Asthma treatment Flashcards
What is the aim of asthma treatment?
- no daytime symtpoms
- No night time awakening
- No need for rescue medication
- no asthma attacks
- No limitations on activity including exercise
- normal lung function
- Minimal side effects from medications
Who gets an intermittent reliever?
Anyone with diagnosis of asthma
What are the short acting bronchodilators?
- Inhaled short acting B2 agonists
- Inhaled ipratropium bromide
- Theophyllines
When should you consider an inhaled corticosteroid for an asthmatic patient?
- Asthma attack in the past two years
- Using inhaled B2 agonist three times a week or more
- Symptomatic three times a week or more
- Waking one night a week
Explain starting a corticosteroid as preventer therapy
- start at a dose appropriate to the severity of the disease
- titrate the dose to the lowest dose at which effective control of asthma is maintained
- Smoking previous or current reduces the effect of ICS so consider higher doses
What is the mechanism of action of an ICS?
- Bind to activated glucocorticoid receptors
* Suppress multiple pro-inflammatory genes that are activated in asthmatic airways by reversing histone acetylation
What are the indications for an ICS?
- Asthma
* COPD with recurrent exacerbation
What are the side effects of corticosteroids?
- Diabetes
- Osteoporosis
- HTN
- Muscle wasting
- Peptic ulceration
- Cataracts
- Cushings
- Adrenal suppression
- Acute pancreatitis
- Hyperlipidaemia
- Increased appetite
- Salt and water retention
- Immune suppression
What is the first line preventer drug?
Inhaled corticosteroid
What are the non first line preventer therapies for patients taking beta 2 agonist alone
- Leukotriene receptor antagonists
- Sodium cromoglicate and nedocromil sodium
- Theophyllines
If asthma is not adequately controlled with a low dose ICS what are the next steps?
- Recheck adherence, inhaler technique and trigger factors
- First choice add on in adults is an inhaled long acting beta 2 agonist
- This should be considered before upping dose of ICS or adding leukotriene receptor antagonist
What is MART?
- Combination of maintenance and preventer therapy
* Ensures that as the need for a reliever increases, the dose of the preventer is also increased
What should you do if asthma control is inadequate on medium dose of inhaled corticosteroid with a long acting beta 2 agonist or LTRA?
•Increase ICS to high or add LTRA (if not on) or add tiotropium/theophylline
Name 2 LTRAs
- Montelukast
* Zafirlukast
What is the mechanism of action of LTRAs?
- High affinity antagonist of cysteinyl leukotriene receptor inhibiting the action of LT-D4 in smooth muscle cells of the airway and airway macrophages
- Reduces the airway oedema and smooth muscle contraction
Which types of asthma are LTRAs especially useful for?
The phophylaxis of exercise induced asthma and allergic rhinitis
Name a short acting anti-muscarinics
Ipratropium bromide
Name a long acting anti-muscarinic
Tiotropium
What is the mechanism of action of the anti-muscarinics?
- Antagonist of cholinergic M1 and M3 receptors in the lung
- Stops broncho-constriction due to muscarinic receptor activation (connected to Gq-G portions, phospholipase IP3 and intracellular Ca2+)
- On vasculature, M3 activation increases NO production causing vasodilation
What are the indications of anti-muscarinics?
- Asthma
* COPD
What are the side effects of the anti-muscarinics?
- Blurred vision
- Dry mouth
- Urinary retention
- Nausea
- Constipation
What is a side effect specifically of nebuliser ipratroprium?
- Acute angle closure glaucoma
* Use a mouthpiece not a mask
How are anti-muscarinincs excreted?
Renally
What is the mechanism of action of methxanthines?
- Non selective inhibition of phosphdiesterases
- This increases intracellular cAMP
- Bronchial smooth muscle relaxation
- Immunomodulatory effect - improves mucociliary clearance and anti-inflammatory effect (decreases leukotrienes and TNFa)
Name a methylxanthine
- Theophylline
* Aminophylline is a mix of theophylline and ethylenediamine
What are the indications of methxanthines?
•Adjunct to inhaled therapy in asthma/IV infusion in severe exacerbations of asthma
What are the side effects of methylxanthines?
- GI upset
- Palpitations
- Tachycardia
- Headache
- Insomnia
- Hypokalaemia
Toxicity of methyxanthines
- Severe vomiting
- Hypokalaemia/hypocalcaemia
- Seizure
- Arrhythmia
- Hypotension
Where are methxanthines metabolised?
In the liver - cautioned in liver disease and with concomitant use of some antibiotics
What increases theophylline clearance?
Smoking
When should you consider the use of monoclonal antibodies in asthma?
In high burden of corticosteroid
Name a monoclonal antibody used in asthma
Omalizumab
What is omalizumab?
- anti IgE antibody
- Used in severe persistant allergic asthma
- Subcutaneous injection ever 2-4 weeks
- Risk of severe hypersensitivity reaction
What is mepolizumab?
•Anti IL-5 monoclonal antibody •Reduces circulating eosinophils •Used in severe refractory eosinophilic asthma •Subcut every 4 weeks •Headache common
Acute severe asthma
Any one of •PEF 33-50% best or predicted •HR >110bpm •RR ≥ 25/min •Inability to complete sentences in one breath
Life threatening asthma
Any one of: •Altered consciousness • exhaustion •Arrhythmia •Hypotension •Cyanosis •Silent chest •Poor respiratory effort •PEF <33% best or predicted •SpO2 < 92% •PaO2 <8kPa •Normal PaCO2
Near fatal asthma
- Raised PaCO2
* And/or requiring mechanical ventilation with raised inflation pressures
What is the management of life threatening acute exacerbation of asthma
- Supplemental oxygen to maintain spO2
- Nebulised bronchodialtors 5mg salbutamol
- Oral prednisolone 40mg to reduce bronchial inflammation
- Oral doxycycline 200mg if chest infection suspected
- IV magnesium 2g - relaxation of smooth muscle and blocking histamine release from mast cells
- Consider IV aminophylline infusion
