Disclosed is the use of pirfenidone for the manufacture of a medicament for treating a patient in need of pirfenidone therapy, wherein the treating comprises: (a) avoiding, contraindicating or discontinuing concomitant use or co-administration of a cytochrome P450 1A2 (CYP1A2) inhibitor that is a moderate to strong inhibitor of both (i) cytochrome P450 1A2 (CYP1A2) and (ii) another CYP enzyme selected from the group consisting of CYP2C9, CYP2C19, CYP2D6 and/or CYP2E1 in a patient receiving pirfenidone； (b) using with caution pirfenidone in a patient receiving a strong inhibitor of CYP1A2； (c) avoiding, contraindicating, discontinuing or using with caution a strong CYP1A2 inhibitor in a patient receiving pirfenidone； (d) avoiding, contraindicating, discontinuing or using with caution a CYP1A2 inhibitor selected from the group consisting of fluvoxamine, enoxacin, ciprofloxacin, amiodarone and propafenone in a patient receiving pirfenidone； or (e) reducing the dose of pirfenidone in patients receiving a strong inhibitor of CYP1A2.
