In the presence of ketoconazole 400 mg once daily, a strong CYP3A4 inhibitor,
exposure to macitentan increased approximately 2-fold. The predicted increase was approximately 3-
fold in the presence of ketoconazole 200 mg twice daily using physiologically based pharmacokinetic
(PBPK) modelling. The uncertainties of such modelling should be considered. Exposure to the active
metabolite of macitentan was reduced by 26%. Caution should be exercised when macitentan is
administered concomitantly with strong CYP3A4 inhibitors