Which of these is an example of a long-acting beta 2 adrenergic agonist?

Long-acting beta 2 adrenergic agonists (LABAs) are medications primarily used to manage and control asthma and chronic obstructive pulmonary disease (COPD) by providing prolonged bronchodilation. Salmeterol is classified as a LABA and is recognized for its extended duration of action, allowing for twice-daily dosing to maintain bronchial dilation over a longer period compared to short-acting agonists.

Salmeterol works by selectively stimulating beta-2 adrenergic receptors in the airway smooth muscle, leading to muscular relaxation and bronchodilation. This effect is beneficial for patients who require ongoing relief from bronchospasm related to respiratory conditions.

Other options listed do not fit the criteria for long-acting beta 2 adrenergic agonists. For instance, albuterol is a short-acting beta agonist, commonly used for quick relief in acute asthma exacerbations rather than as a long-term management strategy. Formoterol is another long-acting agent but is not the correct choice in this context. Ipratropium bromide is an anticholinergic medication, not a beta-adrenergic agonist, focusing on a different mechanism to relieve airway constriction.