Evaluation of drug-drug interactions associated with metamizole in clinical practice

BACKGROUND: Metamizole, a non-steroidal anti-inflammatory drug and moderate inducer of cytochrome P450 enzymes (CYP3A4, CYP2B6, CYP2C19), has gained increased use in clinical practice. This retrospective study evaluates the number of drug-drug interactions (DDIs) associated with metamizole when prescribed for ≥24 h. RESEARCH DESIGN AND METHODS: Data were collected from the electronic healthcare records of adult patients prescribed metamizole at Tergooi Medical Center between June 2017 and May 2024. Relevant DDIs with metamizole were identified using the Metamizole DDI Manager developed by Global DDI Solutions. Only clinically relevant, i.e. orange (action may be needed) and red (contra-indicated), DDIs that occurred during or within seven after discontinuation of metamizole treatment in a hospital setting were considered. RESULTS: A total of 37,110 unique patients received at least one metamizole prescription of which 2.6% (n = 968) were treated for ≥24 h. Of these, 98.6% (n = 954) were prescribed at least one interacting medication. In total, 3680 DDIs were identified, corresponding to an average of 3.8 DDIs per metamizole prescription. Of the 98 interacting medications identified, 95% were classified as orange, and 5% as red. CONCLUSIONS: In conclusion, metamizole is associated with a many DDIs in clinical practice. This highlights the need for careful monitoring when prescribed.