Pirfenex is an antifibrotic agent specifically indicated for the treatment of idiopathic pulmonary fibrosis (IPF). It works by inhibiting the processes that lead to fibrosis and scarring of lung tissue. This medication is designed to slow the decline in lung function, offering a targeted therapeutic approach for a condition with limited treatment options. Clinical evidence supports its role in preserving vital capacity and reducing the risk of acute exacerbations in eligible patients.

Features

• Contains the active pharmaceutical ingredient Pirfenidone
• Available in 200 mg and 600 mg film-coated tablets
• Prescription-only medication requiring specialist initiation
• Manufactured under strict pharmaceutical Good Manufacturing Practice (GMP) standards
• Specific storage requirements to maintain stability

Benefits

• Slows the rate of decline in forced vital capacity (FVC)
• Reduces the risk of disease progression and mortality in IPF
• May decrease the frequency of acute exacerbations
• Helps preserve exercise tolerance and functional capacity
• Offers a well-characterized safety profile from extensive clinical trials
• Provides a targeted mechanism against key pathways in fibrosis development

Common use

Pirfenex is exclusively approved for the treatment of idiopathic pulmonary fibrosis, a chronic, progressive, and ultimately fatal interstitial lung disease of unknown cause characterized by progressive scarring of lung parenchyma. It is used in adult patients to modify disease progression rather than provide symptomatic relief. Diagnosis must be established through appropriate diagnostic workup including high-resolution computed tomography (HRCT) when necessary, following international guidelines. Treatment is typically initiated and monitored by pulmonologists or physicians specializing in interstitial lung diseases.

Dosage and direction

The recommended maintenance dosage is 801 mg three times daily (2403 mg/day), taken with food to minimize gastrointestinal adverse reactions. Initiate treatment with a titration schedule over 14 days to reach the full maintenance dose:

Days 1-7: 267 mg (one 267 mg capsule) three times daily (801 mg/day) Days 8-14: 534 mg (two 267 mg capsules) three times daily (1602 mg/day) Day 15 onward: 801 mg (three 267 mg capsules) three times daily (2403 mg/day)

Tablets should be swallowed whole with adequate fluid. Do not crush, chew, or break tablets due to the bitter taste and potential impact on drug release. Regular assessment of liver function tests is required before and during treatment.

Precautions

Liver function monitoring is essential: obtain ALT, AST, and bilirubin levels before treatment initiation, monthly for the first 6 months, and every 3 months thereafter. Photosensitivity reactions are common; patients should avoid direct sunlight, use sunblock (SPF 50 or higher), and wear protective clothing. Use with caution in patients with mild to moderate hepatic impairment (Child-Pugh Class A and B); contraindicated in severe hepatic impairment. Exercise caution in patients with end-stage renal disease (CLcr <30 mL/min) requiring dialysis. Smoking may reduce Pirfenidone exposure; patients should be advised to stop smoking. Regular monitoring of weight and clinical status is recommended.

Contraindications

Hypersensitivity to pirfenidone or any excipients in the formulation. Severe hepatic impairment (Child-Pugh Class C). Concomitant use with fluvoxamine or other strong CYP1A2 inhibitors. History of angioedema with pirfenidone use. Moderate to severe hepatic impairment without appropriate monitoring capabilities. Pregnancy and breastfeeding unless potential benefit justifies potential risk to fetus or infant.

Possible side effects

The most common adverse reactions (occurring in >10% of patients) include:

• Nausea (36%)
• Rash (30%)
• Abdominal pain (24%)
• Upper respiratory tract infection (27%)
• Diarrhea (26%)
• Fatigue (26%)
• Headache (22%)
• Dyspepsia (19%)
• Photosensitivity reaction (12%)
• Dizziness (18%)

Serious but less common adverse reactions include:

• Liver enzyme elevations (ALT/AST >3x ULN in 3.7% of patients)
• Significant photosensitivity reactions requiring medical intervention
• Gastrointestinal disorders leading to treatment discontinuation
• Angioedema (rare but serious)

Drug interaction

Pirfenidone is primarily metabolized by CYP1A2 with minor contributions from other CYP isoenzymes. Significant interactions include:

• Strong CYP1A2 inhibitors (fluvoxamine, enoxacin): Contraindicated due to increased pirfenidone exposure
• Moderate CYP1A2 inhibitors (ciprofloxacin, amiodarone): Reduce pirfenidone dose
• CYP1A2 inducers (smoking, omeprazole): May decrease pirfenidone efficacy
• Drugs that cause photosensitivity (tetracyclines, fluoroquinolones): Additive photosensitivity risk
• Other antifibrotic agents: No clinical data on combination therapy

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is less than 3 hours until the next scheduled dose. In that case, skip the missed dose and resume the regular dosing schedule. Do not double the dose to make up for a missed dose. If multiple doses are missed, contact the prescribing physician for guidance on retitration.

Overdose

There is limited experience with pirfenidone overdose. Reported cases involved doses up to 4005 mg (five times the recommended daily dose) with symptoms including dizziness, nausea, and fatigue. In case of suspected overdose, provide symptomatic and supportive care. There is no specific antidote. Hemodialysis may be considered as pirfenidone has approximately 50% renal excretion, though its effectiveness has not been established. Monitor liver function tests and provide appropriate gastrointestinal symptom management.

Storage

Store at room temperature (20-25°C or 68-77°F) with excursions permitted between 15-30°C (59-86°F). Keep in the original container with the lid tightly closed to protect from moisture and light. Do not remove desiccant from the bottle. Keep out of reach of children and pets. Do not use after the expiration date printed on the packaging. Do not transfer to other containers as this may affect stability.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Pirfenex is a prescription medication that should only be used under the supervision of a qualified healthcare professional. The prescribing physician should be consulted for complete information regarding indications, contraindications, warnings, precautions, and adverse reactions. Individual patient response may vary. Always follow the guidance of your healthcare provider regarding medication use.

Reviews

Clinical trials demonstrate that pirfenidone significantly reduces decline in forced vital capacity compared to placebo. In the ASCEND trial (n=555), pirfenidone reduced the proportion of patients with a ≥10% decline in FVC or death by 47.9% at 52 weeks. The CAPACITY trials showed similar results, with a 30% reduction in FVC decline in one study. Real-world evidence supports these findings, with patients typically experiencing stabilization of lung function decline. Most specialists report that patients who tolerate the medication well show meaningful slowing of disease progression. Common challenges include gastrointestinal side effects during titration, though these often improve with time and management strategies.