Best tolerated dose of Pirfenidone in patients with idiopathic pulmonary fibrosis

Background: It was observed that not all patients having idiopathic pulmonary fibrosis (IPF) and were tolerating the full recommended dose of pirfenidone 2400 mg/day. Aims: Examine the best tolerated dose of pirfenidone administered to patients with IPF and the adverse effects leading to a dose reduction. Methods: 87 Patients (M:F, 51:36) were included. Pirfenidone was initiated at 600 mg per day, administered with food and escalated every 1 to 2 weeks with monitoring of liver function test and adverse events to target 2400 mg/day. If the escalated dose was not tolerated then the previous best tolerated dose was continued. Since the availability to Nintedanib, the switch option was given to patients not tolerating recommended dose of Pirfenidone. In our setting treatment cost is borne by patient. Pirfenidone is typically our first choice antifibrotic for IPF as it is generic and cheaper compared to nintedanib. Results: 74/87 (85%) patients had IPF–UIP, 4 CPFE and in 9 patients pirfenidone was administered off label for advanced fibrosing interstitial lung diseases (2 RA – UIP, 4 chronic hypersensitivity pneumonitis, 3 post H1N1 lung fibrosis). Mean duration of follow up was 515 + 588 days. 1 patient tolerated 600 mg/day, 39 (45%) patients 1200 mg/day, 29 (33%) patients 1800 mg/ day and 18 (21%) 2400 mg/day. Major adverse events limiting the dose of pirfenidone were gastoinstestinal side effects(33), deranged liver enzymes(7), weight loss(19), itching(7), dizziness(3). 6 patients switched to nintedanib. Conclusion: Most patients with IPF do not tolerate the full recommended dose of pirfenidone at 2400mg/day. Gastrointestinal side effects and weight loss are the most common cause of dose limitation.