Sheep anti-Salmeterol polyclonal antibody. Salmeterol is a long-acting beta2-adrenergic receptor agonist drug that is currently prescribed for the treatment of asthma and chronic obstructive pulmonary disease(COPD). It is currently available as a dry powder inhaler that releases a powdered form of the drug. Before 2008, it was also available as a metered-dose inhaler (MDI).