Idiopathic Pulmonary Fibrosis
Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive, and ultimately fatal interstitial lung disease characterized by the accumulation of fibrotic tissue within the pulmonary interstitium, leading to irreversible scarring and impaired gas exchange. The term 'idiopathic' denotes that the cause of the fibrosis is unknown, distinguishing IPF from other forms of interstitial lung diseases with identifiable etiologies. The pathogenesis of IPF is complex and thought to involve aberrant wound healing responses following repeated micro-injuries to the alveolar epithelium, resulting in dysregulated fibroblast proliferation, excessive deposition of extracellular matrix, and architectural distortion of the lung parenchyma. Genetic predispositions, environmental exposures, and aging are considered contributory risk factors. The progressive fibrosis leads to a restrictive ventilatory defect, reduced lung compliance, impaired oxygenation, and ultimately respiratory failure. Health impacts are profound, with patients experiencing progressive dyspnea, chronic cough, decreased exercise tolerance, and a significant reduction in quality of life. The disease has a poor prognosis, with a median survival of 3–5 years from diagnosis.
The classic and most common form of idiopathic pulmonary fibrosis is characterized histopathologically and radiographically by the usual interstitial pneumonia (UIP) pattern. This type exhibits patchy, predominantly subpleural and basal fibrosis, temporal and spatial heterogeneity, and honeycomb changes on high-resolution imaging or histology. UIP-pattern IPF is the definitive diagnosis when clinical, radiological, and, if necessary, pathological criteria are met in the absence of known causes.
A subset of IPF cases occurs in a familial context, defined by the presence of two or more affected individuals within the same family. Familial IPF shares clinical and radiological features with sporadic IPF but is associated with identifiable genetic mutations, such as those affecting telomerase or surfactant protein genes. This form often presents at a younger age and may have a more variable disease course.
This type refers to an acute, clinically significant respiratory deterioration characterized by new, widespread alveolar abnormalities superimposed on chronic fibrotic changes. Acute exacerbations are associated with high morbidity and mortality and may be triggered by infections, procedures, or occur idiopathically. Histologically, these episodes often show diffuse alveolar damage in addition to underlying fibrosis.
Idiopathic pulmonary fibrosis predominantly affects older adults, with the majority of cases diagnosed in individuals over the age of 60. The incidence of IPF is estimated to range between 2 and 30 cases per 100,000 persons per year, with higher rates reported in men than women. Prevalence estimates vary globally, but in North America and Europe, figures typically range from 14 to 63 per 100,000 persons. The disease is rare in individuals under 50 years of age. Risk factors include a history of cigarette smoking, certain occupational and environmental exposures, and genetic predisposition. IPF is associated with significant morbidity and mortality, with a median survival after diagnosis of approximately 3 to 5 years. The disease burden is increasing, likely due to improved recognition, an aging population, and possibly environmental factors.
The diagnosis of idiopathic pulmonary fibrosis is established through a multidisciplinary approach integrating clinical, radiological, and, when necessary, histopathological data. Initial assessment includes a thorough history and physical examination to exclude known causes of interstitial lung disease. High-resolution computed tomography (HRCT) of the chest is the cornerstone of diagnosis, with the presence of a usual interstitial pneumonia (UIP) pattern—characterized by reticular opacities, traction bronchiectasis, and honeycombing in a basal and subpleural distribution—being highly suggestive of IPF. In cases where HRCT findings are not definitive, surgical lung biopsy may be required to obtain histopathological confirmation of UIP. Pulmonary function tests typically reveal a restrictive pattern with reduced forced vital capacity (FVC) and diffusing capacity for carbon monoxide (DLCO). Additional laboratory tests and serologic studies are performed to exclude connective tissue disease and other secondary causes. The diagnostic process is guided by consensus criteria from professional societies, emphasizing the exclusion of alternative diagnoses and the integration of clinical, imaging, and pathological findings.
Nintedanib is an oral tyrosine kinase inhibitor that targets multiple growth factor receptors implicated in fibrogenesis and has been approved for the treatment of idiopathic pulmonary fibrosis to slow the rate of disease progression by reducing the annual decline in forced vital capacity. Pirfenidone is an oral antifibrotic agent with anti-inflammatory and antioxidant properties, indicated for the management of idiopathic pulmonary fibrosis, where it has demonstrated efficacy in slowing the progression of pulmonary function decline and may also reduce the risk of acute exacerbations.
| Structure | Generic Name | CAS Registry Number | Molecular Formula | Molecular Weight |
|---|---|---|---|---|
 | intedanib; nintedanib (USAN) | 656247-17-5 | C31 H33 N5 O4 | 539.625 |
 | pirfenidone (Rec INN; USAN) | 53179-13-8 | C12 H11 N O | 185.222 |
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