Pirfenidone can increase hepatic enzyme levels, especially those of aspartate transaminase, alanine transaminase and gamma-glutamyl transpeptidase; periodic monitoring of hepatic enzyme levels is required during therapy: once before the initiation of therapy, monthly monitoring until 6 months after initiation of therapy, and 3 monthly thereafter. Extra precaution is required while prescribing the drug in patients with hepatic impairment and in patients who are concomitantly taking a CYP1A2 inhibitor. The drug is contraindicated in patients who have severe hepatic impairment.[1]