Antihistamine Flashcards
Adrenergics
- sympathomimetic
-stimulate the sympathetic nerve fibers of the ANS
-Use epinephrine or epinephrine-like substances as neurotransmitters.
Antagonists
- Causes opposite action of a drug
- Or compete for receptor sites
Antihistamines
Reduces the effects of histamine
Antitussive
- Reduces coughs
- Inhibits neural activity in cough center of CNS
Decongestants
- reduce congestion or swelling,
- in upper or lower respiratory tract.
Empiric therapy
Expectorants
- increase the flow of fluid in the respiratory tract
- By reducing the viscosity of secretions
- Facilitate their removal by coughing
Cause of Common colds
Caused by: Viral infections (Rhinovirus or Influenza virus)
- The invade the tissue (mucosa) of the upper respiratory tract (nose, pharynx, larynx)causing upper respiratory tract infection (URI)
- Stimulates excessive mucus production
- Leads to symptoms of a cold: sore throat, coughing, upset stomach - Irritation of nasal mucosa causes a sneeze reflex
-Release of inflammatory and vasoactive substances
-Dilation of small blood vessels
-Nasal congestion
4 Treatment of the Common Cold symptoms
Antihistamines
Nasal decongestants
Antitussives
Expectorants
These drugs can only ______ symptoms of a URI, the do nothing to ________
- relieve
-eliminate the pathogen
Empiric therapy
The treatment is based on what is believed to be the cause of the symptoms
Antihistamines are drugs that
directly compete with histamine for specific receptor sites
Therapeutic effect of Antihistamines
Nerve impulse transmission in the CNS
Dilation of capillaries
Contraction of smooth muscles
Stimulation of gastric secretion
Increase HR
Types of Histamine receptors
- H1: Histamine 1 receptors: mediate smooth muscle contractions and dilation of capillaries (vasodilation)
- H2: Histamine 2 receptors: mediate acceleration of HR and gastric acid secretions
- Increases gastric secretion that leads to peptic ulcers. Give it to people who have gastric issues.
H1 antagonist
H1 antagonist: Antihistamines
Drugs that end with -Ine
Chlorpheniramine
Fexofenadine (Allegra)
Loratadine (Claritin)
Cetirizine (Zyrtec)
Diphenhydramine (Benadryl)
Used to treat:
- Nasal Allergies
- Seasonal hay fever
Relieves the symptoms of common viral cold
- Sneezing
- Runny nose
Person experiencing Anaphylaxis you give what drug first _____ because it has a _____ effect
Benadryl
Sedative
H2 antagonist: H2 blockers
Drugs that end with -ine
Cimetidine (Tagamet)
Ranitidine (Zantac)
Famotidine (pepcid)
Nizatidine (Axid)
Used to reduce gastric acid in peptic ulcer disease
Antihistamine MOA
All antihistamine compete with histamine for the H1 receptors in the smooth muscles.
- Work by blocking the histamine receptors on the surface of basophils and mast cells
- Preventing the release and actions of histamine stored within the cells
- Do not push histamine already bound to receptors but compete for the unoccupied receptors.
- Preventing vasodilation, increase GI, respiratory salivary, lacrimal secretions and increased permeability with edema.
