What type of medication is commonly delivered via a metered-dose inhaler (MDI)?

A metered-dose inhaler (MDI) is primarily utilized for delivering medication directly to the lungs, which makes it particularly effective for respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). The medications most commonly associated with MDIs include bronchodilators, which are specifically designed to relax the muscles of the airways, thereby improving airflow to the lungs. This action helps to relieve symptoms such as wheezing, shortness of breath, and chest tightness, making bronchodilators the preferred choice for immediate relief in acute situations.

While corticosteroids can also be delivered via MDIs, they are typically used for chronic management to control inflammation and are often prescribed in tandem with bronchodilators. Antibiotics target infections and are usually administered through other routes, such as oral or intravenous, rather than through an inhaler. Antihistamines are generally intended for allergic reactions and are also not typically delivered through an MDI, as they're primarily used for systemic effects instead of localized respiratory treatment. Therefore, the primary role of the MDI is to deliver bronchodilators effectively, making this choice the most appropriate for the given question.