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Pulmonary Fibrosis
Introduction
Introduction
Pulmonary fibrosis (PF) is one of a lung disease that can result in lung scarring. The word "pulmonary" means “lung” and the word "fibrosis" means accumulation of excess of fibrous connective tissue or in common language scar tissue - similar to scars that you may have on your skin from an old injury or surgery. So, in its simplest sense, PF means scarring in the lungs. As the lung tissue becomes scarred (stiff and thickened tissue), it interferes with a person's ability to breathe and reduces oxygen supply to the blood, resulting into the shortness of breath. In some cases, the cause of pulmonary fibrosis can be found. But most cases of pulmonary fibrosis have no known cause (etiology). When exact reason of occurrence of any disease is not clearly recognized, the condition is called as “idiopathic”. Therefore, these cases are called idiopathic pulmonary fibrosis (IPF). As mentioned; PF isn’t just one disease. It is a family of more than 200 different lung diseases that all look very much alike. The PF family of lung diseases falls into larger group of diseases called the interstitial lung diseases (ILD). Some interstitial lung diseases don't include scar tissue as that of PF [1].
Pulmonary fibrosis (PF) is one of a lung disease that can result in lung scarring. The word "pulmonary" means “lung” and the word "fibrosis" means accumulation of excess of fibrous connective tissue or in common language scar tissue - similar to scars that you may have on your skin from an old injury or surgery. So, in its simplest sense, PF means scarring in the lungs. As the lung tissue becomes scarred (stiff and thickened tissue), it interferes with a person's ability to breathe and reduces oxygen supply to the blood, resulting into the shortness of breath. In some cases, the cause of pulmonary fibrosis can be found. But most cases of pulmonary fibrosis have no known cause (etiology). When exact reason of occurrence of any disease is not clearly recognized, the condition is called as “idiopathic”. Therefore, these cases are called idiopathic pulmonary fibrosis (IPF). As mentioned; PF isn’t just one disease. It is a family of more than 200 different lung diseases that all look very much alike. The PF family of lung diseases falls into larger group of diseases called the interstitial lung diseases (ILD). Some interstitial lung diseases don't include scar tissue as that of PF [1].
Prevalence
Prevalence
The estimated prevalence of IPF in the United States (US) ranges from 14 - 43 per 100,000 populations. Although the disease is commonly encountered in tertiary care centres in India, it remains under diagnosed at the primary care level. Despite being well recognized in the West, the entity has still not received due attention in India, and is often lumped under the broad category of interstitial lung disease (ILD). The population prevalence of the disease in the country is not known. It is speculated that it should be as prevalent as in other regions of the world. Among patients with diffuse parenchymal lung diseases, 29-48% patients had IPF in four studies from tertiary care centres in India [1].
The estimated prevalence of IPF in the United States (US) ranges from 14 - 43 per 100,000 populations. Although the disease is commonly encountered in tertiary care centres in India, it remains under diagnosed at the primary care level. Despite being well recognized in the West, the entity has still not received due attention in India, and is often lumped under the broad category of interstitial lung disease (ILD). The population prevalence of the disease in the country is not known. It is speculated that it should be as prevalent as in other regions of the world. Among patients with diffuse parenchymal lung diseases, 29-48% patients had IPF in four studies from tertiary care centres in India [1].
Probable causes
Probable causes
Researchers have several theories about what might trigger IPF, including autoimmune disorders, viral and bacterial infections and exposure to tobacco smoke or environmental pollutants like inorganic or organic dust. Also, some forms of idiopathic pulmonary fibrosis run in families and heredity which points to a genetic predisposition in a subset of patients [2].
Researchers have several theories about what might trigger IPF, including autoimmune disorders, viral and bacterial infections and exposure to tobacco smoke or environmental pollutants like inorganic or organic dust. Also, some forms of idiopathic pulmonary fibrosis run in families and heredity which points to a genetic predisposition in a subset of patients [2].
Symptoms
Symptoms
The more common clinical symptoms of the disease are progressive breathlessness and dry cough which is usually misdiagnosed with Chronic Obstructive Pulmonary Disease (COPD) in smokers. Other symptoms which may accompany the conditions are fatigue, unexpected weight loss, muscle and joint pain etc.
The more common clinical symptoms of the disease are progressive breathlessness and dry cough which is usually misdiagnosed with Chronic Obstructive Pulmonary Disease (COPD) in smokers. Other symptoms which may accompany the conditions are fatigue, unexpected weight loss, muscle and joint pain etc.
