idiopathic%20pulmonary%20fibrosis
IDIOPATHIC PULMONARY FIBROSIS

Idiopathic pulmonary fibrosis is the progressive parenchymal scarring & loss of pulmonary function due to unidentifiable cause of lung injury.

It is a specific form of chronic fibrosing interstitial pneumonia with the histopathologic characteristics of usual interstitial pneumonia.

Approximately 5% of patients are asymptomatic. Common signs and symptoms are exertional dyspnea, nonproductive cough, finger clubbing and bilateral inspiratory crackles.

Pharmacotherapy

Nintedanib

  • A receptor blocker for multiple kinases
  • Mediates the elaboration of fibrogenic growth factors:
    • Vascular endothelial growth factor receptors (VEGFR) 1-3
    • Fibroblast growth factor receptors (FGFR) 1-3
    • Platelet-derived growth factor receptors (PDGFR) 
  • Its efficacy in idiopathic pulmonary fibrosis were evaluated in INPULSIS-1 & -2, a randomized, double-blind, placebo controlled, 52-week duration, phase III trial, with the rate of decline of forced vital capacity (FVC) in a patient with idiopathic pulmonary fibrosis significantly reduced at the end of the study

Pirfenidone

  • A synthetic pyridone compound & an antibiotic agent that:
    • Inhibits the transforming growth factor beta (TGF-β)
    • Decreases the extracellular matrix
    • Blocks fibroblast proliferation in vitro 
  • Recommended for patients with mild-to-moderate disease
  • Slows the progression of lung impairment in patients with pulmonary fibrosis due to Hermansky-Pudlak syndrome
  • Based on the 2 Clinical studies Assessing Pirfenidone in idiopathic pulmonary fibrosis 004 & 006 (CAPACITY), Pirfenidone reduced both all-cause & IPF-related mortalities at 52 weeks
  • ASsessment of Pirfenidone to Confirm Efficacy aND safety of idiopathic pulmonary fibrosis (ASCEND) is a randomized, placebo-controlled, double-blind trial that was required by the US Food & Drug Administration (US FDA) to confirm its effectivity on disease progression showed a reduction in the decline of forced vital capacity at week 52 & a decrease by 43% to the risk of death
  • The safety of both trials (ASCEND & CAPACITY) were both demonstrated

Systemic Glucocorticoids

  • Recommended for confirmed idiopathic pulmonary fibrosis during acute exacerbations
  • The given dose is tapered based on the severity of the disease & patient's response to therapy
    • In patients who responds to therapy, the dose is slowly tapered (weeks-months)
    • Patients are then closely followed-up & monitored, to ensure that there is no recurrence of the disease

Other Treatments

  • Use of Ambrisentan, Warfarin, Imatinib, or combination Prednisone/Azathioprine/N-acetylcysteine for idiopathic pulmonary fibrosis is not strongly opposed by the American Thoracic Society, European Respiratory Society, Japanese Respiratory Society, & the Latin American Thoracic Association
  • Treatment with Sildenafil, Bosentan, Macitentan, or N-acetylcysteine monotherapy for idiopathic pulmonary fibrosis is not recommended but may be considered in special conditions
    • Some studies cited improvement in shortness of breath, quality of life, arterial oxygen saturation with Sildenafil use
    • Two studies reported improvements in 6MWT distance while other studies have not found any significant difference in patients given N-acetylcysteine monotherapy
    • Further studies are needed to weigh the use of Sildenafil, Bosentan, Macitentan, & N-acetylcysteine monotherapy in idiopathic pulmonary fibrosis

Non-Pharmacological Therapy

Home Pulse Oximetry

  • It is noninvasive & is used to assess arterial oxygen saturation of hemoglobin (SpO2)
    • Light-absorbing variations from arterial blood flow pulsation are measured 
  • Used for monitoring & maintaining of the SpO2 level to >90%
    • If maintained, the development of a secondary pulmonary hypertension would be prevented

Supplemental Oxygen Therapy

  • Patients with acute exacerbation of idiopathic pulmonary fibrosis have a high oxygen requirement because they need to maintain a pulse oxygen saturation of >88%
  • In patients with acute exacerbation of idiopathic pulmonary fibrosis, hypoxemia is treated with supplemental oxygen
    • This may be sufficient to treat dyspnea but they must be monitored regularly as dyspnea due to idiopathic pulmonary fibrosis may be refractory 
  • Dyspnea upon exertion may be relieved by ambulatory or long-term oxygen therapy
  • Long-term oxygen therapy is recommended for idiopathic pulmonary fibrosis patients with clinically significant resting hypoxemia
  • Mechanical ventilation is not recommended for acute exacerbation of idiopathic pulmonary fibrosis

Pulmonary Rehabilitation

  • It improves symptoms, capacity to do exercises (eg walking distance) & quality of life, & reduces the severity of dyspnea of patients with idiopathic pulmonary fibrosis
  • The rehabilitation programs should be based on the severity of the disease

Clinical Trials

  • Patients with idiopathic pulmonary fibrosis are encouraged to join & participate in clinical trials of emerging therapies
    • The ideal candidate for a clinical trial is a patient with mild to moderate idiopathic pulmonary fibrosis 
  • Information about the trial will be provided for each patient & its assignment would depend on the patient’s assessment & condition
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