Question | Answer |
List the asthma controlling drugs & examples if applicable(4) | Usually anti-inflammatory
Corticosteroids: Fluticasone, ciclesonide.
Anti IgE antibodies.
Leukotriene receptor antagonist: Zileuton, Zafirlukast
Cromolyn: Cromolyn Na |
Corticosteroids: uses | 1st line prophylactic asthma therapy. Is also used for nocturnal asthma. |
Corticosteroids: mode of action | Enters cell after unbinding from corticosteroid-binding globulin, binds to steroid receptors in cytoplasm. There will then be formation of a protein that inhibits phospholipase A2 which then inhibits arachidonic acid pdtn. |
Corticosteroids: effects | Decreases airway hyper-responsiveness within 4 weeks. (anti-inflammation proportional to anti asthma). prevents airway remodelling and decreases need for B-blockers + death. |
Corticosteroids: toxicity & example | Cough, throat irritation, oropharyngeal candidiasis (due to lowered immune response), adrenal suppression. Example is fluticasone |
Anti IgE antibodies: everything | Used in allergic reaction (rhinitis and asthma). Binds to Fc receptor on IgE antibody, thus preventing it from causing mast cell degranulation + histamine release. However, it is humanized Ab & can cause allergy. |
Leukotriene receptor antagonist: mode of action and example | Zileuton inhibits 5-lipoxygenase activity which prevents leukotriene production, zafirlukast inhibits leukotriene activity as a CysLT1 receptor antagonist. |
Leukotriene receptor antagonist: uses, effects and toxicity | Prophylaxis for chronic asthma, aspirin (explain) and exercise induced asthma. Not as effective as corticosteroids so not as used, but also reduces frequency of asthma, use of B2 agonists and death. Minimal side effects. |
Cromolyn: uses | Weakest and thus commonly used in paediatrics for prophylactic control of asthma and allergic rhinitis. |
Cromolyn: effects | Decreases overall bronchial hyper-reactivity in 4 weeks. Also decreases need for B-blockers and brochodilator therapy. |
Cromolyn: toxicity | Can cause throat irritation, mouth dryness and coughing. This can be prevented by first inhaling B2 agonists. |
Cromolyn: mode of action | Inhibits mast cell degranulation induced by IgE through alteration of delayed chloride channel, preventing cellular activation. |
Bronchodilating drugs that relieve asthma attacks (3) | B2 agonists: Isoproterenol, Salbutamol, Salmeterol.
Anti-muscarinics: Tiotropium bromide.
Methylxanthines:Theophylline. |
B2 agonists: types and examples | There are non selective ones that work for 1-3 hours: isoproterenol, B1 &B2. SABA, 3-6h: Salbutamol. LABA, 12h: Salmeterol. |
B2 agonists: mode of action | They activate G-protein coupled receptors -> adenylyl cyclase -> cAMP -> increase K+ conductance & reduced MLCK activity -> bronchodilation. |
B2 agonists: uses | SABA is used on an "as required" basis, not to be used for regular intake. LABA is used for exercise induced asthma and for long-term maintenance of asthma. ULABA is used for COPD treatment. |
B2 agonists: toxicity | MPPHHTT: Muscle cramps, peripheral vasodilation, palpitations, hypokalemia, hyperglycemia and tolerance. |
Methylxanthines: mode of action & examples | Inhibits phosphodiesterase that ultimately results in reduced leukotriene production -> anti- inflammatory. Also adenosine receptor antagonists, which increases smooth muscle relaxation and thus bronchodilation. eg. Theophylline. |
Methylxanthines: effects | Increases release of adrenaline from adrenal medulla. Anti-inflammatory and relaxes bronchioles. Weaker than B2-agonists |
Methylxanthines: uses | Sustained release preparations for nocturnal bronchospasms. |
Methylxanthines: toxicity | Severe potential for drug interactions AND has narrow therapeutic range. Many side effects such as nausea, vomiting, tremor, anxiety, arrythmias, headaches. Drug is however still used in elderly patients who have been on it long term. |
Anti-muscarinics: uses and example | supplementary to B2 agonist and steroids. also used in patients intolerant to B2 agonists and has a bigger bronchodilator effect in COPD. Example is Triotropium bromide |
Anti-muscarinics: mode of action | Inhibit M3 receptor mediated bronchoconstriction. M3 receptors are only expressed in lung and so it is very specific to airways. Less effective as it only targets one receptor. |
Anti-muscarinics: toxicity | Dry mouth, bitter, paradoxical bronchospasms. |