Drugs Affecting the Respiratory System PDF

Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology The Respiratory System Instructor, Nursing Pharmacology ANATOMY AND PHYSIOLOGY EXPECTORANTS Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology EXPECTORANTS  increase prod...

Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology The Respiratory System Instructor, Nursing Pharmacology ANATOMY AND PHYSIOLOGY EXPECTORANTS Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology EXPECTORANTS  increase productive cough to clear the airways.  They liquefy lower respiratory tract secretions, reducing the viscosity of these secretions and making it easier to cough them up.  Expectorants are available in many OTC preparations, making them widely available to the patient without advice from a health care  EXPECTORANTS Drugs Affecting the Respiratory System enhances output of respiratory tract fluids by reducing adhesiveness & surface tension of these fluids → easier movement, less viscous → more productive cough & ↓ frequency of coughing Guaifenesin – most popular expectorant Instructor, Nursing Pharmacology COMMON DRUGS Guaifenesin (Mucinex) INDICATION Symptomatic relief of respiratory conditions characterized by a dry, nonproductive cough. CONTRAINDICATION Allergy. This drug should not be used in patients with a known allergy to the drug to prevent hypersensitivity reactions. Pregnancy or lactation. This drug should be used with caution in pregnancy and lactation because of the potential adverse effects on the fetus or baby. Cough. This drug should not be used with persistent coughs, which could be indicative of an underlying medical problem. MECHANISM OF ACTION Enhances the output of respiratory tract fluids by reducing the adhesiveness and surface tension of these fluids, allowing easier movement of the less viscous secretions. PHARMACOKINETICS SIDE EFFECTS  GI: Nausea, vomiting, anorexia.  CNS: Headache, dizziness.  Underlying cough: The most important consideration in the use of these drugs is discovering the cause of the underlying cough; prolonged use of the OTC preparations could result in the masking of important symptoms of a serious underlying disorder.  Respiratory: Rhinorrhea, bronchospasm.  Skin: Rash.  MUCOLYTICS Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology MUCOLYTICS increase or liquefy respiratory secretions to aid the clearing of the airways in high-risk respiratory patients who are coughing up thick, tenacious secretions. Patients may be suffering from conditions such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, pneumonia, or tuberculosis. COMMON DRUGS acetylcysteine (Mucomyst) dornase alfa (Pulmozyme) INDICATION  Liquefaction of secretions in high-risk respiratory patients who have difficulty moving secretions including postoperative patients (e.g., patients with tracheostomies to facilitate airway clearance and suctioning).  Clearing of secretions for diagnostic tests (e.g., diagnostic bronchoscopy).  Used orally to protect the liver from acetaminophen toxicity.  Treatment of atelectasis from thick mucus secretions. CONTRAINDICATION Medical conditions. Caution should be used in cases of acute bronchospams, peptic ulcer, and esophageal varices because the increased secretions could aggravate the problem. MECHANISM OF ACTION  Protect liver cells from being damaged during episodes of acetaminophen toxicity because it normalizes hepatic glutathione levels and binds with a reactive hepatotoxic metabolite of acetaminophen.  Affects the muco-proteins in the respiratory secretions by splitting apart disulfide bonds that are responsible for holding the mucus material together.  The result is a decrease in the tenacity and viscosity of the secretions.  Dornase alfa is a mucolytic prepared by recombinant DNA techniques that selectively break down respiratory tract mucus by separating extracellular DNA from proteins. PHARMACOKINETICS SIDE EFFECTS  GI: Nausea, vomiting, anorexia.  CNS: Headache, dizziness.  Underlying cough: The most important consideration in the use of these drugs is discovering the cause of the underlying cough; prolonged use of the OTC preparations could result in the masking of important symptoms of a serious underlying disorder.  