pirfenidon

Pirfenidon, more commonly spelled pirfenidone in English-language sources, is an antifibrotic medication used to treat fibrosing lung diseases. It is approved in many countries for idiopathic pulmonary fibrosis (IPF) in adults and has been studied for other progressive fibrosing interstitial lung diseases.

Mechanism of action is not fully understood, but pirfenidone exhibits anti-fibrotic and anti-inflammatory effects. It is thought to inhibit profibrotic cytokines such as transforming growth factor-beta (TGF-β), reduce fibroblast proliferation and myofibroblast differentiation, and decrease collagen synthesis, thereby slowing the progression of fibrosis.

Administration and dosing are oral. The drug is typically taken with meals to improve tolerability, with a titration period over about two weeks to reach the target daily dose. Dosing may be adjusted based on tolerability and liver function.

In clinical use, pirfenidone has been shown to slow the decline in lung function in IPF and is part of a comprehensive management approach for eligible patients. It may also be studied or used off-label in other progressive fibrosing interstitial lung diseases, depending on regional guidelines and approvals.

Adverse effects and safety considerations include nausea, dyspepsia, fatigue, rash, photosensitivity, and elevations in liver enzymes. Liver function tests should be monitored regularly due to potential hepatotoxicity. Pirfenidone is metabolized in the liver, primarily via CYP1A2, and may interact with other medicines that affect this enzyme. It is cautionary in pregnancy and used with care in patients with liver impairment.

Availability varies by country; a brand-name version known as Esbriet exists, with generic versions available in some regions.