Antihistamines: A Detailed Overview PDF

CHAPTER 36 ANTIHISTAMINES, DECONGESTANTS, ANTITUSSIVES, AND EXPECTORANTS UNDERSTANDING THE COMMON COLD Most caused by viral infection (rhinovirus or influenza virus) Virus invades tissues (mucosa) of upper respiratory tract, causing upper respiratory infection (URI) Excessive mucus production result...

CHAPTER 36 ANTIHISTAMINES, DECONGESTANTS, ANTITUSSIVES, AND EXPECTORANTS UNDERSTANDING THE COMMON COLD Most caused by viral infection (rhinovirus or influenza virus) Virus invades tissues (mucosa) of upper respiratory tract, causing upper respiratory infection (URI) Excessive mucus production results from the inflammatory response to this invasion. Fluid drips down the pharynx into the esophagus and lower respiratory tract, causing cold symptoms: sore throat, coughing, upset stomach. Irritation of nasal mucosa often triggers the sneeze reflex. Mucosal irritation also causes release of several inflammatory and vasoactive substances, dilating small blood vessels in the nasal sinuses and causing nasal congestion. 2 Involves combined use of antihistamines, nasal decongestants, antitussives, and expectorants Treatment is symptomatic only, not curative. TREATMENT OF THE COMMON COLD Symptomatic treatment does not eliminate the causative pathogen. Difficult to identify whether cause is viral or bacterial Treatment is “empiric therapy,” treating the most likely cause Antivirals and antibiotics may be used, but a definite viral or bacterial cause may not3 be easily identified. PEDIATRIC CONCERNS IN 2008 THE FDA ISSUED RECOMMENDATIONS THAT OTC COUGH AND COLD PRODUCTS NOT BE GIVEN TO CHILDREN YOUNGER THAN 2 YEARS OF AGE. OVERSEDATION, SEIZURES, TACHYCARDIA, AND EVEN DEATH IN TODDLERS EVIDENCE: NOT EFFECTIVE IN SMALL CHILDREN PARENTS ARE ADVISED TO CONSULT THEIR CHILDREN’S PEDIATRICIANS A 2010 STUDY A DRAMATIC DECREASE IN YOUNG CHILDREN’S EMERGENCY DEPARTMENT VISITS SINCE THE 2008 FDA RECOMMENDATION. 4 Drugs that directly compete with histamine for specific receptor sites ANTIHISTAMINES Two histamine receptors H1 (histamine 1) H2 (histamine 2) 5 ANAPHYLAXIS SEVERE ALLERGIC REACTIONS RELEASE OF EXCESSIVE AMOUNTS OF HISTAMINE CAN LEAD TO: CONSTRICTION OF SMOOTH MUSCLE, ESPECIALLY IN THE STOMACH AND LUNGS INCREASE IN BODY SECRETIONS VASODILATATION AND INCREASED CAPILLARY PERMEABILITY, MOVEMENT OF FLUID OUT OF THE BLOOD VESSELS AND INTO THE TISSUES, AND DROP IN BLOOD PRESSURE AND EDEMA 6 HISTAMINE MAJOR INFLAMMATORY MEDIATOR IN MANY ALLERGIC DISORDERS ALLERGIC RHINITIS (E.G., HAY FEVER AND MOLD, DUST ALLERGIES) ANAPHYLAXIS ANGIOEDEMA DRUG FEVERS INSECT BITE REACTIONS URTICARIA (ITCHING) 7 H1 antagonists (also called H1 blockers) ANTIHISTAMINES AND HISTAMINE ANTAGONISTS Examples: chlorpheniramine, fexofenadine (Allegra), loratadine (Claritin), cetirizine (Zyrtec), diphenhydramine (Benadryl) Antihistamines have several properties Antihistaminic Anticholinergic Sedative 8 ANTIHISTAMINES H2 BLOCKERS OR H2 ANTAGONISTS USED TO REDUCE GASTRIC ACID IN PEPTIC ULCER DISEASE EXAMPLES: CIMETIDINE (TAGAMET), FAMOTIDINE (PEPCID), NIZATIDINE (AXID) 9 BLOCK ACTION OF HISTAMINE AT H1 RECEPTOR SITES ANTIHISTAMINE MECHANISM OF ACTION COMPETE WITH HISTAMINE FOR BINDING AT UNOCCUPIED RECEPTORS CANNOT PUSH HISTAMINE OFF THE RECEPTOR IF ALREADY BOUND