Respiratory: Rhinorrhea, bronchospasm.  Skin: Rash. ANTITUSSIVES Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology  ANTITUSSIVES Drugs Affecting the Respiratory System Cough is normally produced through the stimulation of sensory receptors of the glossopharyngeal and vagus nerves, innervating the mucous membranes of the lower pharynx, larynx, trachea, and smaller airways of the respiratory system. The receptors then transmit the signal to the cough center in the brain, which then triggers a reflex motor response that results in contraction of the muscles to close the glottis (vocal cords) and contraction of the muscles of expiration. The result is a sudden increase in intrathoracic pressure, followed by relaxation of the vocal cords, resulting in rapid expulsion of air. Instructor, Nursing Pharmacology ANTITUSSIVES Suppresses cough reflex  Acting on the cough center in the brain  Decreasing the sensitivity of cough receptors  Interrupting cough impulse transmission  Numbing the cough receptors in the respiratory passages and lungs ANTITUSSIVES Suppresses cough reflex Persistent coughing can be exhausting and can cause muscle strain and further irritation of the respiratory tract. Many disorders of the respiratory tract are accompanied by an uncomfortable, unproductive cough. Note: Coughing is a naturally protective way to clear the airway of secretions or any collected material, and antitussives prevent these actions. 3 TYPES OF ANTITUSSIVES CENTRALLY-ACTING Centrally acting agents work by inhibiting the cough center in the brain, elevating the threshold for coughing. Opiates such as codeine and hydrocodone also work through a central mechanism. PERIPHERAL-ACTING Peripheral-acting agents work either by anesthetizing the local nerve endings or acting. COMBINATION PREPARATION PROTOTYPE AND COMMON DRUGS CENTRALLY-ACTING  Prototype: dextromethorphan (Benylin, Robitussin)  Others: codeine, hydrocodone (Hycodon) PERIPHERAL-ACTING  Prototype: camphor and menthol  Others: benzonatate (Tessalon), levodropropizine COMBINATION PREPARATION INDICATION / CONTRAINDICATION INDICATION Cough CONTRAINDICATION None of major significance Notify physician if:  Patients who need to cough to maintain airways  Patients impaired by copious secretions, head injury  Pregnancy & lactation MECHANISM OF ACTION Antitussives act on the cough center in the brain and decrease the sensitivity of cough receptors. When the cough receptors in the respiratory passages and lungs are stimulated, they send signals to the cough center located in the brain. PHARMACOKINETICS  Dextromethorphan has an onset of action of 15 to 30 minutes and a duration of 3 to 6 hours.  Camphor and menthol are used topically or are inhaled through a vaporizer. When the medication is applied topically, the vapors are inhaled. CAUTION! Emphysema & asthma Addiction history Activities requiring mental alertness *Treatment of chronic cough must include investigations into the possible cause of the cough in addition to symptomatic treatment. SIDE EFFECTS Dextromethorphan  Drowsiness  Nausea  Dizziness Opiates Main side effects are sedation and constipation at the lower doses used to suppress cough. Several other side effects, many seen at higher doses or with chronic use. DRUG-DRUG INTERACTION + alcohol, narcotics, sedatives, hypnotics, barbiturates, & anti- depressants = CNS depression + sympathomimetics = toxicity + adrenolytics = decreased effect ANTITUSSIVES, EXPECTORANTS, MUCOLYTICS Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology ANTIHISTAMINES Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology  ANTIHISTAMINES Drugs Affecting the Respiratory System WHY ARE WE ALLERGIC? Instructor, Nursing Pharmacology ANTIHISTAMINES  It selectively block the effects of histamine at the histamine- 1 receptor sites, decreasing the allergic response. Antihistamines are used for the relief of symptoms associated with seasonal and perennial allergic rhinitis, allergic conjunctivitis, uncomplicated urticaria, and angioedema. ANTIHISTAMINES When choosing an antihistamine, the individual