Anti-asthmatic Drugs Flashcards
What are the characteristics of Asthma?
- Chronic Airway Inflammation
- Hyperresponsiveness of the Airway (variable symptoms of wheeze, shortness of breath, and cough)
- Recurrent Reversible Airway Obstruction (Asthma Attacks)
What are some controllers (anti-inflammatory: prevention of recurrent attack)?
Inhaled Corticosteroids (ICS)
Inhaled Na Cromoglycate - mast cell stabiliser
Leukotriene Receptor Antagonist (LTRA) - Montelukast
Anti-IgE mAb (Omalizumab)
Anti-IL-5 mAb (Mepolizumab)/ Anti IL-5R mAb (Benralizumab)
Anti IL-4R mAB (Dupilumab)
What are some Relievers (Bronchodilators: Reversal of Airway Constriction)?
Short Acting (4-6 hrs) Beta Agonists (SABA) Long Acting (12 hrs) Beta Agonists (LABA) Long Acting (24 hrs) Beta Agonists (for COPD) Theophylline Muscarinic Antagonists (SAMA (3-5hrs) and LAMA (24hrs))
What is an example of an inhaled corticosteroid?
Fluticasone
What are some characteristics of inhaled corticosteroids (IHC)?
- highly lipophilic - to get inside cell
- high receptor binding affinity
- requires very low dose
- extensive first pass, less systemic side effects
What are the anti-inflammatory effects of Inhaled Corticosteroids?
- Decreased T cells, Mast Cells, Macrophages, Eosinophils in the airways
- Decreased shedding of epithelial cells
- Increased Macrophage Efferocytosis and Decreased cytokines and proteases
- Increased Annexin A1 and Decreased COX 2, 5-LOX, PLA2 Expression
- Increased B2 Receptors on Airway Smooth Muscle
- Decreased Plasma Exudation/Mucus Secretion
What is the efficacy of Inhaled Corticosteroids?
- Does NOT relax airways directly
- Decrease Airway Hyperresponsiveness in a few weeks
- Decrease Frequency of Asthma Exacerbation
- Possibly prevents airway wall remodelling
- Decrease need for beta agonist
- Decrease risk of death from asthma
What is Inhaled Corticosteroids used for?
- 1st Line of prophylactic Asthma Treatment
2. For Nocturnal Asthma (high frequency of asthma attacks at night)
What are the side effects of inhaled corticosteroids?
- Oropharyngeal Candidiasis
- Dysphonia
- Cough/Throat Irritation
- Easy Bruising of Skin (Elderly)
- Adrenal Suppression
- Posterior Subcapsular Cataracts
- Osteoporosis
What is a Leukotriene Modifier/ Leukotriene Receptor Antagonist (LTRA)
Montelukast - inhibits LTD 4
What is the role of LTC4/LTD4 in Asthma?
- Bronchoconstriction
- Airway Hyperresponsiveness
- Mucosal Edema
- Mucosal Hypersecretion
- Airway smooth muscle hyperplasia
- Increased C-fibres’ Release of Substance P
What is the mechanism of action of Montelukast (Oral)?
Competitive Antagonist against Cysteine Leukotriene (CysLT1) Receptor
What are the uses of Montelukast?
- Prophylaxis and Chronic Treatment of Asthma
- Aspirin Induced Asthma
- Exercise Induced Asthma
What is the efficacy of Montelukast?
Less effective than ICS
- decrease usage of ICS (Steroid Sparing)
What are the side effects of Montelukast?
Psychological Reactions:
Agitation
Hallucinations
Depression
What is Na Cromoglycate?
Mast cell stabiliser
What is the mechanism of action of Na Cromoglycate?
- Inhibits Mast Cell Degranulation induced by IgE mediated cross linking to prevent releast of histamine, prostaglandins and leukotrienes
- Promotes Secretion of Annexin A1 which blocks histamine and eicosanoid release from mast cells
- Blocks inflammatory mediators release from eosinophils, neutrophils and macrophages
What are the uses of Na Cromoglycate?
- Prophylactic Control of Asthma (Inhalation solution only)
- Prophylactic Control of Allergic Rhinitis (Nasal Spray) and Conjunctivitis (ophthalmic preparation)
- Prevents cold, dry air and exercise induced Bronchospasm
What are the uses of Na Cromoglycate?
Less effective than ICS
- decrease usage of ICS (Steroid Sparing)
What are the side effects of Na Cromoglycate?
