormalities. A thorough evaluation for viral, autoimmune, and genetic liver diseases yielded negative results. A liver biopsy demonstrated features of portal and lobular hepatitis with eosinophilic infiltration, suggesting DILI. Prussian blue staining did not indicate iron accumulation. Given the timing and exclusion of other causes, the reaction was attributed to the metamizole-containing medication. Discontinuation of the drug and supportive care led to biochemical improvement and resolution of jaundice. Metamizole-related DILI may be underrecognized, particularly in regions where the drug is no longer available. However, it remains widely used in Latin America, relevant for clinicians treating immigrant populations. Recognizing international medication use and obtaining a thorough drug history is essential, especially when managing patients exposed to pharmaceuticals not routinely encountered in the United States.

Effects of Metamizole, 4-Methylaminoantipyrine, and 4-Aminoantipyrine on LX-2 Liver Cell Line Viability and Apoptosis

Metamizole (dipyrone) is a non-opioid analgesic widely used in human and veterinary medicine, despite ongoing concerns about its safety due to risks such as agranulocytosis and potential hepatotoxicity. This study investigates the cytotoxic (MTT assay) and pro-apoptotic effects of metamizole and its primary metabolites, 4-methylaminoantipyrine (4-MAA) and 4-aminoantipyrine (4-AA), on the LX-2 liver cell line. These metabolites are implicated in both the therapeutic and adverse effects of the drug. The objective is to elucidate the mechanisms of potential hepatotoxicity, with a focus on cell viability and apoptosis. Metamizole was tested at five concentrations (100, 200, 400, 600, and 1000 µg/mL), while its metabolites were tested at two concentrations (100 and 1000 µg/mL). The results show a dose-dependent decrease in cell viability, with significant reductions at higher concentrations. The greatest cytotoxic effects were observed with 4-AA and 4-MAA, which induced marked apoptosis at 1000 µg/mL. This study concludes that metamizole and its metabolites can cause liver cell damage, underscoring the importance of caution in its clinical use and the need for further research to ensure its safety.

Adverse effects of metamizole on heart, lung, liver, kidney, and stomach in rats

BACKGROUND

Metamizole is banned in some countries because of its toxicity, although it is widely used in some European countries. In addition, there is limited information on its safety profile, and it is still debated whether it is toxic to the heart, lungs, liver, kidneys, and stomach.

AIMS

Our study investigated the effects of metamizole on the heart, lung, liver, kidney, and stomach tissues of rats.

METHODS

Eighteen rats were divided into three groups, wassix healthy (HG), 500 mg/kg metamizole (MT-500), and 1000 mg/kg metamizole (MT-1000). Metamizole was administered orally twice daily for 14 days. Meanwhile, the HG group received pure water orally. Biochemical, histopathologic, and macroscopic examinations were performed on blood samples and tissues.

RESULTS

Malondialdehyde (MDA), total glutathione (tGSH), superoxide dismutase (SOD), and catalase (CAT) in the lung and gastric tissues of MT-500 and MT-1000 groups were almost the same as those of the HG (p > 0.05). However, MDA levels in the heart and liver tissues of MT-500 and MT-1000 groups were higher (p < 0.05) compared to the HG, while tGSH levels and SOD, and CAT activities were lower (p < 0.05). MDA levels of MT-500 and MT-1000 groups in the kidney tissue increased the most (p < 0.001), and tGSH levels and SOD and CAT activities decreased the most (p < 0.001) compared to HG. Metamizole did not cause oxidative damage in the lung and gastric tissue. While metamizole did not change troponin levels, it significantly increased alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), and creatinine levels compared to HG. Histopathologically, mild damage was detected in heart tissue, moderate damage in liver tissue, and severe damage in renal tissue. However, no histopathologic damage was found in any groups' lung and gastric tissues.

CONCLUSION

Metamizole should be used under strict control in patients with cardiac and liver diseases and it would be more appropriate not to use it in patients with renal disease.