Cardiovascular (small blood vessels) Antihistamine vs histamine
Histamine effects: Dilates BV, increases BV permeability causing edema
Antihistamine effects: Reduces dilation of BV and decreases permeability
Smooth muscle (on exocrine glands) Antihistamine vs histamine
Histamine effects:Stimulates salivary gastric , lacrimal and bronchial secretions
Antihistamine effects: Reduces delivery gastric, lacrimal and bronchial secretions
Immune system (release of substances commonly associated with allergic reactions) Histamine vs Antihistamine
Histamine effects:Released from mast cells resulting in allergic reactions
Antihistamine effect: Binds to histamine receptors and prevents the actions of histamine
Antihistamine indications
Manage/ relieve symptoms of
- nasal allergies
- Seasonal or perennial allergic rhinitis (hay fever)
- Urticaria (hives)
- Typical symptoms of common colds
Treatment of
- Allergic reactions
- Motion sickness
- Parkinson disease (anticholinergic effects)
- Vertigo (spinning sensation)
Antihistamines: Contraindications
Known drug allergy
- narrow - angle glaucoma
- Cardiac and kidney disease
- Bronchial asthma
- COPD
- Hypertension
- Caution in patients with impaired liver or renal insufficiencies, lactating mothers
Antihistamine Adverse effects
- Drowsiness
- Anticholinergic drying effect
- Dry mouth
- Changes in vision
- Difficulty urinating
- Constipation
Traditional antihistamines work both
- Peripherally and Centrally
- Cause them to be more effective
Tradition Antihistamines are used alone or in combination with other drugs for
Insomnia or motion sickness
Diphenhydramine (benadryl)
Traditional Antihistamine
- Anticholinergic and sedative effects
Used for: relief or prevention of histamine-mediated allergies, motion sickness, treatment of parkinson’s disease, promotion of sleep, anaphylaxis
Contraindications/ Cautions: nursing mothers, neonates, pt with lower respiratory tract problems, elderly (risk for falls)
Nonsedating Antihistamine Work
peripherally to block the actions of histamine do not cross blood brain barrier,
Nonsedating antihistamines have ___ durations of action compared to traditional antihistamines
Longer
Loratadine (Claritin)
Non-sedating Antihistamine
Used for: relieve the symptoms of seasonal allergic rhinitis (hay fever), urticaria
Active metabolite: Desloratadine
Contraindication: Drug allergy
Antihistamine Nursing Implications
Instruct patients to report ?
-Adverse effects: Drying effects: Dry mouth, changes in vision, urinary retention, constipation
- Instruct patients to avoid driving or operating heavy machinery
- Instruct patients not to take these medications with other prescribed or OTC unless they were previously approved by prescriber
GI upset, how do you take?
- Taken with meals to minimize GI upset
What do you do for dry mouth?
- Chew, suck on candy or chew gum, perform frequent mouth care to ease dryness
Traditional Antihistamine Assessment/ implementation
- Best taken with meals
- Pt experiences dry mouth teach the pt to chew or suck on candy and perform frequent mouth care
-Should not be take with other OTC cough or could medications - Concern in use of drug in patients with
- acute asthma attack, LRI, Pneumonia
Nasal congestion: define, cause
- Due to excessive nasal secretion
- Inflamed and swollen nasal mucosa
- Common cause: allergies and URIs (common colds)
Types of Decongestants
Adrenergics (largest group)
- sympathomimetics
Anticholinergics
- Less commonly used
- Parasympatholytics
Corticosteroids
- Topical, intranasal steroids
Routes of Decongestant
PO: Produce prolonged systemic decongestant effects
Nasal:Produce a more rapid effect can also cause rebound congestion
- Rebound congestion occurs if repeated use of decongestant causing a rapid absorption leading to decline in therapeutic effect
- Teach patient to limit their usage to 3 day bc it won’t be as effective and can least to rebound congestion
Nasal Decongestants MOA:
Adrenergic drugs
Shrink engorged nasal mucous membranes and relieve nasal stuffiness
- Constricting small arterioles BV surrounding the nasal sinuses
- Once these BV shrink the nasal secretions in swollen mucous are able to drain through nostrils or lymphatic circulation
- Referred to as sympathomimetics because of their ability to stimulate the PNS
Nasal steroids
Aimed to treat inflammatory response caused by invading organisms (viruses, bacteria, antigens)
Steroids stimulate their antiinflammatory effect by reducing inflammatory symptoms
Nasal Decongestants: Adverse Effects
- Adrenergics
- Nervousness
- Insomnia
- Palpitations
- Tremors
(Systemic effects caused by adrenergic stimulation of the heart, blood vessels, and CNS)
Nasal Decongestants: Adverse Effects
- Steroids
Local mucosal dryness
Irritation
*Teaching
Nasal decongestants- Contraindications/ Cautions
Narrow angled glaucoma
Uncontrolled CVD
HTN
Diabetes
Hyperthyroidism
Nasal Decongestant Interactions
Systemic sympathomimetic drugs and sympathomimetic nasal decongestant cause toxicity when used together
MAOI - additive pressor effect , increase BP
Nasal Decongestant Patient teaching
-Only take the medication as ordered (does & frequency)
- Excessive use of nasal inhaled decongestants may lead to rebound congestionnasal passages become more congested as the effects of the drug wear off.
