Drug-Induced Liver Injury Caused by Metamizole: Identification of a Characteristic Injury Pattern

Area of Science:

• Hepatology
• Pharmacovigilance
• Clinical Toxicology

Background:

• Drug-induced liver injury (DILI) from metamizole is a growing concern.
• Assessing causality is challenging, particularly with multiple medications.
• This study aimed to further characterize metamizole-induced DILI cases.

Purpose of the Study:

• To characterize the clinical presentation of metamizole-induced DILI.
• To identify predictors of fatal outcomes in metamizole DILI.
• To compare metamizole DILI with other forms of DILI and autoimmune hepatitis.

Main Methods:

• Analysis of data from a prospective study on drug-related acute liver injury.
• Inclusion of patients with documented metamizole intake.
• Diagnosis and causality assessment based on thorough work-up and long-term follow-up.

Main Results:

• Metamizole was associated with DILI in 18.8% of cases.
• A characteristic pattern of elevated transaminases and bilirubin was observed in 43/61 patients.
• International Normalized Ratio (INR) at onset demonstrated high accuracy (c-statistic 0.85) in predicting fatal outcomes, outperforming Hy's law and MELD score.

Conclusions:

• Metamizole DILI exhibits a recognizable clinical pattern useful for identifying the causative agent.
• Fatal outcomes in metamizole DILI are not predicted by the characteristic clinical picture.
• INR at the onset of DILI is a strong independent predictor of fatal adverse outcomes.