Pirfenidone is an orally administered antifibrotic agent, specifically indicated for the treatment of mild to moderate Idiopathic Pulmonary Fibrosis (IPF). It is a pyridone derivative that modulates multiple pathways involved in fibrosis, including TGF-β and TNF-α. In the Indian context, it is a critical therapy for slowing disease progression in IPF, a condition with limited treatment options and poor prognosis.
Adult: The maintenance dose is 801 mg (one 267 mg capsule three times daily) or 600 mg tablet three times daily, totaling 2403 mg/day. Dose titration is mandatory: Week 1-7: 267 mg three times daily (801 mg/day). Week 8-14: 534 mg three times daily (1602 mg/day). Week 15 onward: 801 mg three times daily (2403 mg/day). For the 600mg tablet formulation: 1 tablet three times daily (1800 mg/day) after titration.
Note: Administer WITH FOOD to reduce nausea and dizziness and to increase bioavailability. Tablets/Capsules should be swallowed whole with a full glass of water. Do not crush or chew. Doses should be taken at the same times each day, approximately 8 hours apart.
Pirfenidone's exact mechanism in IPF is not fully elucidated but is believed to involve the downregulation of key profibrotic and pro-inflammatory cytokines. It inhibits the synthesis of TGF-β (Transforming Growth Factor-beta), a central mediator of fibrosis, and TNF-α (Tumor Necrosis Factor-alpha), a key cytokine in the inflammatory cascade. It also reduces the production of PDGF (Platelet-Derived Growth Factor) and inhibits collagen synthesis, fibroblast proliferation, and extracellular matrix deposition.
Pregnancy: Category C (US FDA). Animal studies have shown fetal toxicity (reduced fetal weight, delayed ossification). There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus.
Driving: Pirfenidone may cause dizziness and fatigue. Patients should be cautioned about operating machinery or driving until they know how the medication affects them.
| Fluvoxamine (strong CYP1A2 inhibitor) | Markedly increases pirfenidone exposure (AUC increased by ~80%). Risk of toxicity. | Major - Avoid combination. |
| Ciprofloxacin (moderate CYP1A2 inhibitor) | Increases pirfenidone exposure. Consider dose reduction or increased monitoring. | Moderate |
| Omeprazole, Smoking (CYP1A2 inducers) | Decreases pirfenidone exposure, potentially reducing efficacy. | Moderate |
| Other photosensitizing drugs (e.g., Doxycycline, Fluoroquinolones, Thiazides) | Increased risk of severe photosensitivity reactions. | Moderate |
| Alcohol | May exacerbate dizziness and gastrointestinal side effects. | Minor |
Same composition (Pirfenidone (600mg)), different brands: