Which of the following medications is often used as a rescue inhaler?

Short-acting beta-agonists (SABAs) are commonly used as rescue inhalers because they provide rapid relief of acute bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease (COPD). SABAs work by stimulating beta-2 adrenergic receptors in the bronchial smooth muscles, leading to bronchodilation. This effect typically occurs within minutes and lasts for several hours, making them ideal for immediate symptom relief during an asthma attack or exacerbation.

In contrast, long-acting muscarinic antagonists (LAMAs) are primarily used for maintenance therapy and have a delayed onset of action, making them unsuitable for quick relief. Inhaled corticosteroids are primarily used for long-term control of inflammation in chronic respiratory conditions rather than immediate rescue. Mucolytics help to thin mucus in the airways but do not provide bronchodilation, so they are not effective for acute relief of bronchospasm. Therefore, the unique mechanism and rapid action of short-acting beta-agonists make them the preferred choice for rescue inhalers.