25.0: Introduction
The lower respiratory system (shown in Figure 25.2) plays a crucial role in respiration, allowing the exchange of oxygen and carbon dioxide between the body and the external environment. The lower respiratory system includes the trachea, the lungs, and within the lungs, the bronchi, bronchioles, and alveoli. See Introduction to the Respiratory System for more information on the lower and upper respiratory systems. Various respiratory diseases and disorders can significantly affect the functioning of the lower respiratory system, leading to respiratory distress, impaired lung function, and reduced quality of life. Lower respiratory drugs are a class of medications designed to alleviate symptoms, manage chronic conditions, and improve overall respiratory function.
Respiratory diseases affecting the lower respiratory system can be broadly classified into two categories: obstructive and restrictive lung diseases. Obstructive lung diseases, such as asthma and Chronic obstructive pulmonary disease (COPD) , are characterized by airflow limitation due to inflammation, bronchoconstriction, and increased mucus production. Asthma affects the lungs, causing repeated episodes of wheezing, breathlessness, and coughing. COPD is a group of diseases including emphysema and chronic bronchitis. Emphysema damages the airways and causes chronic inflammation in the lungs. This makes it very difficult for the person to breathe. Chronic bronchitis is a productive cough of more than 3 months, specifically within a span of 2 years (Widysanto & Mathew, 2022).
Restrictive lung diseases, such as pulmonary fibrosis , involve a reduced lung capacity due to impaired lung tissue expansion or chest wall abnormalities (Martinez-Pitre et al., 2023).
Lower respiratory drugs encompass a wide range of pharmacological agents, each targeting specific mechanisms involved in respiratory diseases. These drugs can be administered via various routes, including inhalation, oral ingestion, and intravenous infusion, depending on the medication’s characteristics and the severity of the respiratory condition.