Cytochrome P450 1A2 is the most important enzyme for hepatic metabolism of the metamizole metabolite 4-methylaminoantipyrine.

CYP1A2 is the major CYP for the conversion of 4-MAA to 4-AA and 4-FAA. The increase in 4-MAA exposure by the inhibition of CYP1A2 and by the combination CYP1A2/CYP2C19 may be relevant for dose-dependent adverse reactions of 4-MAA.