Drug Interaction Report

GENERALLY AVOID: The concurrent use of fezolinetant with systemic estrogen hormone replacement therapy has not been evaluated in prospective clinical trials. Safety and efficacy of this combination are unknown. However, the concomitant use of vaginal estrogen preparations was excluded from this warning in the product labeling for Australia and the United Kingdom.

MANAGEMENT: Due to the lack of clinical data, use of fezolinetant with systemic estrogen-containing hormone replacement therapy is not recommended. Vaginal estrogen preparations may be used according to some authorities.

CONTRAINDICATED: Coadministration with inhibitors of CYP450 1A2 such as caffeine may significantly increase the plasma concentrations of fezolinetant, which is primarily metabolized by the isoenzyme. The interaction has not been studied with caffeine but has been reported for other CYP450 1A2 inhibitors. Consumption of caffeine-containing food or beverages (e.g., chocolate, coffee, cola drinks, energy drinks, tea) could result in an interaction with fezolinetant. In clinical drug interaction studies, coadministration of the potent CYP450 1A2 inhibitor fluvoxamine increased the peak plasma concentration (Cmax) and systemic exposure (AUC) by 80% and 840%, respectively. Likewise, the moderate CYP450 1A2 inhibitor, mexiletine, is predicted through physiologically based pharmacokinetic (PBPK) modeling to increase the Cmax and AUC of fezolinetant by 40% and 360%, respectively. The weak CYP450 1A2 inhibitor cimetidine is also predicted via PBPK to increase the Cmax and AUC of fezolinetant by 30% and 100%, respectively.

MANAGEMENT: Concomitant use of fezolinetant with CYP450 1A2 inhibitors such as caffeine, including caffeine-containing food or beverages, is considered contraindicated.