Which of the following drugs is an example of a nonselective bronchodilator?

Racemic epinephrine is classified as a nonselective bronchodilator because it acts on both beta-1 and beta-2 adrenergic receptors. This dual action results in increased heart rate and bronchodilation, making it effective in treating conditions such as croup or upper airway swelling. The stimulation of beta-2 receptors primarily leads to relaxation of bronchial smooth muscle, promoting airway dilation.

The other options listed serve different functions or are selective in their action. Levalbuterol, for instance, is a selective beta-2 agonist, which means it primarily targets the beta-2 receptors without significantly affecting beta-1 receptors, thus minimizing cardiovascular side effects. Ipratropium is an anticholinergic medication, working through a different mechanism to reduce bronchospasm by inhibiting the action of acetylcholine on bronchial smooth muscle. Methylprednisolone is a corticosteroid that reduces inflammation rather than acting directly as a bronchodilator. This distinction helps clarify why racemic epinephrine stands out as a nonselective bronchodilator in this context.