Chapter 36: Antihistamines, Decongestants, Antitussives and Expectorants Flashcards
Antihistamines, Decongestants, Antitussives and Expectorants treat
Upper respiratory tract infections
Cold is most often caused by
Virus, and also by bacteria
Typical S&S of a Cold
Sore throat, coughing and upset stomach
Excessive mucus =
Inflammatory response
Irritation of nasal mucosa triggers
Sneeze reflex
Nasal congestion
Dilation of small blood vessel in nasal sinuses from mucosal irritation
Treatments for Colds
Empiric Therapy (Is symptomatic, not curative) Herbals: echinacea and goldenseal
The highest priority for pt education of OTC meds
Do NOT use in children < 2 years unless prescribed
Empiric Therapy
Treating based on S&S rather than actual cause of disease
Antihistamines are responsible for
blocking histamine a in inflammatory response in mast cells.
Antihistamines
Directly compete w/ histamine for specific receptor sites
Antihistamines include
Chlorpheniramine fexofenadine loratadine cetirizine diphenhydramine
Histamine1 Receptors
Mediates smooth muscle contraction and dilation of capillaries.
Increases histamine
Increased histamine =
Anaphylaxis
Functions of Histamine1
- Nerve impulse transmission in CNS
- Dilate capillaries and contract smooth muscle
- Stimulation of gastric secretions and increased HR
Histamine1 agonists (aka Antihistamines) are more effective in
Preventing actions rather than reversing them, therefore give earlier in traeatment
Indications for Histamine1 Agonists
Management of nasal allergies, seasonal/perennial allergic rhinitis, and allergic reactions.
Relieves common cold: sneezing, runny nose, cough.
Also useful for vertigo, motion sickness, insomnia, and Parkinson’s disease.
Mechanism of Action: Histamine1 Agonists
- Released from mast cells, basophils, other cells in response to antigens.
- Block histamine receptors on basophils/mast cells.
- Prevent release/actions of histamine.
Antihistamines: MOA on Cardiovascular System
reduces dilation of the blood vessels
reduces increased permeability of the blood vessels
Antihistamines: MOA on Immune System
prevent release of histamine, binds to histamine receptors and prevents actions.
Antihistamines: MOA on Smooth Muscle
reduces salivary, gastric, lacrimal, bronchial sections
Antihistamines: MOA on the Skin
reduces capillary permeability, wheal flare formation, and itching
Antihistamines: Anticholinergic MOA
drying effect reducing nasal, salivary and lacrimal secretions (runny nose)
Contraindications of Histamine1 Agonists
- Presence of acute asthma attack and lower respiratory diseases (pneumonia)
- Caution in increased intraocular pressure, cardiac/renal disease, HTN, asthma, COPD, peptic ulcer disease, BPH, pregnancy
Adverse Effects of Histamine1 Agonists
CC- drowsiness
Anticholinergic (drying) effects most common (Dry mouth, difficulty urinating, constipation, changes in vision)
Nonsedating antihistamines include
Fexodenadine
Loratadine
Cetirizine
Nonsedating Antihistamines
Eliminates adverse effects mainly sedation
Work peripherally to block actions of histamine
Longer duration of action
Traditional Antihistamines include
Diphenhydramine
Chlorpheniramine
Dimenhydrinate
Meclizine
Traditional Antihistamines
Peripherally and centrally acting
Anticholinergic effects, makes more effective than nonsedating in some cases.
Antihistamine interactions
Cough syrup mixed with antihistamines can decrease CNS effects.
Nursing Implications: Antihistamines
- Gather data of condition/allergic reaction; assess for drug allergies
- Report excessive sedation, confusion, hypotension.
Antihistamines should be taken when in regards to meals?
Best taken with meals - Reduces GI upset
The nurse should advise the patient who is taking antihistamines to avoid what when taking this medication?
