NUR 312 Principles of Pharmacology PDF

NUR 312 Principles of Pharmacology Drugs Acting on the Respiratory System Chapters 53-55 LaNassa Moore, MSN, RN Biblical Foundations John 15:5 King James Version I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without m...

NUR 312 Principles of Pharmacology Drugs Acting on the Respiratory System Chapters 53-55 LaNassa Moore, MSN, RN Biblical Foundations John 15:5 King James Version I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. Chapter 53 Introduction to the Respiratory System Respiratory System Brings oxygen into the body Allows for the exchange of gases Leads to the expulsion of carbon dioxide and other waste products  Primarily involved in ventilation. Change quality of atmospheric air. Nasal hairs catch and filter foreign substances. Mucociliary escalator or blanket Conducting Goblet cells produce mucus that traps foreign substances. Airways Cilia move the mucus and trapped substances toward the throat for swallowing. Pairs of sinuses open into nasal cavity; mucus produced in sinuses drains into nasal cavity and into throat.  Air moves from nasal cavity into pharynx and larynx. Air proceeds to trachea, the main conducting airway into Conducting the lungs. Trachea divides into bronchi. Airways cont. Further divide into smaller and smaller branches Cough and Sneeze Reflexes Walls of the trachea and conducting bronchi are highly sensitive to irritation. When receptors in the walls are stimulated, CNS reflex is initiated. Cough causes air to be pushed through the bronchial tree under tremendous pressure, cleaning out any foreign irritant. Sneeze reflex is similar. Initiated by receptors in nasal cavity Respiratory Airways Layers of bronchial Alveoli Lungs tubes Respiratory sacs at end of Bronchial tree bronchioles Alveoli Smallest unit of lungs Blood supply Functional units where gas Blood for pulmonary perfusion exchange occurs Elastic tissue Left lung: two lobes Right lung: three lobes Ventilation Controlled by CNS Inspiratory muscles stimulated by the respiratory center includes neurons in pons and medulla. Rate and/or depth of breathing can be increased quickly if chemoreceptors note higher acid or carbon dioxide levels. Stretch and irritant receptors trigger expiration. Voluntary control of breathing. Vagus nerve stimulates diaphragm contraction and inspiration. Sympathetic stimulation allows freer flow of air. Respiratory Tract Infections Common cold Caused by number of viruses that invade upper respiratory tract tissues Initiates release of histamine, prostaglandins Causes inflammatory response Sinus pain, nasal congestion, runny nose, sneezing watery eyes, scratchy throat, headache Seasonal rhinitis Inflammation of nasal cavity Upper airways respond to specific antigen Vigorous inflammatory response Nasal congestion, sneezing, stuffiness, watery eyes Respiratory Tract Infections cont. Sinusitis Epithelial lining of sinus cavities becomes inflamed. Causes severe pain due to pressure against bone If left untreated, microorganisms can travel to brain tissue or affect eyesight. Pharyngitis, laryngitis, and bronchitis Inflammation of the structure Caused by either viral or bacterial infection Pharyngitis and laryngitis frequently seen with influenza Bronchitis Acute: most often viral infection Chronic: irritation from noxious stimuli + recurrent infections Respiratory Tract Infections cont. Pneumonia Inflammation of the lungs Caused by bacterial or viral invasion or aspiration of foreign substances Localized swelling, engorgement, exudation of protective sera Difficulty breathing and fatigue, fever, noisy breath sounds, poor oxygenation Tuberculosis Discussed in Chapter 9 Cough (often bloody tinged), fatigue, shortness of breath, fever, chills, weight loss, night sweats Ventilation and Gas Exchange Disorders Atelectasis Incomplete expansion of alveoli Result of outside pressure against the alveoli or pleural effusion Commonly a result of airway blockage Crackles, dyspnea, fever, cough, hypoxia, changes in chest wall movement Bronchiectasis Chronic disease Dilation of bronchial tree and chronic infection and inflammation of bronchial passages There is often an underlying medical condition that makes patient more susceptible to