This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Asthma, Subject name: Pharmacology
Mechanism of action of Salmeterol is: 
Select and explain. 
A. Pure b2 agonist, B. Pure b1 agonist, C. b1 + b2 agonist, D. al agonist
A: Pure b2 agonist
Answer: A: Pure b2 agonist 
Explanation: Ans. is 'a' i.e., Pure b2 agonist Salmeterol* It is the first long acting p2 agonist with slow onset of action used by inhalation on a twice daily schedule for maintenance therapy, but not for acute asthma.* Concurrent use of inhaled salmeterol and inhaled glucocorticoids produces effects equivalent to double dose of corticosteroid alone.