BASIC - RESPIRATORY Flashcards
Names of short/long-acting beta-2-agonists?
- Short-Acting
o Salbutamol, Terbutaline - Long-Acting
o Salmeterol, formoterol
Indications of beta-2-agonists?
- Asthma – short acting as step 1, long-acting as step 3 (must be given with inhaled corticosteroids)
- Hyperkalaemia – nebulised salbutamol (in addition to insulin, glucose, calcium gluconate) in emergency treatment
Mechanisms of beta-2-agonists?
- Beta2-receptors found in smooth muscle of bronchi, GI tract, uterus, blood vessels
- Stimulation of GPCR leads to smooth muscle relaxation – improves airflow
- Stimulate Na/K/ATPase pump causing K+ to move into cells – treat hyperkalaemia in addition to insulin
Side effects of beta-2-agonists?
- ‘Fight-or-flight’ effects
o Tachycardia, palpitations, anxiety, tremor - Gluconeogenesis, may increase serum glucose
- High doses
o Serum lactate levels increased - Long-acting
o Muscle cramps
Interactions of beta-2-agonists?
- Beta-blockers reduce effectiveness
- Hypokalaemia
o Concomitant use with theophylline, corticosteroids
What must long-acting beta-agonist be prescribed with?
- Long-acting only prescribed in asthma with inhaled corticosteroid
o As associated with increased asthma deaths
Cautions of beta-2-agonists?
o CVD – tachycardia promote angina, arrhythmias
o Hypokalaemia
o Diabetes
Prescription of beta-2-agonists?
- PRN prescription
o Use 2 puffs every 4 hours, up to 10 if needed
o If more, then hospital - Can be administered aerosol (MDI), dry powder, nebulised, in combination with steroid (Symbicort, Seretide)
- Spacer provided to improve airway deposition and treatment efficacy
Monitoring asthma?
- Monitored via peak expiratory flow rate (PEFR)
Names of antimuscarinics?
Ipratropium, tiotropium, glycopyrronium
Indications of antimuscarinics?
- Acute exacerbation (short-acting)
- Added in step 4 of chronic asthma (long-acting)
Mechanism of antimuscarinics?
- Bind to muscarinic receptor, competitive inhibitor of acetylcholine
- Stimulation of muscarinic receptor causes ‘rest and digest’ effects
- Blockage has opposite effects:
o Reduced smooth muscle tone
o Reduced secretions
o Relaxation of pupillary constrictor and ciliary muscles – pupil dilatation and preventing accommodation – blurred vision
Side effects of antimuscarinics?
- Little systemic absorption
- Blurred vision, urinary retention, constipation, dry mouth
Cautions of antimuscarinics?
o Angle-closure glaucoma
o Arrhythmias
Contraindications of antimuscarinics?
o Hypersensitivity to atropine or derivatives
Prescription of antimuscarinics?
- Short-acting used QDS or PRN
- In acute asthma
o 0.25mg in 4mL saline
o Every 20-30 mins for 1st 2 hours then every 8 hours if needed
Indications of theophylline?
- Chronic asthma
- Severe acute asthma
- Reversible airway obstruction (COPD)
Mechanism of theophylline?
- Xanthine derivative
- Competitively inhibits PDE 3 and 4 and also binds to adenosine A2B receptor
- Smooth muscle relaxation (bronchodilation) and suppression of airway response to histamine, methacholine, adenosine, allergens
Side effects of theophylline?
- Narrow therapeutic window
- GI upset – nausea, diarrhoea
- Tachycardia, Arrhythmias
- Headaches, insomnia, dizziness
- Hypokalaemia
- Overdose (>10mg/litre)
o Vomiting, agitation, dilated pupils, sinus tachycardia, convulsions
Cautions of theophylline?
- Arrhythmias
- Elderly
- Epilepsy
- Risk of hypokalaemia
Interactions of theophylline?
- Affected by CYP450 enzymes
- Reduce dose in hepatic impairment
Advice on taking theophylline?
- Avoid alcohol, excessive caffeine
- Take with food, swallow whole
Monitoring of theophylline?
o Plasma theophylline concentrations measured 5 days after oral treatment and >3 days after dose changes
Names of inhaled corticosteroids?
Beclomethasone (Clenil Modulite 50mcg lower-potency, Clenil 200mcg), budesonide, fluticasone
Indications of inhaled corticosteroids?
Step 2 of therapy in chronic asthma – not controlled by short-acting B2 agonists
Chronic obstructive pulmonary disease (COPD) – usually with LABA/LAMA
Mechanism of inhaled corticosteroids?
- Pass through plasma membrane and activate receptor which:
o Upregulation of anti-inflammatory proteins
o Downregulates pro-inflammatory interleukins, cytokines, chemokines - Effects
o Reduces mucosal inflammation
o Widens the airways
o Reduces mucus secretion
Side effects of inhaled corticosteroids?
- Occur locally in the airway
o Oral candidiasis
o Hoarse Voice - Few systemic effects unless at very high dose which may cause adrenal suppression, growth retardation and osteoporosis
Doses of inhaled corticosteroids?
- Inhalation of powder (circle one) o Child 5-11 years 100-200mcg BDS o Child 12-17 years & adults 200-400mcg BDS, can be increased up to 800mcg