infections. Fever; malaise; myalgia; arthralgia; purulent, productive cough  Asthma Characterized by reversible bronchospasm, inflammation, hyperactive airways Chronic inflammatory response: cytokine-mediated Ventilation inflammation, mucous production, edema contributing to obstruction Wheezing, shortness of breath, chest tightness, and/or and Gas COPD cough Exchange Progressive, not completely reversible chronic obstruction of airways Disorders cont. Often related to cigarette smoking Emphysema and chronic bronchitis Airflow obstruction on expiration, increased inflation of lungs, poor gas exchange  Cystic fibrosis Hereditary disease involving epithelial linings of respiratory, gastrointestinal, and reproductive tracts Accumulation of copious amounts of thick secretions in the lungs Obstruct airways, lead to recurrent infections and potential destruction Ventilation of lung tissue Respiratory distress syndrome and Gas Causes obstruction at alveolar level Frequently seen in premature infants delivered before their lungs have fully developed and while surfactant levels are still very low Exchange Decreased gas exchange, low oxygen levels, generalized distress throughout body Acute respiratory distress syndrome Disorders cont. Characterized by progressive loss of lung compliance and increasing hypoxia Typically results from severe insult to the body Extensive epithelial cell damage and increased permeability in alveolar– capillary membrane  Drugs Used to Treat Upper Respiratory Infections Antitussives Chapter 54 Block the cough reflex Decongestants Drugs Acting Decrease the blood flow to the upper respiratory tract and decrease the production of secretions on the Upper Antihistamines Block the release or action of histamine, a chemical that increases Respiratory secretions and narrows airways Expectorants Increase productive cough to clear airways Tract Mucolytics Increase or liquefy respiratory secretions to aid in clearing of airways  Purpose: Block the cough reflex; Treat uncomfortable, unproductive cough Pharmacokinetics Rapidly absorbed, metabolized in the liver, excreted in the urine, Cross placenta, enter human milk Contraindications Patients who need to cough to maintain the airway Antitussives Head injury or impaired CNS Pregnancy and lactation Key Drugs: Codeine: Narcotic antitussive used for treating unproductive coughs but has the potential for addiction. Dextromethorphan: Non-narcotic alternative to codeine for suppressing cough without the risk of dependence.  Cautions Asthma or emphysema Hypersensitivity Codeine, hydrocodone: history of narcotic addiction Adverse effects Antitussives Traditional Drying effect on mucous membranes cont. CNS adverse effects Locally acting GI upset Drug–drug interactions MAOIs Decongestants Purpose: Reduce nasal congestion by shrinking blood vessels (vasoconstriction) in the nasal passages. Relieves discomfort of nasal congestion associated with the common cold, sinusitis, and allergic rhinitis Pharmacokinetics Onset of action almost immediate (topical) Not generally absorbed systemically Any portion absorbed is metabolized in the liver; excreted in the urine Key Drugs: Pseudoephedrine and phenylephrine: Commonly found in oral decongestants – reduces swelling in nasal passages and improves airflow Oxymetazoline: Topical nasal decongestant that quickly relieves congestion but may cause rebound congestion with prolonged use.  Cautions Lesion or erosion in the mucous membranes (topical) Any condition that might be exacerbated by sympathetic activity Pregnancy or lactation Decongestants Adverse effects (Topical and Oral) Local stinging and burning Rebound congestion cont. Sympathomimetic effects Drug–drug interactions Other drugs that affect the sympathetic nervous system Steroid Nasal Decongestants Beclomethasone (Beconase AQ and others) Budesonide (Rhinocort) Flunisolide (generic) Fluticasone (Flonase Allergy Relief) Triamcinolone (Nasacort Allergy 24 Hour)  Therapeutic actions Exact mechanism of action unknown Antiinflammatory action results from direct local Steroid Nasal effect blocking reactions responsible for inflammatory response Decongestant Indications Allergic rhinitis cont. Relieve inflammation after removal of nasal polyps First-line medication for nasal congestion  Pharmacokinetics