6838608
Description
Flashcards by Andrew Street, updated more than 1 year ago
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Created by Andrew Street
about 8 years ago
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| Question | Answer |
| Give eg's of & indications for beta2-agonists. | eg's: salbutamol & terbutaline (short acting). Salmeterol & formoterol (long acting). Long acting β2-agonists may be combined in an inhaler with a steroid, eg Symbicort or Seretide Indications: * Asthma - short-acting β2-agonists are used to relieve breathlessness. Long-acting β2-agonists are used as ‘step 3’ Rx for chronic asthma, but must always be given in combination with inhaled corticosteroids. * COPD - short-acting β2-agonists are used to relieve breathlessness. Long-acting β2-agonists are an option for 2nd line therapy of COPD. * Hyperkalaemia - nebulised salbutamol may be used as an additional Rx (alongside insulin, glucose & calcium gluconate) for the urgent Rx of a high serum potassium concentration. |
| MOA of B2-agonists. | Beta2-receptors are found in smooth muscle of the bronchi. Stimulation of this G protein-coupled receptor activates a signalling cascade that leads to smooth muscle relaxation (Gs → ↑AC → ↑cAMP → ↓Ca2+ & ↑PKA = ↓MLCK). β2-agonists also stimulate Na+/K+-ATPase pumps on cell surface membranes, thereby causing a shift of K+ from the extracellular to intracellular compartment. This makes them a useful adjunct in the Rx of hyperkalaemia. Beta2-agonists are classified as short-acting (salbutamol, terbutaline) or long-acting (salmeterol, formoterol) according to their duration of effect. |
| SE's of beta2-agonists. | • Tachycardia • Palpitations • Anxiety • Tremor • Muscle cramps (long-acting) |
| CI's, cautions, & important interactions of beta2-agonists. | CI's: • None Cautions: • Long-acting β2-agonists should be used in asthma only if an inhaled corticosteroid is also part of therapy. • Cardiovascular disease Important interactions: Beta-blockers may reduce the effectiveness of β2-agonists. Concomitant use of high-dose nebulised β2-agonists with theophylline and corticosteroids can lead to hypokalaemia, so serum potassium concentrations should be monitored. |
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