- Throat Irritation, Mouth Dryness, Coughing (Preventable by first inhaling beta agonist)
- unpleasant and bitter taste
What is Omalizumab?
An Anti IgE mAb (Antibiotic) which targets IgE (effective for basophils)
What is the mechanism of action of Omalizumab?
- Binds to free IgE, decreasing cell-bound IgE + Decreases expression of high-affinity receptors on mast cells, basophils or eosinophils
- Decreases mediator released
- Decreases allergic inflammation
- Prevents exacerbation of asthma and reduces symptoms
What are the uses of Omalizumab?
- Allergic Asthma
2. Allergic Rhinitis
How is Omalizumab taken?
SQ injection every 2-4 weeks
What are Anti-IL5 mAb (Mepolizumab), Anti-IL5R mAb (Benralizumab) and Anti-IL4R mAb (Dupilumab) used for?
Severe Asthma
What are the activities of Beta 2 Agonists?
- Airway smooth muscle relaxation
- Mast cell stabilisation
- Decrease microvascular leakiness
- Increase mucocilliary clearance
What is an example of a non-selective B2 agonist?
Epinephrine (a, B1, B2)
What is a B2 Selective SABA (4-6hrs)?
Salbutamol
What is a B2 Selective LABA (12 hrs)?
Salmeterol (rapid onset)
Formoterol (slow onset)
What is a B2 Selective LABA (24 hrs) for COPD only?
Indacaterol
What is the preferred reliever of choice?
ICS + Formoterol
What provides long term maintenance of asthma (Nocturnal Asthma)
ICS + LABA
When on long term maintenance of asthma (ICS + LABA) what can be used as a reliever?
SABA Salbutamol (As required basis)
What are the side effects of Beta Agonists?
- Fine tremor of skeletal muscles (eg. hand)
- Muscle cramps (eg. Leg)
- Peripheral Vasodilation
- Palpitations and Tachycardia (due to cross reaction with B1 receptors)
- Hypokalemia/Hyperglycemia
What is the black box warning label for LABA?
Tolerance causing Asthma-related death
What is an example of a Methylxanthine?
Theophylline
What is Theophylline used for?
- Adjunct/Extended/Add on therapy when ICS + SABA/LABA still cannot control asthma
- Sustained Release preparations for nocturnal bronchospasm
- improve lung function in COPD
What is the mechanism of action of Theophylline?
- Inhibits Phosphodiesterases –> increase cAMP –> relaxation
- Blocks Adenosine receptor –> relaxation of airway smooth muscle
- Increase Epinephrine Release from Adrenal Medulla –> binds to B2 receptors –> bronchodilation
- Anti-inflammatory effects: mast cells and t cells
- Decrease microvascular leakiness
- Increase contractility of Fatigue Diaphragm in COPD
Which is a more effective bronchodillator? Theophylline or B2 agonists or Muscarinic Antagonists
B2 agonists
What is the dosage form of Theophylline?
100% Oral-SR, IV
What are the side effects of Theophylline?
- Narrow therapeutic range 5-20mg/L - caution for drug drug interactions
- GI: N/V, Anorexia, Abdominal Discomfort
- CNS: Nervousness, Tremor, Anxiety, Headache, Seizures
- CV: Arrhythmias
What is an example of a Short Acting Muscarinic Antagonist (SAMA)
Ipratropium Bromide (Quaternary Amine)
What is the mechanism of action of muscarinic Antagonists?
- Inhibits M3 Receptor-mediated Bronchoconstriction
2. Inhibits parasympathetic impact: Reverse the portion of bronchospasm and mucus secretion induced by vagal nerves
What is the dosage form for muscarinic antagonists?
Inhalation
Poor systemic absorption and does not readily cross BBB
What are the uses are Ipratropium Bromide?
- Adjunct/Extended/Add on therapy when ICS + SABA/LABA still cannot control asthma
- Patients intolerant of B2 Agonists
- More bronchodilator effect in COPD
What is an example of a Long Acting Muscarinic Antagonist (LAMA)
Tiotropium Bromide (Once daily inhalation)
What are the side effects of muscarinic antagonists?
- Unpleasant Taste
- Dry mouth
- Urinary Retention in the Elderly
- Paradoxical Bronchospasm
Why is B2 agonists bronchodilator always used in combination with Inhaled Corticosteroids?
Inhaled corticosteroids upregulates B2 receptor expression in the airway smooth muscle cells