patient’s reaction to the drug is usually the governing factor. Because first-generation antihistamines have greater anticholinergic effects with resultant drowsiness, a person who needs to be alert should be given one of the second-generation, less sedating antihistamines. Because of their OTC availability, these drugs are often misused to treat colds and influenza. COMMON DRUGS First-generation anti-histamines Second-generation anti-histamines COMMON DRUGS First-generation anti-histamines  brompheniramine (Bidhist)  carbinoxamine (Histex, Palgic)  chlorpheniramine (Aller-Chlor)  clemastine (Tavist)  cyclizine (Marezine)  cyproheptadine  dexchlorpheniramine  dimenhydrinate (Dimetabs)  diphenhydramine (Benadryl)  hydroxyzine (Vistaril)  meclizine (Antivert)  promethazine (Phenergan)  triprolidine (Zymine) COMMON DRUGS Second-generation anti-histamines  azelastine (Asteline)  cetirizine (Zyrtect)  desloratadine (Clarinex)  fexofenadine (Allegra)  levocetirizine (Xyzal)  loratadine (Claritin) CONTRAINDICATION Pregnancy and lactation. Antihistamines are contraindicated during pregnancy and lactation unless the benefit to the mother clearly outweighs the potential risk to the fetus or baby. Renal or hepatic impairment. They should be used with caution in renal or hepatic impairment, which could alter the metabolism and excretion of the drug. Arrhythmias. Special care should be taken when these drugs are used by any patient with a history of arrhythmias or prolonged QT intervals because fatal cardiac arrhythmias have been associated with the use of certain antihistamines and drugs that increase QT intervals, including erythromycin. PHARMACOKINETICS CAUTION! Renal & hepatic impairment History of arrhythmia SIDE EFFECTS CNS Drowsiness and sedation. GI Drying of the GI mucous membranes, GI upset, nausea. GU Dysuria, urinary hesitancy. Skin Skin eruption and itching. DRUG-DRUG INTERACTION  Diphenhydramine + MAOI = prolonged anticholinergic effect  Diphenhydramine + alcohol, narcotics, hypnotics or barbiturates = CNS depression  Fexofenadine + Ketoconazole/ erythromycin = increase concentration of drug DECONGESTANTS Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology  DECONGESTANTS Constrict blood vessels by Drugs Affecting the Respiratory System stimulating alpha 1 adrenergic nerve receptors ↓ blood flow in edematous area, slow formation of mucus better drainage & relieves discomfort Instructor, Nursing Pharmacology DECONGESTANTS Decongestants are a type of medicine that can provide short-term relief for a blocked or stuffy nose (nasal congestion). They work by reducing the swelling of the blood vessels in your nose, which helps to open the airways. TYPES OF DECONGESTANTS Decongestants are available as: Nasal sprays Topical agents Drops Tablets or capsules Liquids or syrups Flavored powders to dissolve in water COMMON DRUGS: Topical Nasal Sympathomimetic imitate effects of sympathetic nervous system → vasoconstriction → ↓ edema & inflammation → opens nasal passages, promoting comfort & drainage of secretions. Examples: Oxymetazoline, and Xylometazoline COMMON DRUGS: Oral Constrict blood vessels by stimulating alpha adrenergic receptors. Example: Phenylpropanolamine, Phenylephrine COMMON DRUGS: Nasal Steroid Acts directly on effects of inflammation. For treatment of allergic/ seasonal rhinitis Examples: Nasacort, Flonase, and Rhinocort CONTRAINDICATION TOPICAL NASAL DECONGESTANT Lesion or erosion in the mucous membrane Glaucoma, hypertension, diabetes, thyroid disease, coronary disease, prostate problems ORAL DECONGESTANT Glaucoma, hypertension, diabetes, thyroid disease, coronary disease, prostate problems NASAL STEROID DECONGESTANT Acute infections Tuberculosis Glaucoma, hypertension, diabetes, thyroid disease, coronary disease, prostate problems PHARMACOKINETICS It varies depending on the route of administration  Glaucoma CAUTION! Poorly controlled HTN Notify the physician if the patient has the following medical condition: Heart conditions Thyroid problems Enlarged prostate Diabetes SIDE EFFECTS Decongestant medicines do not usually have side effects, and any side effects you may experience are usually mild. Possible