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Drugs affecting the Respiratory Systems Kuntarti, SKp, MBiomed Anatomy & Physiology of respiratory 1. The Upper respiratory tract nares, nasal cavity, pharynx,& larynx 2. The Lower respiratory tract trachea, bronchi, bronchioles, alveoli, & alveolar-capillary membrane Ventilation & Respiration Ventilation is the movement of air from the atmosphere through the upper & lower airways to the alveoli Respiration the process whereby gas exchange occurs at the alveolar-capillary membrane Phases of respiration 1. Ventilation in which oxygen passes through the airways 2. Perfusion in which blood from the pulmonary circulation is adequate at the alveolar-capillary bed 3. Diffusion of gases in which oxygen passes into the capillary bed to be circulated and carbon dioxide leaves the capillary bed & diffuses into the alveoli for ventilatory excretion Lung compliance 1. Connective tissue (collagen & elastin) 2. Surface tension in the alveoli (by surfactant) Control of respiration Chemoreceptors changes of concentration of O2, CO2, H+ *The central chemoreceptors: in the medulla near the respiratory center & cerebrospinal fluid (by: CO2 & pH) * Peripheral chemoreceptors: in the carotid & aortic bodies (by: changes of oxygen levels) Bronchial smooth muscle Contraction constricts the airway * The vagus nerve (parasympathetic nervous system) acetylcholine bronchoconstriction * The sympathetic nervous system epinephrine bronchodilatation Common manifestations of respiratory disease Sneeze - caused by a foreign body or irritant; inflammation - the early stages of a ‘cold’ - requires no medication; a steroidal nasal spray for prophylactic - Sodium cromoglycate for prophylactically in the control of allergic rhinitis by topical inhalation (Hopkins, 1992) Sputum - purulent (by infection); frothy (by pulmonary edema); bloodstained (by haemoptysis); tenacious (by cystic fibrosis or mucous plugging) - Expectorants to liquefy mucus Common manifestations of respiratory disease Noisy breathing - Stridor is a rasping sound heard predominantly in inspiration - a cough that is caused by inflammation of the mucosa of the larynx, trachea, & bronchi, with narrowing of the subglottic area (by virus) - Medication: moist inhalations, nebulized steroids & adrenalin Drugs affecting the Respiratory Systems Drugs for asthma 1. anti-inflammatory agents 2. bronchodilators Drugs for rhinitis, cough, & colds 1. nasal decongestans 2. antihistamines 3. anti-inflammatory agents 4. antitussives 5. Expectorants & mucolytics Asthma common in children & adults characteristic signs: breathlessness, tightness in chest, wheezing, dyspnea, & cough chronic inflammatory disorder of the airway a reaction to allergens symptoms of asthma: combination of inflammation & bronchoconstriction Drugs for asthma 2 main pharmacologic class: 1. Anti-inflammatory agents: glucocorticoids & cromolyn 2. Bronchodilators: beta2 agonists most antiasthmatic drugs can be administered by inhalation, caused: - therapeutic effects are enhanced (by delivering drugs directly to their site of action) - systemic effects are minimized - relief of acute attacks is rapid Bronchodilator & antiasthma Sympathomimetics/Beta2-Adrenergic agonist - Examples: epinephrine, isoproterenol, isoetharine, albuterol, terbutaline, ephedrine - Use/ mechanism of action: treat asthma, bronchitis, & emphysema by stimulating beta2 receptors in bronchial smooth muscle to produce bronchodilatation, & thereby relieve bronchospasm - Adverse effect: CNS: restlessness, anxiety, dizziness,headache, insomnia; Cardiovascular: palpitations, cardiac arrhythmias, tachycardia, hypertension, cerebrovascular accidents, angina; GI: nausea, severe vomiting, diarrhea Sympathomimetics Adverse effect: Skin: local necrosis & tissue sloughing from extravasated intravenous catecholamines Contraindication:cardiovascular diseases, phenochromacytoma, hypertension Precaution: hyperthyroidism, diabetes, & pregnancy Glucocorticoids (steroid) Examples: dexamethasone, betamethasone, prednison Use/mechanism of action: steroids reduce symptoms of asthma by suppressing inflammation (decreased synthesis & release of inflammatory mediators; decreased infiltration & activity of inflammatory cells; decreased edema of the airway mucosa) Adverse effect: inhalation oropharingeal candidiasis & dysphonia (hoarseness & speaking difficulty); oral (in prolonged therapy adrenal suppression, osteoporosis, hyperglycemia, peptic ulcer disease, & suppression of growth (in young patients) Glucocorticoid Contraindication: systemic fungal infections; individuals receiving live-virus vaccines Cautions: pediatric, pregnant & breast feeding woman Cromolyn/ Mast cell stabilizers Examples: Cromolyn, Nedocromyl Use/ mechanism of action: Cromolyn suppresses inflamation by stabilizing the cytoplasmic membrane of mast cells, thereby preventing release of histamine & other mediators. Cromolyn inhibits eosinophils, macrophages & other inflammatory cells Adverse effects: cromolyn is the safest of all antiasthmatic medications, the most common reactions are wheezing, coughing & unpleasent taste Methylxanthines Examples: Theophylline, aminophylline, dyphylline Use/ mechanism