THE BINDING OF H1 BLOCKERS TO THE HISTAMINE RECEPTORS PREVENTS THE ADVERSE CONSEQUENCES OF HISTAMINE STIMULATION. MORE EFFECTIVE IN PREVENTING, THAN REVERSING THEM-GIVE EARLY 10 HISTAMINE VERSUS ANTIHISTAMINE EFFECTS HISTAMINE EFFECTS DILATION AND INCREASED PERMEABILITY (ALLOWING SUBSTANCES TO LEAK INTO TISSUES) STIMULATE SALIVARY, GASTRIC, LACRIMAL, AND BRONCHIAL SECRETIONS MAST CELLS RELEASE HISTAMINE AND OTHER SUBSTANCES, RESULTING IN ALLERGIC REACTIONS ANTIHISTAMINE EFFECTS REDUCE DILATION OF BLOOD VESSELS REDUCE PERMEABILITY OF BLOOD VESSELS ANTICHOLINERGIC: DRYING EFFECT THAT REDUCES NASAL, SALIVARY, AND LACRIMAL GLAND SECRETIONS (RUNNY NOSE, TEARING, AND ITCHING EYES) REDUCE GASTRIC AND BRONCHIAL 11 SECRETIONS SEDATIVE ANTIHISTAMINES: INDICATIONS Management of: Nasal allergies Seasonal or perennial allergic rhinitis (hay fever) Allergic reactions Motion sickness Parkinson’s disease Sleep disorders Also used to relieve symptoms associated with the common cold Sneezing, runny nose Palliative treatment; not curative 12 Known drug allergy Narrow-angle glaucoma Cardiac disease, hypertension Kidney disease ANTIHISTAMINES CONTRAINDICATIONS Bronchial asthma, chronic obstructive pulmonary disease (COPD) Sole drug therapy during acute asthmatic attacks Albuterol or epinephrine indicated for acute asthma attacks Peptic ulcer disease Seizure disorders Benign prostatic hyperplasia (BPH) Pregnancy 13 ANTIHISTAMINES: ADVERSE EFFECTS Anticholinergic (drying) effects: most common Dry mouth Difficulty urinating Constipation Changes in vision Drowsiness Mild drowsiness to deep sleep 14 ANTIHISTAMINES: TWO TYPES Traditional: brompheniramine, chlorpheniramine, dimenhydrinate, diphenhydramine, meclizine, and promethazine Nonsedating: loratadine, cetirizine, and fexofenadine 15 NONSEDATING/PERIPHERALLY ACTING ANTIHISTAMINES Developed to eliminate unwanted adverse effects, mainly sedation Work peripherally to block the actions of histamine; thus, fewer central nervous system (CNS) adverse effects Longer duration of action (increases compliance) Examples: fexofenadine (Allegra), loratadine (Claritin), cetirizine (Zyrtec) 16 TRADITIONAL ANTIHISTAMINES Older Work both peripherally and centrally Have anticholinergic effects, making them more effective than nonsedating drugs in some cases Examples: diphenhydramine, brompheniramine, chlorpheniramine, dimenhydrinate, meclizine, 17 promethazine ANTIHISTAMINES: NURSING IMPLICATIONS Gather data about the condition or allergic reaction that required treatment; also assess for drug allergies. Contraindicated in the presence of acute asthma attacks and lower respiratory diseases, such as pneumonia Use with caution in patients with increased intraocular pressure, cardiac or renal disease, hypertension, asthma, COPD, peptic ulcer disease, BPH, or pregnancy. 18 ANTIHISTAMINES: NURSING IMPLICATIONS (CONT.) INSTRUCT PATIENTS TO REPORT EXCESSIVE SEDATION, CONFUSION, OR HYPOTENSION. INSTRUCT PATIENTS TO AVOID DRIVING OR OPERATING HEAVY MACHINERY; ADVISE AGAINST CONSUMING ALCOHOL OR OTHER CNS DEPRESSANTS. INSTRUCT PATIENTS NOT TO TAKE THESE MEDICATIONS WITH OTHER PRESCRIBED OR OTC MEDICATIONS WITHOUT CHECKING WITH THEIR PRESCRIBERS. 