[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antifibrotics](https://durgical.com/en/pharmacology/classes/antifibrotics/) › Pirfenidone # Pirfenidone ## Antifibrotics? Antifibrotics An oral antifibrotic for idiopathic pulmonary fibrosis; taken with food, it causes nausea, rash and sun sensitivity and needs liver tests. Updated Nov 1, 2026 ## Quick facts **Group** [Antifibrotics](https://durgical.com/en/pharmacology/classes/antifibrotics/) **Target** Fibrogenic and inflammatory signalling in lung fibroblasts (molecular target not established) **Used for** Idiopathic pulmonary fibrosis **Key effects** Nausea · Rash and photosensitivity · Fatigue **Monitor** Liver tests · Skin · Nausea **ATC** L04AX05 No doses: the clinician sets them by the current guideline. On this page - The basics Mechanism of action - Indications - Adverse effects - Pharmacokinetics - Memory aid - Safety Contraindications - Key interactions - What is monitored - Administration and safety - Pregnancy and breastfeeding - Nursing care - Study Test yourself - Connections Connections ## Mechanism of action Pirfenidone is a pyridone with antifibrotic and anti-inflammatory effects in experimental models: it reduces fibroblast proliferation and the growth factors and collagen production that drive fibrosis. How it works in patients with idiopathic pulmonary fibrosis has not been established. In trials it slowed the decline in forced vital capacity. - Lung injury drives fibroblasts to proliferate and make collagen - Pirfenidone dampens fibrogenic growth-factor signalling - Fibroblasts proliferate less and deposit less collagen - The decline in lung function slows ## Indications - Idiopathic pulmonary fibrosis [Interstitial lung disease →](https://durgical.com/en/conditions/interstitial-lung-disease/) ## Adverse effects ### Common - Nausea, dyspepsia, reflux, vomiting and abdominal pain - Rash and photosensitivity - Fatigue, dizziness and headache - Decreased appetite and weight loss - Upper respiratory infections, sinusitis and insomnia ### Serious (rare, important) - Drug-induced liver injury, including fatal cases - Severe skin reactions: Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS - Severe photosensitivity reactions ## Contraindications - No absolute contraindications on the label - Use with fluvoxamine is avoided - Hypersensitivity to pirfenidone ## Key interactions **Fluvoxamine (strong CYP1A2 inhibitor)** Much higher pirfenidone exposure; avoided **Ciprofloxacin (moderate CYP1A2 inhibitor)** Higher exposure; the pirfenidone dose is reduced **Smoking and strong CYP1A2 inducers** Lower exposure and possible loss of effect ## What is monitored - Liver tests (ALT, AST, bilirubin) before starting, monthly for the first six months and then every three months - Skin: rash, blistering or sunburn-like reactions - Nausea, appetite and weight ## Administration and safety - Oral capsules or tablets taken with food, at the same times each day - The dose is built up gradually at the start; if treatment is interrupted for a long time it is restarted with the build-up - Avoid sun and sunlamps: sunscreen and protective clothing ## Pregnancy and breastfeeding Human data are insufficient; animal studies did not show malformations, and use is weighed with the specialist. ## Nursing care - Teach sun protection every day, even on cloudy days - Check liver tests and teach the signs of liver injury - Teach to take each dose with food to lessen nausea and dizziness - Advise stopping smoking, which also lowers drug levels - Review the medicine list for fluvoxamine and ciprofloxacin ## Pharmacokinetics **Absorption** Oral; food delays absorption and lowers the peak level, which improves tolerance **Distribution** Moderately bound to plasma proteins, mainly albumin **Metabolism** Liver, mainly by CYP1A2 (minor CYP2C9, 2C19, 2D6, 2E1); smoking induces CYP1A2 and lowers exposure **Elimination** Mostly in urine as the inactive 5-carboxy metabolite **Half-life** About 3 hours ## Memory aid PIRFenidone needs a hat and a plate: sun protection (photosensitivity) and food with every dose (nausea). ## Test yourself Think of the answer, then tap the question to see it. ## Which CYP enzyme mainly metabolises pirfenidone? CYP1A2. ## Why does smoking matter in a patient on pirfenidone? Smoking induces CYP1A2, lowers pirfenidone exposure and may reduce its effect. ## Which skin precaution is taught to every patient on pirfenidone? Avoid sun and sunlamps, and use sunscreen and protective clothing (photosensitivity). [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/pirfenidone/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## Connections ## Related drugs 2 - [Nintedanib](https://durgical.com/en/pharmacology/nintedanib/) - [Ciprofloxacin](https://durgical.com/en/pharmacology/ciprofloxacin/) ## Related conditions 1 - [Interstitial lung disease](https://durgical.com/en/conditions/interstitial-lung-disease/) [← Back to the class: Antifibrotics](https://durgical.com/en/pharmacology/classes/antifibrotics/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [DailyMed - PIRFENIDONE- pirfenidone tablet, film coated](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1abc06c7-6a45-4a0b-b2da-c228aaa137ed) (DailyMed (U.S. National Library of Medicine), 2025); [Pirfenidone: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a615008.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L04AX05) (WHO Collaborating Centre for Drug Statistics Methodology, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/pirfenidone/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/pirfenidone/