Diagnosis
Diagnosis
Despite the availability of guidelines for diagnosis and treatment, the disorder is neither diagnosed properly nor treated well in India. Most of the patients are diagnosed late in the course of the disease. Due to similarity in the symptoms with other lung disease and lack of awareness about the patient history and insufficient physical examination, physicians usually misdiagnose IPF as COPD. In addition, initial investigating tools such as - spirometry, chest radiograph, and high resolution computed tomography (HRCT) are either not available or not applied. Overall, prognosis for patients with IPF remains very poor, with median survival of about 3 years [3].
Despite the availability of guidelines for diagnosis and treatment, the disorder is neither diagnosed properly nor treated well in India. Most of the patients are diagnosed late in the course of the disease. Due to similarity in the symptoms with other lung disease and lack of awareness about the patient history and insufficient physical examination, physicians usually misdiagnose IPF as COPD. In addition, initial investigating tools such as - spirometry, chest radiograph, and high resolution computed tomography (HRCT) are either not available or not applied. Overall, prognosis for patients with IPF remains very poor, with median survival of about 3 years [3].
Treatment
Treatment
Corticosteroids, azathioprine, and N-acetylcysteine (NAC) have been used in the past to treat this disorder in various combinations. Recently, the PANTHER-IPF trial showed that a combination of these three agents increases mortality and should not be used. Monotherapy with NAC is also ineffective. The only two agents that have been shown to have clinical benefits in treating IPF are the antifibrotic agents pirfenidone and nintedanib [4].
Corticosteroids, azathioprine, and N-acetylcysteine (NAC) have been used in the past to treat this disorder in various combinations. Recently, the PANTHER-IPF trial showed that a combination of these three agents increases mortality and should not be used. Monotherapy with NAC is also ineffective. The only two agents that have been shown to have clinical benefits in treating IPF are the antifibrotic agents pirfenidone and nintedanib [4].
Pirfenidone has been available in India since 2010 and was approved by the Food and Drug Administration (FDA) of the US in 2014. These drugs were evaluated for IPF in multinational randomized controlled trials at Japan, United States, Europe and Australia. While the doses of this drug used in the CAPACITY and ASCEND trials were 1200 mg/day and 2400 mg/day of which the 2400 mg dose was more effective, the appropriate dose for the Indian population is unknown. There is an urgent need to generate clinical efficacy and safety data on the appropriate dosing of this drug in the Indian population.
Pirfenidone has been available in India since 2010 and was approved by the Food and Drug Administration (FDA) of the US in 2014. These drugs were evaluated for IPF in multinational randomized controlled trials at Japan, United States, Europe and Australia. While the doses of this drug used in the CAPACITY and ASCEND trials were 1200 mg/day and 2400 mg/day of which the 2400 mg dose was more effective, the appropriate dose for the Indian population is unknown. There is an urgent need to generate clinical efficacy and safety data on the appropriate dosing of this drug in the Indian population.
References
References
1. Kolb M, Bonella F, Wollin L. Therapeutic targets in idiopathic pulmonary fibrosis. Respir Med. 2017; 131:49-57.
1. Kolb M, Bonella F, Wollin L. Therapeutic targets in idiopathic pulmonary fibrosis. Respir Med. 2017; 131:49-57.
2. Dhooria S, Agarwal R. Idiopathic pulmonary fibrosis in India. Chest India Edition. 2015, 147:1-3.
2. Dhooria S, Agarwal R. Idiopathic pulmonary fibrosis in India. Chest India Edition. 2015, 147:1-3.
3. Raghu G, Richeldi L. Current approaches to the management of idiopathic pulmonary fibrosis. Respir Med. 2017; 129:24-30.
3. Raghu G, Richeldi L. Current approaches to the management of idiopathic pulmonary fibrosis. Respir Med. 2017; 129:24-30.
4. Xaubet A, Ancochea J, Molina-Molina M. Idiopathic pulmonary fibrosis. Med Clin (Barc). 2017; 148:170-175.
4. Xaubet A, Ancochea J, Molina-Molina M. Idiopathic pulmonary fibrosis. Med Clin (Barc). 2017; 148:170-175.
Contributor:
Abhijeet D. Kulkarni MPharm, PhD
Assistant Professor
Department of Quality Assurance
R.C. Patel Institute of Pharmaceutical Education & Research
Shirpur Taluka, Dhule District, Maharashtra, 425 405.
Reviewer:
Mohammad Khan MD, PhD
Children's Hospital of Philadelphia
University of Pennsylvania, Philadelphia, PA, USA
March 2018
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