chapter 37 antihistamines, decongestants, antitussives and expectorants - week 4 Flashcards
understanding common cold
- Most are caused by viral infection (rhinovirus or influenza virus).
- Virus invades tissues (mucosa) of upper respiratory tract, causing upper respiratory infection.
- 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 the release of several inflammatory and vasoactive substances, dilating small blood vessels in the nasal sinuses and causing nasal congestion.
treatment of common cold
- Involves combined use of antihistamines, nasal decongestants, antitussives, and expectorants
- Treatment is symptomatic only, not curative.
- Symptomatic treatment does not eliminate the causative pathogen.
- Difficult to identify whether cause is viral or bacterial
- Treatment is “empirical therapy,” treating the most likely cause
- Antivirals and antibiotics may be used, but a definite viral or bacterial cause may not be easily identified.
pediatric concerns with the common cold treatments
In 2009, Health Canada issued recommendations that over-the-counter (OTC) cough and cold products not be given to children younger than 6 years of age.
Not effective in small children, and parents are advised to consult their pediatrician on the best ways to manage these illnesses.
antihistamines
Drugs that directly compete with histamine for specific receptor sites
Histamine antagonists
H1-antagonists (or H1-blockers)
H2-antagonists (or H2 -blockers)
anaphylaxis
Release of excessive amounts of histamine can leading 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
histamine
Major inflammatory mediator in many allergic disorders
* Allergic rhinitis (e.g., hay fever and mould and dust allergies)
* Anaphylaxis
* Angioedema
* Drug fevers
* Insect bite reactions
* Urticaria (pale red, raised, itchy bumps)
h1- antagonists examples and properties
chlorpheniramine, fexofenadine (Allegra®), loratadine (Claritin®), cetirizine (Reactine®), desloratadine (Aerius®), diphenhydramine (Benadryl®)
- Antihistaminic
- Anticholinergic
- Sedative
h2 blockers or h2 antagonists
Used to reduce gastric acid in peptic ulcer disease
Examples: cimetidine, ranitidine (Zantac®), famotidine (Pepcid AC®), nizatidine (Axid®)
antihistamines mechanism of action
- Block action of histamine at H1-receptor sites
- 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.
* Vasodilation
* Increased gastrointestinal, respiratory, salivary, and lacrimal secretions
* Increased capillary permeability with resulting edema - More effective in preventing the actions of histamine than in reversing them
- Should be given early in treatment before all the histamine binds to the receptors
Histamine Versus Antihistamine Effects (cardiovasular)
Cardiovascular (small blood vessels)
Histamine effects:
dilation and increased permeability
(allowing substances to leak into tissues)
Antihistamine effects
dilates blood vessels
increases blood vessels permeability
Histamine Versus Antihistamine Effects (smooth muscles)
Smooth muscle (on exocrine glands)
Histamine effects: stimulation of salivary, gastric, lacrimal, and bronchial secretions
Antihistamine effects: reduction of salivary, gastric, lacrimal, and bronchial secretions
Histamine Versus Antihistamine Effects (immune sysem)
Immune system (release of substances commonly associated with allergic reactions)
Histamine effects: mast cells release histamine and other substances, resulting in allergic reactions
Antihistamine effects: bind to histamine receptors, thus preventing histamine from causing a response
anit histamines indications
Management of:
Nasal allergies
Seasonal or perennial allergic rhinitis (hay fever)
Allergic reactions
Motion sickness
Parkinson’s disease
Vertigo
Sleep disorders
Also used to relieve symptoms associated with the common cold
Sneezing, runny nose
Does not cure common cold
anithistamines contraindications
- Known drug allergy
- Acute-angle glaucoma
- Cardiac disease, hypertension
- Kidney disease
- Bronchial asthma, chronic obstructive pulmonary disease (COPD)
- Not to be used as sole drug therapy during acute asthmatic attacks
- salbutamol or epinephrine
- Peptic ulcer disease
- Seizure disorders
- Benign prostatic hyperplasia
- Pregnancy
antihistamine pediatric considerations
Fexofenadine hydrochloride is not recommended for children under 6 years of age or for those with kidney impairment.
Desloratadine is not recommended for children.
Loratadine is not recommended for children younger than 2 years of age.
antihistamines adverse effects
- Anticholinergic (drying) effects: most common
- Dry mouth
- Difficulty urinating
- Constipation
- Changes in vision
- Cardiovascular, central nervous system, gastrointestinal, and other effects
- Drowsiness
- Mild drowsiness to deep sleep
two types of anti histamines
Traditional: brompheniramine, chlorpheniramine, dimenhydrinate, diphenhydramine, and promethazine
Nonsedating: loratadine, cetirizine, and fexofenadine
nonsedating antihistamines
- Developed to eliminate unwanted adverse effects, mainly sedation
- Work peripherally to block the actions of histamine; thus, fewer central nervous system adverse effects
- Longer duration of action (increases compliance with once-daily dosing)
tradition 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, 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, chronic obstructive pulmonary disease, peptic ulcer disease, benign prostatic hyperplasia, or pregnancy.
