Drug Interactions of Pirfenidone

Pirfenidone is an oral antifibrotic medication primarily used for the treatment of idiopathic pulmonary fibrosis (IPF).

Drug Interactions of Pirfenidone

CYP1A2 Inhibitors

Concomitant use of pirfenidone with potent CYP1A2 inhibitors (e.g., fluvoxamine) is not recommended. CYP1A2 inhibitors increase the systemic exposure to pirfenidone. If discontinuation of CYP1A2 inhibitors is not feasible prior to initiating pirfenidone therapy, the dose of pirfenidone should be reduced. Monitor for adverse reactions and consider discontinuing pirfenidone if necessary.

Concomitant use of ciprofloxacin (a moderate CYP1A2 inhibitor, 750 mg twice daily) with pirfenidone is not recommended. If ciprofloxacin at this dose cannot be avoided, reduce the dose of pirfenidone and monitor the patient closely.

Concomitant use of medications that exert moderate or strong inhibitory effects on both CYP1A2 and other CYP isoenzymes involved in pirfenidone metabolism should be avoided during treatment.

CYP1A2 Inducers

Concomitant use of pirfenidone with potent CYP1A2 inducers should be avoided, as these inducers may reduce the exposure to and efficacy of pirfenidone.

Use of Pirfenidone in Specific Populations

Mild to Moderate Hepatic Impairment

Pirfenidone should be used with caution in patients with Child-Pugh Class A and B hepatic impairment. Monitor for adverse reactions and consider dose adjustment or discontinuation of pirfenidone as needed.

Severe Hepatic Impairment

Pirfenidone is not recommended for use in patients with Child-Pugh Class C hepatic impairment. No studies have been conducted in this patient population.

Renal Impairment (Mild, Moderate, Severe)

Pirfenidone should be used with caution in patients with mild (CLcr 50–80 mL/min), moderate (CLcr 30–50 mL/min), or severe (CLcr < 30 mL/min) renal impairment. Monitor for adverse reactions and consider dose adjustment or discontinuation of pirfenidone as needed.

End-Stage Renal Disease Requiring Dialysis

Pirfenidone is not recommended for use in patients with end-stage renal disease requiring dialysis. No studies have been conducted in this patient population.

Smokers

Smoking reduces the exposure to pirfenidone and may compromise its efficacy. Counsel patients to quit smoking prior to treatment and avoid smoking during pirfenidone administration.

Potential Serious Side Effects of Pirfenidone

Contact your healthcare provider immediately if the patient experiences any of the following serious side effects:

Liver Problems

Yellowing of the skin or whites of the eyes;

Dark or brown-colored urine (e.g., tea-colored);

Pain in the right upper abdomen;

Easy bleeding or bruising than usual;

Fatigue.

Liver function can be monitored via blood tests during pirfenidone treatment.

Photosensitivity and Rashes

Pirfenidone may make the skin more susceptible to sunburn.

Severe Cutaneous Adverse Reactions (SCAR)

Pirfenidone may trigger severe skin reactions, such as skin blisters, rashes, oral ulcers, urticaria, or other serious skin manifestations.

Gastrointestinal Issues

Pirfenidone may cause nausea, vomiting, diarrhea, dyspepsia, heartburn, and abdominal pain.