Time course of CYP3A activity during and after metamizole (dipyrone) in healthy volunteers.

Metamizole acts as a strong inducer of CYP3A already few days after start of metamizole administration and, thus, should be avoided in patients using drugs with narrow therapeutic index and major clearance via CYP3A. If their administration is essential, close monitoring and dose adjustment of co-medication should be performed as early as the first week after the initiation and after discontinuation of metamizole therapy.