side effects can include:  feeling sleepy (look for non-drowsy medicines)  irritation of the lining of your nose  headaches  feeling or being sick  a dry mouth  feeling restless or agitated  a rash These side effects should go away once you stop taking the medicine. More serious side effects can also happen, such as hallucinations and severe allergic reactions (anaphylaxis), but these are very rare. DRUG-DRUG INTERACTION Decongestants can increase or decrease the effect of some other medicines. For example, taking decongestants alongside some antidepressants can cause a dangerous rise in blood pressure. It's also important to be careful when taking other medicines if you're using an "all-in-1" decongestant remedy. "All-in-1" decongestants also contain painkillers or antihistamines, so it could be dangerous to take extra doses of these medicines at the same time. NOTE: Ask a pharmacist or GP before taking decongestants if you're taking other medicines. DRUG-DRUG INTERACTION + cyclopropane/halothane = cardiovascular effect + sympathomimetic = toxicity + adrenolytic = decreased effect + OTC drugs with pseudoephedrine = toxicity + MAOI = ↑ risk of hypertension & cardiac dysrhtyhmia + caffeine = restlessness & palpitations + Pseudoephedrine + beta blockers = ↓ effects of beta blockers  BRONCHODILATORS OR ANTIASTHMATICS Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology  BRONCHODILATORS OR ANTIASTHMATICS Drugs Affecting the Respiratory System  Asthma is characterized by reversible bronchospasm, inflammation, and hyperactive airways.  The hyperactivity is triggered by allergens or non-allergic inhaled irritants, or by factors such as exercise and emotions.  The trigger causes an immediate release of histamine, which results in bronchospasm in about 10 minutes.  The later response (3-5 hours) is cytokine-mediated inflammation, mucus production, and edema contributing to obstruction.  Appropriate treatment depends on understanding the early and late responses.  The extreme case of asthma is called status asthmaticus; this is life-threatening bronchospasm that does not respond to usual treatment and occludes airflow into the lungs. Instructor, Nursing Pharmacology BROCHDILATORS OR ANTIASTHMATICS  Medications used to facilitate respiration by dilating the airways. They are helpful in symptomatic relief or prevention of bronchial asthma and for bronchospasm associated with COPD. TYPES Xanthines Sympathomimetics Anticholinergics Xanthines  aminophylline (Truphylline)  caffeine  dyphylline (Dilor)  theophylline (Slo-Bid, Theo-Dur) Sympathomimetics  albuterol (Proventil)  arformoterol (Brovana)  ephedrine  epinephrine (Sus-Phrine)  formoterol (Foradil)  indacaterol (Arcapta)  isoetharine  isoproterenol (Isuprel)  levalbuterol (Xopenex)  metaproterenol (Alupent)  pirbuterol (Maxair)  salmeterol (Serevent)  terbutaline (Brethaire) Anticholinergics  ipratropium (Atrovent)  tiotropium (Sprival) XANTHINES XANTHINES A direct effect on the smooth muscles of the respiratory tract, both in the bronchi and in the blood vessels. A theory suggests that xanthines work by directly affecting the mobilization of calcium within the cell. They do this by stimulating two prostaglandins, resulting in smooth muscle relaxation, which increases the vital capacity that has been impaired by the bronchospasm or air trapping. Xanthines also inhibit the release of slow- reacting substance of anaphylaxis and histamine, decreasing the bronchial swelling and narrowing that occurs as a result of these two chemicals. Xanthines  aminophylline (Truphylline)  caffeine  dyphylline (Dilor)  theophylline (Slo-Bid, Theo-Dur) PHARMACOKINETICS OF XANTHINES CONTRAINDICATIONS OF XANTHINES  Co-morbidities. Caution should be taken with any patient with GI problems, coronary disease, respiratory dysfunction, renal or hepatic disease, alcoholism, or hyperthyroidism because these conditions can be exacerbated by the systemic effects of xanthines.  Long-term parenteral use. Xanthines are available for oral and parenteral use; the parenteral drug should be switched to oral form as soon as possible because the systemic effects of the oral form are less acute and more manageable.  