antiasthmatic drugs ,mechanism of action, adverse effects

Adverse effects and moa

1. DRUGS USED IN ASTHMA [Anti-asthmatic drugs] Asthma is an Chronic inflammatory disorder of the airways in which many cells and cellular elements play a role . this inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning . Morbidity and mortality highly correlated with poverty, urban air quality, indoor allergens, lack of patient education, and inadequate medical care About 5000 deaths annually.

2. Allergens Dust mites, mold spores, pollen, indoor and outdoor pollutants, irritants (smoke, perfumes, cleaning agents). Pharmacologic agents; ASA[acetyl salicylic acid], beta-blockers. Physical triggers (exercise, cold air, distilled water, and sulfur dioxide).  Diseases; viral and bacterial URI[upper respiratory infection ], rhinitis

3. CLASSIFICATION 1.BRONCHODILATORS A.Sympathomimetics Short Acting: Salbutamol, Terbutaline Long Acting: Formeterol , Salmetrol , Bambuterol Mechanism of Action - Beta-2 adrenergic agonist, when administered binds beta 2 receptors  Stimulation of adenylate cyclase  Increase cAMP  Bronchodilation and decreased muscular tone.

4. B.Methylxanthine : Aminophylline, Theophylline Mechanism of Action 1. Inhibit Phosphodiestrase Enzyme (which catalyzes breakdown of cAMP ). Increase cAMP Dephosphorylation of MLC Bronchodilation 2. Increased intracellular calcium 3.Decrease contractility of bronchiolar smooth muscles. C . Anticholinergics : Ipratropium, Oxytropiu , Tiotropium Mechanism of Action  Blockade of muscarinic receptors present in bronchi and bronchioles  Decrease mucus viscosity  Increase mucociliary clearance

5. 2.Leukotriene Receptor Antagonists  Montelukast – oral  Zafirlukast – (Cingular) oral administration for control of asthma Leukotrines are products of arachidonic acid metabolism. They are released at the site of inflammation producing bronchoconstriction having contributory effect to inflammation and bronchoconstriction. Mechanism of Action Montelukast and Zafirlukast are competitive antagonists .  Inhibits cysteinlyl leukotriene Cys LT1 receptor relieving bronchospasm and bronchoconstriction.  Inhibit physiologic actions  One drug blocks synthesis of 5 lipooxygenase and is hepatotoxic Zileuton . Half like is 2.5 hours

6. 3.Mast Cell Stabilizers Na chromoglycate inhalation Nedocromil Ketotifen - (5HT action) oral Mechanism of Action Stabilize mast cells membrane and inhibit release of chemical mediators Depress exaggerated neuronal reflexes triggered by stimulation of irritant receptors. Depress axonal reflexes which release inflammatory neuropeptides . Inhibit release of cytokines from T-CELLS.

7. 4.Corticosteroids Hydrocortisone I/V Prednisolone oral Betamethosone Beclomethasone inhalation Budesonide Flucitasone Mechanism of Action Anti inflammatory action Decrease mucosal oedema, mucus secretion and reduce capillary permeability Stabilize mast cells Block immune response, decrease antibody formation Antagonise histaminergic and cholinergic responses Enhance beta-2 adrenoceptor responsiveness to agonists ( Catecholamines )

8. 5.Monoclonal Antibodies : Omalizumab They bind to IgE antibodies present on mast cells. If administered I/V or subcutaneously, humanized monoclonal antibodies decrease levels of IgE antibodies, decreasing tendency of severe asthma, in both phases (immediate/delayed)

9. ADVERSE EFFECTS Some side effects of medications have been noted to include tremor, increased nervousness and insomnia in children, nausea, fever, bronchospasm, vomiting, headache, pain, dizziness, cough, allergic reaction, dry mouth, sweating, chills, and dyspepsia.