- Instruct patients to report excessive sedation, confusion, or hypotension.
- Instruct patients to avoid driving or operating heavy machinery; advise against consuming alcohol or other central nervous system depressants.
- Instruct patients not to take these medications with other prescribed or OTC medications without checking with their prescribers.
- Best tolerated when taken with meals; reduces gastrointestinal 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.
nasal congestion
Excessive nasal secretions
Inflamed and swollen nasal mucosa
Primary causes
Allergies
Upper respiratory infection (common cold)
three main types of decongestats
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
oral decongestants
- Prolonged decongestant effects, but delayed onset
- Effect less potent than topical
- No rebound congestion
- Exclusively adrenergics
- Example: pseudoephedrine
topical nasal decongestatnts
- Topical adrenergics
- Prompt onset
- Potent
- Sustained use over several days causes rebound congestion, making the condition worse.
- ephedrine, oxymetazoline, phenylephrine, and tetrahydrozoline
Adrenergics
ephedrine, oxymetazoline
Intranasal steroids
beclomethasone dipropionate (Qvar®), budesonide (Rhinocort®), flunisolide (Rhinalar®), fluticasone (Avamys®), triamcinolone (Nasacort®), mometasone (Nasonex®)
Intranasal anticholinergic
ipratropium (Atrovent®)
inhaled intranasal steriods and anticholinergic drugs
- Not associated with rebound congestion
- Often used prophylactically to prevent nasal congestion in patients with chronic upper respiratory tract symptoms
nasal decongestants(adrenergics) 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.
nassal decongestants 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
nasal decongestants contraindications
Drug allergy
Acute-angle glaucoma
Uncontrolled cardiovascular disease, hypertension
Diabetes and hyperthyroidism
Prostatitis
Inability to close the eyes
History of cerebrovascular accident or transient ischemic attacks
Cerebral arteriosclerosis
Long-standing asthma
Benign prostatic hyperplasia
Diabetes
nsasl decongestatns adverse effects
Adrenergics
Nervousness
Insomnia
Palpitations
Tremors
Steroids
Local mucosal dryness and irritation
(Systemic effects caused by adrenergic stimulation
of the heart, blood vessels, and central nervous system)
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.
Methyldopa
Urinary acidifiers and alkalinizers
Patients should avoid caffeine and caffeine-containing products.
Patients should report a fever, cough, or other symptoms lasting longer than 1 week.
Monitor for intended therapeutic effects.
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
two basic types of cough
Productive cough: congested; removes excessive secretions
Nonproductive cough: dry cough
coughing
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.
antitussives
Drugs used to stop or reduce coughing
Opioid and nonopioid
Primarily used only for nonproductive coughs!
May be used in cases when coughing is harmful
antitussives mechanism of action
Opioids
Suppress the cough reflex by direct action on the cough centre 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
Nonopioids
Dextromethorphan: works in the same way
Not an opioid
No analgesic properties
No central nervous system depression
antitussive indications
Used to stop the cough reflex when the cough is nonproductive or harmful
antitussives contraindications
Drug allergy
Opioid dependency
Respiratory depression
Others
antitiussives adverse effects
diphenhydramine:
Sedation, dry mouth, and other anticholinergic effects
dextromethorphan
Dizziness, drowsiness, nausea
Opioids
Sedation, nausea, vomiting, lightheadedness, constipation
anititussive nursing implaications
Perform respiratory and cough assessment, and assess for allergies.
Because of possible sedation, drowsiness, or dizziness, instruct patients to avoid driving or operating heavy equipment.
Report any of these 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.
anititussive nursing implaications
Perform respiratory and cough assessment, and assess for allergies.
Because of possible sedation, drowsiness, or dizziness, instruct patients to avoid driving or operating heavy equipment.
Report any of these 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.
expectorants
Drugs that aid in the expectoration (removal) of mucus
Reduce the viscosity of secretions
Disintegrate and thin secretions
Example: guaifenesin
expectorants mechanism of action
Reflex stimulation
Irritation of the gastrointestinal 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
expectorants drug effects
By loosening and thinning sputum and bronchial secretions, the tendency to cough is indirectly diminished.
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
expectorants nursing implications
Expectorants should be used with caution in older adults and patients with asthma or respiratory insufficiency.
Patients taking expectorants should receive more 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.