19 ANTIHISTAMINES: NURSING IMPLICATIONS (CONT.) Best tolerated when taken with meals; reduces GI upset If dry mouth occurs, teach patients to perform frequent mouth care, chew gum, or suck on hard candy (preferably sugarless) to ease discomfort. Monitor for intended therapeutic effects. 20 NASAL CONGESTION Excessive nasal secretions Inflamed and swollen nasal mucosa Primary causes Allergies URIs (common cold) 21 DECONGESTANTS: TYPES THREE MAIN TYPES ARE USED: ADRENERGICS LARGEST GROUP SYMPATHOMIMETICS ANTICHOLINERGICS LESS COMMONLY USED PARASYMPATHOLYTICS CORTICOSTEROIDS TOPICAL, INTRANASAL STEROIDS TWO DOSAGE FORMS ORAL INHALED OR TOPICALLY APPLIED TO THE NASAL MEMBRANES 22 ORAL DECONGESTANTS Prolonged decongestant effects but delayed onset Effect less potent than topical No rebound congestion Exclusively Adrenergics: constricting the small arterioles; When these blood vessels are stimulated by alpha-adrenergic drugs, they constrict. Example: pseudoephedrine (Sudafed) 23 TOPICAL NASAL DECONGESTANTS TOPICAL ADRENERGICS PROMPT ONSET POTENT SUSTAINED USE OVER SEVERAL DAYS CAUSES REBOUND CONGESTION, MAKING THE CONDITION WORSE. EPHEDRINE, OXYMETAZOLINE, PHENYLEPHRINE, AND TETRAHYDROZOLINE 24 INHALED INTRANASAL STEROIDS AND ANTICHOLINERGIC DRUGS INTRANASAL STEROIDS NOT ASSOCIATED WITH REBOUND CONGESTION OFTEN USED PROPHYLACTICALLY TO PREVENT NASAL CONGESTION IN PATIENTS WITH CHRONIC UPPER RESPIRATORY TRACT SYMPTOMS BUDESONIDE (RHINOCORT), FLUTICASONE (FLONASE), TRIAMCINOLONE (NASACORT INTRANASAL ANTICHOLINERGIC IPRATROPIUM (ATROVENT) 25 NASAL DECONGESTANTS: MECHANISM OF ACTION Site of action: blood vessels surrounding nasal sinuses Adrenergics Constrict small blood vessels that supply upper respiratory tract structures As a result, these tissues shrink, and nasal secretions in the swollen mucous membranes are better able to drain. Nasal steroids Antiinflammatory effect Work to turn off the immune system cells involved in the inflammatory response Decreased inflammation results in decreased congestion. 26 NASAL DECONGESTANTS DRUG EFFECTS SHRINK ENGORGED NASAL MUCOUS MEMBRANES RELIEVE NASAL STUFFINESS INDICATIONS RELIEF OF NASAL CONGESTION ASSOCIATED WITH: ACUTE OR CHRONIC RHINITIS COMMON COLD SINUSITIS HAY FEVER OTHER ALLERGIES MAY ALSO BE USED TO REDUCE SWELLING OF THE NASAL PASSAGE AND FACILITATE VISUALIZATION OF THE NASAL OR PHARYNGEAL MEMBRANES BEFORE SURGERY OR DIAGNOSTIC PROCEDURES 27 NASAL DECONGESTANTS: CONTRAINDICATIONS DRUG ALLERGY NARROW-ANGLE GLAUCOMA UNCONTROLLED CARDIOVASCULAR DISEASE, HYPERTENSION DIABETES AND HYPERTHYROIDISM HISTORY OF CEREBROVASCULAR ACCIDENT OR TRANSIENT ISCHEMIC ATTACKS LONG-STANDING ASTHMA BPH DIABETES 28 Adrenergics Steroids Palpitations Nervousness Local mucosal dryness Insomnia and irritation Tremors (Excessive doses may result in systemic effects caused by adrenergic stimulation of the heart, blood vessels, and CNS) NASAL DECONGESTANTS: ADVERSE EFFECTS 29 NASAL DECONGESTANTS: INTERACTIONS SYSTEMIC SYMPATHOMIMETIC DRUGS AND SYMPATHOMIMETIC NASAL DECONGESTANTS ARE LIKELY TO CAUSE DRUG TOXICITY WHEN GIVEN TOGETHER. MONOAMINE OXIDASE INHIBITORS AND SYMPATHOMIMETIC NASAL DECONGESTANTS RAISE BLOOD PRESSURE. 30 NASAL DECONGESTANTS: NURSING IMPLICATIONS PATIENTS SHOULD AVOID CAFFEINE AND CAFFEINECONTAINING PRODUCTS. PATIENTS SHOULD REPORT A FEVER, COUGH, OR OTHER SYMPTOMS LASTING LONGER THAN 1 WEEK. MONITOR FOR INTENDED THERAPEUTIC EFFECTS. 