RESP: BETA-2-AGONISTS

Question 1

BETA-2-AGONISTS: INDICATIONS

Answer 1

• Asthma
• COPD
• Hyperkalaemia

Question 2

BETA-2-AGONISTS: MOA

Answer 2

• These receptors are found in smooth muscle of the bronchi, GIT, uterus and blood vessels
• Stimulation of the GPCR = signalling cascade that leads to smooth muscle relaxation
• Improves airflow in constricted airways, reducing the symptoms of breathlessness
• B2 agonists stimulate Na+/K+-ATPase pumps on cell surface membranes, thereby causing a shift of K+ from the extracellular to the intracellular component

Question 3

BETA-2-AGONISTS: ADVERSE EFFECTS

Answer 3

• Activation of these receptors accounts for the common flght vs flight advers effects of tachycardia, palpitations, anxiety and tremors
• Promote glycogenolysis, so may increase the serum glucose concentration
• High levels serum lactate levels rise, so LABA can cause muscle cramps

Question 4

BETA-2-AGONISTS: WARNINGS

Answer 4

• Without inhaled steroid, LABA are associated with asthma related deaths
• Take care when prescribing in patients with CVD, as can provoke arrhythmias

Question 5

BETA-2-AGONISTS: INTERACTIONS

Answer 5

• Beta blockers
• Concomitant use of high-dose nebulised b2 agonists with theophylline and corticosteroids can lead to hypokalaemia, so serum potassium concentrations should be monitored