Bronchial Asthma Part 1 PDF

 ILOS  Define bronchial asthma.  Explain different lines of treatment of bronchial asthma.  Explain mechanism of action of drugs used in treatment of bronchial asthma  List adverse effects and precautions of drugs used in treatment of bronchial asthma.  Bronchial asthma...

 ILOS  Define bronchial asthma.  Explain different lines of treatment of bronchial asthma.  Explain mechanism of action of drugs used in treatment of bronchial asthma  List adverse effects and precautions of drugs used in treatment of bronchial asthma.  Bronchial asthma Definition: Is a chronic inflammatory disease of airways characterized by a state of increased responsiveness of trachea and bronchi to various stimuli. Manifested by widespread inflammation and narrowing of the airways that changes in severity either spontaneously or as a result of treatment.  Bronchial asthma Definition: recurrent reversible airway obstruction in response to different stimuli. Asthmatic attack composed of: (cough, wheezing, difficulty in breathing). Pathogenesis of Asthma: General measure: Stop smoking antigen Severe exercise Avoid Stress& emotion Certain drugs e.g Aspirin Chest infection Treat immunotherapy  :Drug treatment β adrenergic agonists Bronchodilators Methylxanthines Anticholinergics Glucocorticoids Leukotrines receptor antagonist Anti-inflammatory Anti IgE monoclonal antibody Mast cell stabilizers : prophylactic Expectorant & mucolytic Ttt of respiratory infection Supportive Sedative & tranquilizers therapy O2 therapy & fluid therapy desensitization Bronchodilators  β2 adrenoceptor agonist Classification: Short acting 4-6h e.g. : salbutamol Selective less adverse effects long acting 12 h β2 agonist e.g. : salmeterol Non selective e.g. : adrenaline, isoprenaline, ephedrine  Beta-2 agonist Dynamics: ↑cAMP⇛relaxation of smooth muscle ↑mucocilliary transport of secretion ↓ release of bronchospasm mediators ↓micro vascular permeability  Selective β2 agonists Salbutamol Synthetic sympathomimetic catecholamine Kinetics: oral,parenteral,inhalation pass BBB Action:  Bronchodilatation  ↓bronchial secretion  Stabilize mast cell  Uterine relaxant Salmeterol, formeterol: long acting used for prophylaxis Uses of selective β2 agonist:  Bronchial asthma  Uterine relaxant:ritodrine  Methylxanthine Theophylline, theobromine,caffeine Kinetics: oral, sustained release, I.V,inhalation,rectal slow, Pass in all tissue compartment , cross placenta, milk Narrow therapeutic margin Dynamics: 1. ↓PDE enzyme⇛↑cAMP⇛smooth muscle relaxation 2. ≠ adenosine receptors 3. Inhibit antigen histamine release 4. ↑catecholamine release from adrenal medulla↓COMT  Adverse effects: CVS: Tachycardia, arrhythmia. CNS: Convulsions, nervousness. GIT: Heart burn, vomiting, abdominal pain, peptic ulcer. Precautions of theophylline 1- Intravenous injection should be slow otherwise cardiac arrhythmias, hypotension, and cardiac arrest occur. 2- Lower infusion rates should be used in patients with heart failure, liver dysfunction, and in the elderly. 3- The loading dose should be reduced or omitted if the patient has received theophylline within the past 24 hours  Precautions of theophylline 4-Oral preparations should be given with food to avoid gastric irritation. 5-Theophylline serum level should be measured 24 hours after starting treatment and then at regular intervals of 6-12 months thereafter.  Anticholinergic agents Atropine is no longer used in bronchial asthma although it is bronchodilator? Ipratropium bromide Kinetics: Quaternary amine –produce fewer side effects [inhalation] Mode of action : prevent bronchoconstriction mediated via vagus Actions: More selective bronchodilator effect with lesser action on sputum viscosity. It has a slower onset (1-2 hr), weak effects on CNS, heart, blood pressure, bladder or IOP. Uses: COPD,chronic bronchitis, emphysema Psychogenic asthma and asthma induced by B2 blocker Side effects?  leukotrienes antagonist Ziluton: oral, selectively inhibit 5-lipoxygenase, (inhibit LT synthesis) Zafirlukast & montelukast: oral ,antagonist to leukotriene receptors. Both are effective in exercise, antigen and aspirin induced bronchial asthma.  Anti IgE monoclonal antibody It is anti-IgE monoclonal antibody ;inhibits mast cell degranulation. It may also inhibit IgE synthesis by B lymphocytes. Repeated intravenous or subcutaneous injection of anti- IgE MAb lessens asthma severity and reduces the corticosteroid requirement in patients with moderate to severe asthma,