Respiratory Pharmacology 2 Flashcards
What are the reliever drugs for asthma?
- Β-2 agonists
- methylxanthines
- Anti-muscarinics
What are the preventer drugs for asthma?
- Corticosteroids
- Cromones
- Anti-leukotrienes
- Anti-IgE
Describe cromones as preventers
- Sodium cromoglycate (Intal)
- Nedocromil sodium (Tilade)
- Dry inhaler for prophylaxis
- Eye and nasal drops
- Most effective inchildren
- Excellent safety profile
- Short half-life- 4x daily
- More times taken, less compliant patient will be to complex medication routine
Describe the arachidonic acid cascade
- Arachidonic acid
- Cyclo-oxygenase–> prostaglandins, thromboxane and prostacyclin
- 5-lipoxygenase–> LTA4
- -> Cys-LT–> receptors –> bronchoconstriction, eosinophil recruitment, mucous secretion microvascular leak
- -> LTB4
Describe the use of anti-leukotrienes as preventers
- Target- 5-LO inhibitor- Zileurton
- Common receptor antagonist- Montelukast and Zadirlukast
- Antagonists of the Cys-LT receptors on smooth muscle and eosinophils
- Oral prophylaxis for persistent asthma
What is the effect of anti-leukotrienes as preventers?
- Bronchodilation- reduces frequency and severity of asthma attacks
- Anti-inflammatory- reduces eosinophilia
- Reduces comorbidities- allergic rhinitis
- Paediatric formulations- inhalers might be difficult for them to use
- Generally safe with minimal side effects
Describe the use of Anti-IgEs as preventers
- Omalizumab (Xolair)
- Humanised anti-IgE - 3% mouse protein
- Binds IgE in plasma- does not cause mast cell degranulation
- Moderate/severe uncontrolled asthma
- Expensive and risk of anaphylaxis
- Cumulative risk of anaphylaxis
Compare oral and inhaled therapy in terms of form of preparation and ideal pharmacokinetics
- inhaled prep: aerosol/dry pwder
- Oral prep: tablet/liquid
- Ideal pharmacokinetics
- -> inhaled: slow absorption from lung, rapid systemic clearance
- -> Oral: good absorption, long systemic clearance
Compare oral and inhaled therapy in terms of dose and side effects
- Inhaled: low direct dose to lung, low local side effects
- Oral: high dose, high side effects dependent on drugs
Compare oral and inhaled therapy in terms of access to lung and compliance
- Inhaled: poor access, poor compliance
- Oral: good access, good compliance (easier to use)
Compare oral and inhaled therapy in terms of ease of use and effectiveness
- Inhaled: difficult to use, effective in mild disease
- Oral- easy to use and effective, even in severe disease
What is the treatment for acute severe asthma?
- Status asthmaticus
- Treatment
- -> oxygen, nebuliser β-2-agonist, oral prednisolone or IV hydrocortisone
- No improvement in 15-20 minutes
- -> continue oxygen and β-2 agonist, Ipatropium and Mg2+, admit to hospital
What are the principles of asthma therapy?
- Mild/intermittent- short-acting β-2 agonist
- Mild persistent- low-dose inhaled GCS
- Moderate persistent
- -> High dose inhaled GCS + salmeterol
- -> Or, anti-LT or ipratrpium or the ophylline or cromone
- Severe persistent–> oral GCS
Why does asthma treatment fail?
- Intentional non-adherence
- -> patient feels better and stops taking medication
- -> Dislike adverse effect
- Unintentional non-adherence
- -> Poor inhaler technique- may use them wrong
- -> Complex dosing/drug regimen (forgetting to take it)
What are asthma phenotypes?
- Inflammation and symptoms
- Inflammation predominant-> fever symptoms
- Symptom predominant –> less inflammation