Pregnancy. Although no studies are available of xanthine effects on human pregnancy, they have been associated with fetal abnormalities and breathing difficulties at birth in animal studies, so use should be limited to situations in which the benefit to the mother clearly outweighs the potential risk to the fetus.  Lactation. Because the xanthines enter breastmilk and could affect the baby, another method of feeding the baby should be selected if these drugs are needed during lactation. SIDE EFFECTS OF XANTHINES  CNS: Irritability, restlessness, dizziness.  Cardiovascular: Palpitations, life- threatening arrhythmias.  Others: Loss of appetite, fever, flushing.  GU: Proteinuria.  Respiratory: Respiratory arrest. DRUG-DRUG INTERACTIONS OF XANTHINES Because of the mechanism of xanthine metabolism in the liver, many drugs interact with xanthines. Nicotine. Nicotine increases the metabolism of xanthines in the liver; xanthine dose must be increased in patients who continue to smoke while using xanthines. SYMPATHOMIMETICS SYMPATOMIMETICS  Sympathomimetics are drugs that mimic the effects of the sympathetic nervous system.  One of the actions of the sympathetic nervous system is dilation of the bronchi with increased rate and depth of respiration.  This is the desired effect when selecting a sympathomimetic as a bronchodilator. Sympathomimetics  albuterol (Proventil)  arformoterol (Brovana)  ephedrine  epinephrine (Sus-Phrine)  formoterol (Foradil)  indacaterol (Arcapta)  isoetharine  isoproterenol (Isuprel)  levalbuterol (Xopenex)  metaproterenol (Alupent)  pirbuterol (Maxair)  salmeterol (Serevent)  terbutaline (Brethaire) THERAPEUTIC ACTIONS OF SYMPATHOMIMETICS  At therapeutic levels, the action of most sympathomimetics are specific to the beta-receptors found in the bronchi.  Other systemic effects include increased blood pressure, increased heart rate, vasoconstriction, and decreased renal and GI blood flow- all actions of the sympathetic nervous system.  Epinephrine, the prototype drug, is the drug of choice for adults and children for the treatment of acute bronchospasm, including that caused by anaphylaxis; it is also available for inhalation. INDICATIONS OF SYMPATHOMIMETICS  Long-acting treatment and prophylaxis of bronchospasm and prevention of exercise- induced bronchospasm in patients 2 years and older.  Long-term maintenance treatment of bronchoconstriction in COPD.  Treatment of acute bronchospasm in adults and children, although epinephrine is the drug of choice.  Treatment and prophylaxis of acute asthma attacks in children more than 6 years old. PHARMACOKINETICS OF SYMPATHOMIMETICS CONTRAINDICATIONS OF SYMPATHOMIMETICS  Underlying conditions. These drugs are contraindicated or should be used with caution, depending on the severity of the underlying condition, in conditions that would be aggravated by the sympathetic stimulation, including cardiac disease, vascular disease, arrhythmias, diabetes, and hyperthyroidism.  Pregnancy and lactation. These drugs should be used during pregnancy and lactation only if the benefits to the mother clearly outweigh potential risks to the fetus or neonate. SIDE EFFECTS OF SYMPATHOMIMETICS  CNS: Headache, restlessness.  Cardiovascular: Palpitation, tachycardia.  Skin: Pallor, local burning and stinging.  GU: Decreased renal formation.  Respiratory: Rebound congestion with nasal inhalation.  Misc: Fear, anxiety. DRUG-DRUG INTERACTIONS OF SYMPATHOMIMETICS  Special precautions should be taken to avoid the combination of sympathomimetic bronchodilators with the general anesthetics.  Cyclopropane and halogenated hydrocarbons. Because these drugs sensitize the myocardium to catecholamines, serious cardiac complications could occur. ANTICHOLINERGICS ANTICHOLINERGICS  Patients who cannot tolerate the sympathetic effects of sympathomimetics might respond to the anticholinergic drugs ipratropium (Atrovent) and tiotropium (Spiriva).  These drugs are not as effective as the sympathomimetics but can provide some relief to those patients who cannot tolerate the other drugs. Anticholinergics  ipratropium (Atrovent)  tiotropium (Sprival) THERAPEUTIC ACTIONS OF ANTICHOLINERGICS  Anticholinergics are used as bronchodilators because of their effect on the vagus nerve, which sis to block or antagonize the action of the neurotransmitter acetylcholine at vagal- mediated receptor sites.  