May require 1 week to cause any changes Not generally absorbed systemically If they were, would have same pharmacokinetics as other steroids Contraindications Acute infection Steroid Nasal Cautions Active infection Decongestant Avoid exposure to airborne infections Pregnancy and lactation cont. Adverse effects Local burning, irritation, stinging, dryness of the mucosa, and headache Suppression of healing can occur in a patient who has had nasal surgery or trauma Drug–drug interactions Concurrent nasal medications should not be administered without consulting provider Antihistamines Purpose: Block histamine to reduce symptoms of allergies, such as sneezing and runny nose. Anticholinergic and antipruritic effects Relief of symptoms associated with seasonal and perennial allergic rhinitis, allergic conjunctivitis, uncomplicated urticaria, and angioedema Allergic reactions to blood or blood products, discomfort associated with dermographism, adjunctive therapy in anaphylactic reactions See Table 54.3 Choice depends on the patient’s reaction to the drug Often misused to treat colds and influenza Key Drugs: Cetirizine (Zyrtec): Second-generation antihistamine that causes less sedation. Loratadine (Claritin): Second-generation antihistamine that does not cause drowsiness.  Pharmacokinetics Well absorbed orally Metabolized in the liver; excreted in urine and feces Cross placenta and enter human milk Contraindications Pregnancy and lactation Cautions Antihistamines Renal or hepatic impairment cont. First generation: History of arrhythmias or prolonged QT intervals Adverse effects Drowsiness and sedation Anticholinergic effects Drug–drug interactions Vary based on the drug Expectorants Purpose: Help loosen mucus to make coughing more productive. Relief of symptoms of respiratory conditions Available in many OTC combination preparations. Key Drug: Guaifenesin (Mucinex): Makes coughing more effective at clearing mucus from the airways  Pharmacokinetics Rapidly absorbed Sites of metabolism and excretion not reported Pharmacokinetics Rapidly absorbed Sites of metabolism and excretion not reported Expectorants Adverse effects GI symptoms cont. Headache, dizziness, or both Prolonged use may result in masking symptoms of a serious underlying disorder Drug–drug interactions No known significant interactions Caution patients there may be interactions with other medications in OTC combinations Mucolytics Purpose: Break down mucus to help clear respiratory secretions. Indications Liquefaction and clearing of secretions Treatment of atelectasis from thick mucous secretions as in CF Key Drugs: Acetylcysteine: Thins and loosens mucus, often used in cases like cystic fibrosis or COPD Dornase alfa: Used specifically in cystic fibrosis to reduce the viscosity of mucus.  Pharmacokinetics Acetylcysteine: metabolized in liver; excreted somewhat in urine Dornase alfa: metabolized by proteases Contraindications History of hypersensitivity reactions Cautions Asthma Mucolytics Pregnancy and lactation Adverse effects cont. GI upset Stomatitis Rhinorrhea Bronchospasm Rash Drug–drug interactions None known Use of Upper Respiratory Tract Agents Across the Lifespan Sites of Action of Drugs Working on the Upper Respiratory Tract Chapter 55 Drugs Acting on the Lower Respiratory Tract Pulmonary Obstructive Diseases Asthma – Causes rapid swelling of the inner lining of the airways and a narrowing of the conducting tubes. Chronic Obstructive Pulmonary Disease (COPD) – Most often caused by chronic exposure to irritants that cause chronic inflammation and swelling in the airway; Muscular and cilial action is lost. Personalized treatment plans with medication and lifestyle changes. Pulmonary Obstructive Diseases cont. Respiratory distress syndrome Causes obstruction at the alveolar level Seen in neonates Obstruction related to lack of the lipoprotein surfactant Adult respiratory distress syndrome Characterized by progressive loss of lung compliance and increasing hypoxia Occurs as a result of a severe insult to the body Use of Lower Respiratory Tract Agents Across the Lifespan Bronchodilators Used to facilitate respiration by dilating the airways Helpful in symptomatic relief or prevention of bronchial asthma and for bronchospasm associated with COPD Xanthines – drugs that have a direct effect on the smooth muscle of the respiratory tract (naturally occurring substances – caffeine and theophylline) Sympathomimetics – drugs that mimic the effects of the sympathetic nervous system Anticholinergics – drugs that block the action of a chemical called acetylcholine in the body. Blocking this chemical helps relax the muscles around the airways, making it easier to breathe.  