Supplies oxygen for the body Provides protection against inhaled organisms Controlled by chemoreceptors and mechanical receptors

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1 1 Unit 8 Respiratory Agents 2 Respiratory System Supplies oxygen for the body Provides protection against inhaled organisms Controlled by chemoreceptors and mechanical receptors 3 Nervous System Influence on Respiration Sympathetic Stimulation Smooth muscle contraction Bronchoconstriction Decrease Respiratory rate and depth Parasympathetic (Cholinergic) Smooth muscle relaxation Bronchodilation Increase respiratory rate and depth 4 The respiratory system and the process of gas exchange 5 Respiratory System Upper respiratory tract (URT): Nose, nasal cavity, pharynx, paranasal sinuses. Function Warm, humidify, and clean the air Traps and removes particulate matter & pathogens 6 Respiratory System Lower respiratory tract (LRT): Lungs and associated structures Perfusion - blood flow through the lung Ventilation - process of moving air in and out of lungs 7 Inhalation Route of Drug Administration Rapid and efficient mechanism for delivering drugs Almost instantaneous onset of action for inhaled substances. Medications are delivered directly to their sites of action by aerosol therapy 8 Drug Delivery An aerosol is a suspension of very small liquid droplets or fine solid particles suspended in a gas 1

2 9 Drug Delivery Nebulizers- small machines that vaporize a liquid drug into fine mist to inhaled, often using facemask. Dry powder inhaler (DPI) - small device activated by the process of inhalation to deliver a fine powder directly to the bronchial tree. Turbohalers and rotahalers are types of DPIs. Metered-dose inhalers (MDIs) are a third type of device commonly used to deliver respiratory medicines Figure 28.2 Devices used to deliver respiratory drugs Figure 28.2 (continued) Devices used to deliver respiratory drugs Figure 28.2 (continued) Devices used to deliver respiratory drugs 13 Allergic rhinitis Characterized by sneezing, watery eyes, and nasal congestion 14 Figure 28.3 Drugs used to treat respiratory disorders 15 Antihistamines Widely used to treat allergic rhinitis and other minor allergies Table 28.1 (continued) H1-Receptor Blockers (Antihistamines) Intranasal Glucocorticoids Drug of choice to treat allergic rhinitis Must be applied consistently Decrease the secretion of inflammatory mediators Reduce tissue edema Cause a mild vasoconstriction Can take 2-3 weeks of therapy before optimum benefits reached 20 Glucocorticoids When delivered by oral inhalation (not intranasal) some of these medications are also used to treat asthma Decongestants Used to reduce nasal congestion caused by allergic rhinitis and the common cold Sympathomimetics: agents that activate sympathetic nervous system Oral and intranasal preparations are available 2

3 23 Decongestants Rebound congestion Prolonged use causes hypersecretion of mucus and worsened nasal congestion once the drug effects wear off. Rebound effect sometimes leads to a cycle of increased drug use as the condition worsens Should be used for no longer than 3 to 5 days Antitussives and expectorants Antitussives and expectorants are used to treat symptoms of the common cold. 26 Antitussives Opioids Act by raising the cough threshold in the cough center decrease both the frequency and intensity of cough. Non-Opiods Dextromethorphan - Chemically similar to the opioids acts on the CNS to raise the cough threshold. 27 Antitussives Benzonatate (Tessalon) -has local anesthetic-like effect on stretch receptors in the lung, which essentially interrupts the cough message. 28 Expectorants Drugs that reduce the thickness or viscosity of bronchial secretions Stimulate mucus flow, which thins bronchial secretions allowing them to be removed with less forceful coughing. Guaifenesin (Mucinex) 29 Mucolytics Directly loosens thick, viscous bronchial secretions by breaking down the chemical structure of mucous molecules 30 Mucolytics Acetylcysteine (Mucomyst) Delivered by inhalation route and is not available OTC. Used in pts who have cystic fibrosis or other diseases producing large amounts of thick bronchial secretions Also given as a 5% oral solution for acetaminophen overdose. 31 Asthma Asthma is a chronic inflammatory disease characterized by bronchospasm. 32 Asthma 3

4 Chronic inflammation occurs when potent mediators of the immune and inflammatory responses are released by mast cells lining the bronchial passageways. Increased mucus secretion, which narrows the airways and makes breathing more difficult. 33 Asthma Symptoms Evening cough, dyspnea, chest tightness, wheezing Bronchoconstriction or bronchospasm Status asthmaticus Severe, prolonged form of asthma, unresponsive to drug treatment, may lead to respiratory failure 34 Changes in bronchioles during an asthma attack: (a) normal bronchiole, (b) constricted bronchiole in asthma attack 35 Drug classes used in the pharmacotherapy of asthma Beta-adrenergic agents Most effective drugs for relieving acute bronchospasm 38 Beta-Adrenergic Agents Short-acting beta agents Most frequently prescribed drugs for aborting or terminating acute asthma attack Begin to act within minutes Last only 2-6 hours 39 Beta-Adrenergic Agents Long-acting beta agents Take 20 to 60 minutes to act Not used to terminate bronchospasm Used in combination with inhaled corticosteroids for prophylaxis of severe, persistent asthma Bronchodilators (continued) 42 Glucocorticoids Most effective drugs for the long-term prophylaxis of asthma. 43 Glucocorticoids Not for immediate relief Must be used on a daily schedule 4

5 Symptoms improve 1-2 weeks 4-8 weeks for maximum benefit Suppress inflammation Mucus production and edema diminished reducing airway obstruction Mast cell stabilizers and leukotriene modifiers Alternative anti-inflammatory drugs for the prophylaxis of asthma. 46 Mast Cell Inhibitors Mast Cell Inhibitors Inhibit the release of histamine from mast cells. Safe alternative to the glucocorticoids 47 Leukotriene Modifiers Leukotriene Modifiers Reduce inflammation, ease bronchoconstriction. Modify action of leukotrienes, which are mediators of the inflammatory response Used for management of persistent asthma not controlled with inhaled glucocorticoids or short-acting beta agents. 48 Anti-Inflammatory Drugs for Asthma (continued) 49 Distinguish the classes of drugs that prevent asthma attacks from those that can terminate an attack in progress. Name at least one drug in each class. 50 COPD Chronic obstructive pulmonary disease is a progressive disorder treated with multiple drugs. 51 COPD Receive a number of pulmonary drugs for symptomatic relief Goals of pharmacotherapy Treat infections To control cough and relieve bronchospasm Drugs Used Bronchodilators, beta2-agents, or inhaled glucocorticoids, mucolytics, expectorants, oxygen therapy 52 Review What is the difference between ventilation and perfusion? Name the three types of devices used to deliver drugs by the inhalation route. What are the differences among them? Why are the antihistamines most effective if given before inflammation occurs? 5

6 53 Review The sympathomimetics are the most effective drugs for relieving nasal congestion, but physicians often prefer to prescribe antihistamines or intranasal glucocorticoids. Why? 6