of action: theophylline produces bronchodilatation by relaxing smooth muscle of the bronchi, the most probable mechanism is blockade of receptors for adenosine. Adverse effects: theophylline has a narrow therapeutic range, & hence dosage must be carefully controlled; at plasma levels > 20μg/ml : nausea, vomiting, diarrhea, insomnia, restlesness, dysrhythmia & convulsion Anticholinergic/ muscarinic antagonist Examples: atropine, ipatropium bromide (atrovent) Use/ mechanism of action: by blocking muscarinic cholinergic receptors in bronchi, & thereby promotes bronchodilatation Adverse effects: dryness of oropharynx, cough Drugs for rhinitis Rhinitis: an inflammation of the nasal mucous membranes Symptoms: sneezing, rhinorrhea, nasal itching, & nasal congestion Allergic & non-allergic Drugs: (1) nasal decongestants (2) antihistamines (3) intranasal anti- inflammatory Nasal decongestants Examples: phenylephrine, phenylpropanilamine (ppa) Use/ mechanism of action: by stimulating alpha1- adrenergic receptors on smooth muscle of nasal blood vessels vasocontriction shrinkage of swollen membranes nasal drainage; topical administration more rapid & intense than oral administration Adverse effects: rebound congestion; CNS stimulation; cardiovascular effects widespread casoconstriction Contraindication & caution: hypertension & CAD Antihistamines (H1-receptor antagonist) Examples: diphenhydramine, chlorpheniramine, promethazine, azatadine (1st generation), terfenadine, astemizole, loratadine (2nd generation) Use/ mechanism of actions: these agents can relieve sneezing, rhinorrhea, & nasal itching by blocking H1 receptor & thereby preventing the actions histamines at these sites Adverse effects: sedation (1st generation), cardiac dysrytmia, dizzines, nausea, vomiting,constipation, dry mouth Drugs for cough & cold Cough: a complex reflex involving the central & pheripheral nerve systems & muscles of respiration can be initiated by irritation of the bronchial mucosa (+): remove foreign matter & excess secretions from the bronchial tree (-): deprive us of comfort & sleep Common cold: an acute upper respiratory infection of viral origin Symptoms: rhinorrhea, sneezing, cough, sore throat, headache, malaise,& myalgia Combination cold remedias, 2 or more of: 1. nasal decongestants 2. antitussives 3. analgesic 4. antihistamines 5. caffeine Antitussive agents Examples: opioid codeine, hydrocodone; non- opioid dextromethorpan hydrobromide (DMP) Use/ mechanism of action: suppress coughing by altering response threshold of cough center in the medulla or peripherally by inhibiting pulmonary stretch, thus decreasing impulses to the cough center Antitussive agents Adverse effects: - Codeine: impaired alertness or coordination, hypersensitivity, dependence; toxic reactions: euphoria, hyperactivity, nystagmus, uncoordinated movements, stupor, shallow breathing - DMP: drowsiness & GI upset; toxic reaction: miosis, bradycardia, tachycardia, hypotension, narcosis, seizures, circulatory collapse Contraindication: pregnancy, lactation, known hypersensitivity Antitussive agents Precautions: benign prostatic hypertrophy, debilitation, thoracotomy, laparotomy, history of drug abuse Drug interactions: - DMP and MAO (monoamine oxidase) inhibitors: excitation, hyperpyrexia - narcotic/opioid antitussive with MAO inhibitors, alcohol, & other CNS depressants: potentiation of CNS depressive effects Expectorants agents Examples: ammonium chloride, guaifenesin/glyceryl guaiacolate (GG) Use/ mechanism of action:facilitate expulsion of mucus by reducing adhesiveness and surface tension of mucus Precaution:liver and renal insufficiency Adverse effects: - GG: drowsiness, nausea, vomiting Mucolytic agents Examples: bromhexin, ambroxol, acetilcistein, hypertonic saline Use/ mechanism of action: enhance mucolysis by altering molecular composition of mucus, reducing viscosity; ambroxol: stimulate surfactant production of premature infant with respiratory distress syndromes Precaution: gastric ulcer Adverse effects: - bromhexin: nausea, serum transaminase level - acetilcistein: bronchial spasm, nausea, vomiting, stomatitis, haemoptysis Nursing diagnosis 1. Ineffective airway clearance related to mucus accumulation manifested by cough & ronchi 2. Risk for infection related to build up of respiratory secretions 3. Risk for injury related to CNS depression Nursing implementation Administration procedures * Increase fluid intake of client taking expectorant Daily monitoring & measurements * Monitor client taking codeine for signs of respiratory depression Client teaching 1. Explain to client the importance of increasing fluid intake when taking expectorant 2. Encourage patient who is confined to bed and taking expectorant to turn, breathe deeply, & cough every 2 hours 3. Warn client taking a narcotic antitussive not to drink alcohol 4. Caution client that prolonged use of codeine may cause dependence 5. Show client how to use and clean nebulizer for acetylcystein administration Nursing evaluation Client shows: Absence of coughing. Improved ability to cough up mucus. No signs or symptoms of infection (Cardinal signs). No signs of excessive CNS depression.
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