By blocking the vagal effect, relaxation of smooth muscle in the bronchi occurs, leading to bronchodilation. INDICATIONS OF ANTICHOLINERGICS  Maintenance and treatment of bronchospasm for adults with COPD.  Long-term, once-daily maintenance and treatment of bronchospasm associated with COPD in adults. PHARMACOKINETICS OF ANTICHOLINERGICS CONTRAINDICATIONS OF ANTICHOLINERGICS  Co-morbidities. Caution should be used in any condition that would be aggravated by the anticholinergic or atropine-like effects of the drug, such as narrow-angle glaucoma, bladder neck obstruction or prostatic hypertrophy, and conditions aggravated by dry mouth and throat.  Allergy. The use of ipratropium or tiotropium is contraindicated in the presence of known allergy to the drug or to soy products or peanuts to prevent hypersensitivity reactions.  Pregnancy and lactation. These drugs are not usually absorbed systematically, but as with all the drugs, caution should be used in pregnancy and lactation because of the potential for adverse effects on the fetus or nursing baby. SIDE EFFECTS OF ANTICHOLINERGICS  CNS: Dizziness, headache.  GI: Nausea, gastrointestinal distress.  Cardiovascular: Palpitations.  Respiratory: Cough.  Misc: Nervousness. NURSING RESPONSIBILITIES  Relieve GI upset. Administer oral drug with food or milk to relieve GI irritation if GI upset is a problem.  Monitor drug response. Monitor patient response to the drug (e.g., relief of respiratory difficulty, improved airflow) to determine the effectiveness of the drug dose and to adjust dose as needed.  Provide comfort. Provide comfort measures including rest periods, quiet environment, dietary control of caffeine, and headache therapy as needed, to help the patient cope with the effects of drug terapy. NURSING RESPONSIBILITIES  Provide follow-ups. Provide periodic follow-up, including blood tests, to monitor serum theophylline levels.  Individual drug response. Reassure patient that the drug of choice will vary with each individual; these sympathomimetics are slightly different chemicals and are prepared in a variety of delivery systems; a patient may have to try several different sympathomimetics before the most effective one is found.  Proper administration and dosage. Advise the patient to use the minimal amount needed for the shortest period necessary to prevent adverse effects and accumulation of drug levels. NURSING RESPONSIBILITIES  Proper use of sympathomimetics. Teach the patients who use one of these drugs for exercise-induced asthma to use it 30 to 60 minutes before exercising to ensure peak therapeutic effects when they are needed.  Use of adrenergic blockers. Alert the patient that long-acting adrenergic blockers are not for use during acute attacks because they are slower acting and will not provide the necessary rescue in a state of acute bronchospasm.  Increase oral fluid intake. Ensure adequate hydration and provide environmental controls such as the use of a humidifier, to make the patient more comfortable.  Encourage voiding. Encourage the patient to void before each dose of medication to avoid urinary retention related to drug effects. NURSING RESPONSIBILITIES  Small, frequent meals. Provide small, frequent meals and sugarless lozenges to relieve dry mouth and GI upset.  Use of inhalator. Review the use of inhalator with the patient; caution the patient not to exceed 12 inhalations in 24 hours to prevent serious adverse effects.  Educate the patient. Provide thorough patient teaching, including the drug name and prescribed dosage measures to help avoid adverse effects, warning signs that may indicate problems, and the need for periodic monitoring and evaluation, to enhance patient knowledge about drug therapy and to promote compliance.  Provide patient support. Offer support and encouragement to help the patient cope with the disease and the drug regimen. Drugs Affecting the Respiratory System Instructor, Nursing Pharmacology