What type of medication is typically administered via a Metered-Dose Inhaler (MDI)?

Metered-Dose Inhalers (MDIs) are specifically designed to deliver medications directly to the lungs in a measured dose, making them particularly effective for treating respiratory conditions. Bronchodilators, which include short-acting and long-acting agents, are commonly administered through MDIs. These medications work by relaxing the muscles of the airways, facilitating an increase in airflow and alleviating symptoms associated with conditions such as asthma and chronic obstructive pulmonary disease (COPD).

This direct delivery method allows for quick action and minimizes systemic side effects, as the medication primarily acts where it is needed — in the lungs. While antibiotics, systemic steroids, and oral antihistamines have important roles in respiratory therapy, they are not typically delivered via MDIs. Antibiotics are usually systemic for infections, systemic steroids require a different route for effective treatment of inflammation, and oral antihistamines are used principally for allergic reactions and are not suitable for inhalation. Thus, bronchodilators are the primary medication type administered via an MDI, making it the correct choice.