Sympathomimetics – Mimic effects of the sympathetic nervous system Dilate bronchi; Increase rate and depth of respiration Drugs: Albuterol (Proventil HFA and others) Salmeterol (Serevent) Bronchodilators cont. Short-acting beta agonists (SABAs) – Emergency use Long-acting beta agonists (LABAs) – Chronic management Pharmacokinetics Rapidly distributed Transformed in the liver to metabolites that are excreted in the urine Inhaled Steroids Effective treatment for prevention and treatment of inflammation Prevention and treatment of asthma Drug of choice depends on patient response Drugs: Fluticasone (Flovent Diskus, Flovent HFA) Budesonide (Pulmicort Respules, Pulmicort Flexhaler)  Pharmacokinetics Rapidly absorbed from the respiratory tract Metabolized mostly within the liver; excreted in the urine Glucocorticoids cross placenta and enter human milk Contraindications Not for emergency use Pregnancy or lactation Inhaled Cautions Active infection of respiratory system Steroids cont. Adverse effects Usually fewer adverse effects when inhaled Sore throat, hoarseness, coughing, dry mouth Pharyngeal and laryngeal fungal infections Long-term use: glaucoma, cataracts, decreased bone mineral density Drug–drug interactions None known Leukotriene Receptor Antagonists Developed to act more specifically at the site of the problem associated with asthma Drug Montelukast (Singulair) Add-on therapy for asthma and allergy management when inhaled steroids alone are insufficient. Contraindications Not indicated for treatment of acute asthma attacks Cautions Pregnancy and lactation  Adverse effects Upper respiratory infection, pharyngitis, cough, Leukotriene headache, dizziness, nausea, diarrhea, abdominal pain, elevated liver enzyme concentrations, vomiting, Receptor generalized pain, fever, myalgia. Serious neuropsychiatric events have been reported. Antagonists Drug–drug interactions Warfarin, theophylline, phenytoin, aspirin, others. cont. Check for interactions before administering the drug. Anticholinergics Not as fast acting as sympathomimetics Can provide maintenance treatment with fewer side effects Drugs Ipratropium (Atrovent) Tiotropium (Spiriva) Therapeutic actions Block or antagonize action of acetylcholine at vagal-mediated receptor sites Relaxation of smooth muscle in bronchi Indications Treatment of bronchospasm in patients with COPD  Pharmacokinetics When inhaled, most is not absorbed Metabolism, excretion, and half-lives vary Most are partially excreted unchanged in urine Contraindications Known allergy Cautions Any condition that would be aggravated by the anticholinergic or Anticholinergics cont. atropine-like effects of the drug Pregnancy and lactation Adverse effects Local effects Anticholinergic effects if absorbed systematically Drug–drug interactions Other anticholinergics Xanthines Come from a variety of natural sources Were once main treatments for asthma and bronchospasm Relatively narrow margin of safety; no longer first choice Potential for toxicity Reserved for cases where other treatments fail. Drugs Caffeine (Cafcit, Caffedrine, others) Aminophylline (generic) Theophylline (Elixophyllin, Theo-24, Theochron)  Therapeutic actions Direct effect on the smooth muscles of the respiratory tract, both in the bronchi and in the blood vessels Indications Treatment of COPD and bronchospasm; asthma Pharmacokinetics Rapidly absorbed from GI tract Metabolized in the liver; excreted in the urine Xanthines Cross placenta and enter human milk Contraindications cont. GI problems, coronary disease, respiratory dysfunction, renal or hepatic disease, alcoholism, or hyperthyroidism Cautions Pregnancy and lactation Adverse effects Theophylline: related to levels in the blood Risk increases with levels higher than 20 mcg/mL Drug–drug interactions Many drugs interact with xanthines Substances in cigarettes