Since ritodrine has a bulky N-substituent, it has high β2 selectivity. Also, the 4-hydroxy group on the benzene ring is important for activity as it is needed to form hydrogen bonds.
Due to ritodrine's bulky N-substituent, it shows strong β2 selectivity. Furthermore, the presence of the 4-hydroxy group on the benzene ring is essential for its activity because it facilitates hydrogen bonding.