SABA & LABA

Question 1

List the problems with adrenaline

Answer 1

• Short duration of action
• Poor selectivity & specificity

Question 2

What does the isopropyl unit give in the term of specificity?

Answer 2

Active towards B-receptors and not a-receptors

Question 3

Describe how selectivity and potency is increased via extensions/ additions to a-methyl noradrenaline.

Answer 3

• Adding a Me group to a C promotes binding to a2-R.
• Adding a distant H bond group increases potency while retaining B-selectivity.

Question 4

Give 1 example of B2-adrenergic agonist

Answer 4

R-salbutamol

Question 5

Describe the results and effects on metabolism in R-salbutamol due to the extension between the HO group and phenol.

Answer 5

• Can H bond to serine residues in adrenergic-Rs
• Not metabolised by COMT giving short duration of action allowing agonist activity.

Question 6

How long is the duration of action os SABAs?

Answer 6

4-6 hours

Question 7

Describe approach for dealing with COMT in terbutaline.

Answer 7

• Not a catechol due to shift of the -OH group
• Can H bind to serine residues binding to adrenergic receptors allowing agonist activity.

Question 8

Give one example of a LABA and state its duration of action.

Answer 8

Salmeterol - 12 hours

Question 9

Which portion of LABAs e.g. salmeterol produce longer acting drugs and why?

Answer 9

The hydrophobic tail
- Increases hydrophobicity causes this portion of the drug to be retained in tissue near the A-R for a longer amount of time - increasing longer duration of action.