31 COUGH PHYSIOLOGY RESPIRATORY SECRETIONS AND FOREIGN OBJECTS ARE NATURALLY REMOVED BY THE COUGH REFLEX. INDUCES COUGHING AND EXPECTORATION INITIATED BY IRRITATION OF SENSORY RECEPTORS IN THE RESPIRATORY TRACT 32 TWO BASIC TYPES OF COUGH PRODUCTIVE COUGH CONGESTED; REMOVES EXCESSIVE SECRETIONS NONPRODUCTIVE COUGH DRY COUGH MOST OF THE TIME, COUGHING IS BENEFICIAL. REMOVES EXCESSIVE SECRETIONS REMOVES POTENTIALLY HARMFUL FOREIGN SUBSTANCES IN SOME SITUATIONS, COUGHING CAN BE HARMFUL, SUCH AS AFTER HERNIA REPAIR SURGERY. 33 ANTITUSSIVES DRUGS USED TO STOP OR REDUCE COUGHING OPIOID AND NONOPIOID USED ONLY FOR NONPRODUCTIVE COUGHS! MAY BE USED IN CASES WHEN COUGHING IS HARMFUL 34 ANTITUSSIVES: MECHANISM OF ACTION OPIOIDS SUPPRESS THE COUGH REFLEX BY DIRECT ACTION ON THE COUGH CENTER IN THE MEDULLA ANALGESIA, DRYING EFFECT ON THE MUCOSA OF THE RESPIRATORY TRACT, INCREASED VISCOSITY OF RESPIRATORY SECRETIONS, REDUCTION OF RUNNY NOSE AND POSTNASAL DRIP EXAMPLES CODEINE HYDROCODONE 35 ANTITUSSIVES: MECHANISM OF ACTION (CONT.) NONOPIOIDS DEXTROMETHORPHAN: WORKS IN THE SAME WAY NO ANALGESIC PROPERTIES NO CNS DEPRESSION BENZONATATE SUPPRESS THE COUGH REFLEX BY NUMBING THE STRETCH RECEPTORS IN THE RESPIRATORY TRACT AND PREVENT REFLEX STIMULATION OF THE MEDULLARY COUGH CENTER 36 ANTITUSSIVES INDICATIONS USED TO STOP THE COUGH REFLEX WHEN THE COUGH IS NONPRODUCTIVE OR HARMFUL 37 ANTITUSSIVES: CONTRAINDICATIONS Drug allergy Opioid dependency Respiratory depression 38 ANTITUSSIVES: ADVERSE EFFECTS Benzonatate Dizziness, headache, sedation, nausea, and others Dextromethorphan Dizziness, drowsiness, nausea Opioids Sedation, nausea, vomiting, lightheadedness, constipation 39 Perform respiratory and cough assessment and assess for allergies. ANTITUSSIVES NURSING IMPLICATIONS Instruct patients to avoid driving or operating heavy equipment because of possible sedation, drowsiness, or dizziness. Report any of the following symptoms to the caregiver: Cough that lasts more than 1 week Persistent headache Fever Rash Antitussive drugs are for nonproductive coughs. Monitor for intended therapeutic effects. 40 EXPECTORANTS Drugs that aid in the expectoration (removal) of mucus Reduce the viscosity of secretions Disintegrate and thin secretions Example: guaifenesin 41 EXPECTORANTS MECHANISMS OF ACTION Reflex stimulation Drug causes irritation of the GI tract. Loosening and thinning of respiratory tract secretions occur in response to this irritation. Direct stimulation The secretory glands are stimulated directly to increase their production of respiratory tract fluids. Final result: thinner mucus that is easier to remove 42 EXPECTORANTS DRUG EFFECTS BY LOOSENING AND THINNING SPUTUM AND BRONCHIAL SECRETIONS, THE TENDENCY TO COUGH IS INDIRECTLY DIMINISHED. 43 EXPECTORANTS INDICATIONS USED FOR THE RELIEF OF PRODUCTIVE COUGHS ASSOCIATED WITH: COMMON COLD BRONCHITIS LARYNGITIS PHARYNGITIS COUGHS CAUSED BY CHRONIC PARANASAL SINUSITIS PERTUSSIS INFLUENZA MEASLES 44 used with caution in older adults and patients with asthma or respiratory insufficiency. EXPECTORANTS: NURSING IMPLICATIONS Increase fluids, if permitted, to help loosen and liquefy secretions. Report a fever, cough, or other symptoms lasting longer than 1 week. Monitor for intended therapeutic effects. 45