Beta agonist

Question 1

Beta-2 agonist - examples of SABA

Answer 1

Short acting beta agonists (SABA):
○ Salbutamol
○Terbutaline

Question 2

Beta-2 agonist - examples of LABA

Answer 2

Long acting beta agonists (LABA)
○ Salmeterol
○ Formoterol

Question 3

Beta-2 agonist - indications

Answer 3

Asthma

COPD

Hyperkalaemia

Question 4

Beta-2 agonist - why are SABAs given for asthma and COPD?

Answer 4

SABA are used to relieve SOB

Question 5

Beta-2 agonist - why are LABAs given for asthma

Answer 5

LABA are used to treat chronic asthma when inhaled corticosteroids (ICS) alone are insufficient - therefore given in combination with inhaled corticosteroids (ICS)

REMEMBER - LABA HAS TO BE GIVEN WITH ICS

Question 6

Beta-2 agonist - why are LABAs given for COPD

Answer 6

LABA are an option for second-line therapy of COPD to improve symptoms and reduce exacerbations

Question 7

Beta-2 agonist - MOA

Answer 7

B2R are found in the smooth muscle of the bronchi, gut, uterus and blood vessels

ASTHMA/COPD
○ B2 agonists stimulate B2R - leading to smooth muscle relaxation
○ Improves airflow in airways - leading to reduced symptoms of SOB

HYPERKALAEMIA
○ B2 agonists stimulate Na+/K+ ATPase pumps
○ shifts K+ from extracellular to intracellular compartments
○ useful to treat hyperkalaemia

Question 8

Beta-2 agonist - adverse effects

Answer 8

tachycardia

palpitations

anxiety

tremors

LABAs may also cause muscle cramps

Question 9

Beta-2 agonist - interactions

Answer 9

beta blockers

monitor serum potassium if using B2 agonists alongside theophylline +/- corticosteroids - can lead to hypokalaemia

Question 10

Beta-2 agonist - administration

Answer 10

aerosols or dry powder

patients can take inhalers using spacer with MDI - benefits:
○ improve airway deposition of drug
○ improve treatment efficacy
○ reduce oral adverse effects

Question 11

Beta-2 agonist - monitoring

Answer 11

ASTHMA
○ monitor their disease severity through their symptoms and by serial measurements of peak expiratory flow rate (PEFR)

Likewise, symptom severity and exacerbation rates are the main indicators of effect in COPD.

Question 12

Beta-2 agonist - caution

Answer 12

Care should be taken when prescribing β2-agonists for patients with cardiovascular disease, in whom tachycardia may provoke angina or arrhythmias. This is especially pertinent in the treatment of hyperkalaemia, when high doses may be necessary.

Question 13

What has to ALWAYS be given alongside a LABA?

Answer 13

Long-acting β2 agonists should be used in asthma only if an inhaled corticosteroid is also part of therapy.

REMEMBER:
ICS can be given W/O LABA
(ICS = I = independent)

BUT

LABA has to be given WITH ICS