Avoid driving/ operating; Avoid consuming alcohol or CNS depressants
Antihistamines can cause dry mouth, therefore the nurse should have
Put perform frequent mouth care, chew gum, or suck on a hard, sugarless candy
You should discontinue antihistamine medications at least
4 days prior to allergy testing
Indications for Decongestants
Used to relieve nasal congestion r/t acute/chronic rhinitis, common cold, sinusitis, hay fever and other allergies
Used for ability to shrink engorged nasal mucous membranes
Decongestants
Decrease swelling of nasal passage and facilitate visualization of nasal/pharyngeal membranes before surgery/diagnostic procedures
Types of Decongesants
Oral Decongestants
Topical Adrenergics
Intranasal Steroids
Intranasal Anticholinergic
Rhinitis medicamentosa
Rebound congestion if nasal sprays are overused
Humidifier
Used to prevent nose bleeds from drying effect of nasal spray
Oral Decongestants include
Pseudoephedrine
Oral Decongestants
Prolonged effects, delayed onset
Less potent than topical
No rebound congestion
Exclusively adrenergic
Adrenergic
Sympathomimetic
Anticholinergic
Parasympathetic
Topical Adrenergics include
Phenylephrine
Topical Adrenergics
Prompt onset
Potent
Can cause rebound congestion
Intranasal Steroids include
beclomethasone dipropionate budesonide flunisolide fluticasone triamcinolone ciclesonide
Intranasal Anticholinergic
Ipratropium
Mechanism of Action: Adrenergic Decongestants
Constrict small blood vessels that supply UR tract structures
Tissues shrink, nasal secretions are better able to drain
Mechanism of Action: Nasal Steroids (Decongestant)
Anti-inflammatory effect
Turns off immune system cells involved in inflammatory response
Decreases inflammation = decreased congestion
Site of Action for Decongestants
Blood vessels surrounding nasal sinuses
Contraindications for Adrenergic Decongestants
- Narrow-angled glaucoma, uncontrolled CVD, HTN, diabetes, hyperthyroidism, prostatitis, atrial fibrillation
- Unable to close eyes.
- History of CVA, cerebral arteriosclerosis, long-standing asthma, BPH
Adverse Effects of Adrenergic Decongestants
Nervousness
Insomnia
Palpitations
Tremor
Adverse Effects of Intranasal Steroids (Decongestant)
Localized, mucosal dryness and irritation
Excessive dosages of decongestants can cause
Systemic effects of cardiovascular: HTN, palpitations
CNS effects: headache, nervousness and dizziness.
Nursing Implications for Decongestants
Avoid caffeine or caffeine-containing products
Report fever, cough, other symptoms lasting longer than a week
Indications for Antitussives
Nonproductive or harmful cough
Antitussives
Opioid vs nonopioid
Opioids include
Codeine and hydrocodone
Nonopioids include
Dextromethorphan, benzonatate levorphanol
Mechanism of Action: Opioids
Suppress cough reflex by direct action on cough center in medulla
Mechanism of Action: Nonopioids
Suppress cough reflex by numbing stretch receptors in respiratory tract and preventing the cough reflux from being stimulated
Contraindications of Antitussives
Opioid caution in elderly patient and alcohol use
Adverse Effects of Antitussives
Effect CNS
Adverse Effects of Nonopioids (Antitussives)
Benzonatate: Dizziness, headache, sedation, nausea, nasal congestion
Dextromethorphan: Sedation, nausea, drowsiness and dizziness
Adverse Effects of Opioids (Antitussives)
Sedation
N/V
Lightheadedness
Constipation
Nursing Implications for Antitussives
Perform respiratory and cough assessment
Avoid driving or operating heavy machinery
Report cough lasting more than a week, persistent headache, fever, rash.
Expectorant
Aid in expectoration (removal of mucus)
Decreases viscosity of secretions
Disintegrate and thin secretions
Expectorants include
Guaifensein
Mechanism of Action: Expectorant
Reflex Stimulation
Direct Stimulation
Loosening and thinning sputum and bronchial secretions -> tendency to cough is indirectly diminished.
Reflex Stimulation
Drug causes irritation of GI tract, loosening and thinning of respiratory tract secretions in response to this irritation
Direct Stimulation
Secretory glands are stimulated directly to increase their production of repository tract fluids
Indications for Expectorants
Relief of productive cough r/t common cold, bronchitis, laryngitis, pharyngitis, pertussis, influenza and measles
Nursing Implications for Expectorants
Used cautiously in elderly and those with asthma and respiratory insufficiency
Receive more fluids to help loosen and liquefy secretions.
Report fever, cough, other symptoms lasting longer than a week
Antihistamines have several properties
antihistaminic
anticholinergic
sedative
Histamine effects on the heart
dilation and increased permeability (allowing substances to leak into tissues)
Histamine effects on the immune system
mast cells release histamine and other substances, resulting in allergic reactions
Histamine effects on the smooth muscle
stimulates salivary, gastric, lacrimal and bronchial secretions