- Advise the patient to report to the prescriber any excessive dizziness, heart palpitations, weakness, sedation, or excessive irritability.
Decongestant Nursing assessments and Implementations
- Generally used for nasal congestion
- Increase pt taking decongestant fluid intake to 3000 ml per day
-Fluid helps liquefy secretions , breaking up secretions
-Excessive use can lead to rebound congestion can cause cardiovascular effects such as increase in blood pressure and CNS stimulation with headache, nervousness, or dizziness.
Decongestant drugs
End with -ine
Oxymetazoline (Afrin)
Zidovudine (Flonase)
Antihistamine drugs
Loratidine (Claritin)
Diphenhydramine (Benadryl)
The Goal of nasal steroids is to
reduce the inflammatory symptoms to improve patient comfort and air exchange.
Oxymetazoline (Afrin)
Sympathomimetic
Alpha adrenergic vasoconstrictor
- Used to relieve nasal congestion
- Vasoconstriction : dilate the arteries , reducing nasal blood flow and congestion’
Antitussives
Used for: Drugs used to stop or reduce coughing
Types: Opioid and nonopioid
Opioid: Codeine, hydrocodone
Nonopioid: Dextromethorphan, Benzonatate
Used only for nonproductive coughs!
May be used in cases when coughing is harmful
Antitussives: Mechanism of Action Opioids
Drugs:Codeine, hydrocodone:
- Suppress the cough reflex through direct action on the cough center in the CNS (medulla)
- Provide analgesia and have drying effect on mucosa of respiratory tract
- Increases viscosity of respiratory secretions
- Reducing runny nose, postnasal drip
Nonopioids
Drugs:Dextromethorphan, Benzonatate
- Suppress the cough reflux through direct action on cough center
- Does not have analgesia effects or does not cause CNS depressions
Antitussives: Indications
Used to stop the cough reflex when the cough is nonproductive or harmful
Antitussives: Contraindications: Opioids
Opioid dependency
Respiratory depression
Opioids: Codeine and Hydrocodone
Alcohol use
CNS depression
Renal and lIver disease
COPD
Antitussives: Contraindications:Non Opioids
Nonopioids: Dextromethorphan
MAOIs - stop taking within 14 days
Hypertension
CVD
Antitussives Adverse effects
Benzonatate: dizziness, headache,pruritus, sedation
Codeine and hydrocodone: sedation, nausea, vomiting, lightheadedness, constipation
Dextromethorphan: Dizziness, drowsiness, nausea
Diphenhydramine: sedation, dry mouth, anticholinergic effects
Antitussives:Nursing Implications
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.
Benzonatate - non opioid antitussive drug
Used to numb the cough receptors
Codeine- opioid antitussive drug
Used: To control coughs
Potentially addictive and can depress respiration, CNS depressant effects
Contraindicated: respiratory depression, increased icp, seizure disorders, respiratory disorders
Dextromethorphan- non opioid antitussive drug
Used to control coughs
Non addictive and does not cause respiratory or CNS depression
Contraindicated: asthma, emphysema, persistent headache
Expectorants
- Drugs that aid in the expectoration (removal) of mucus in the respiratory tract
- Reduce the viscosity of secretions (sputum)
- Most common expectorants: Guaifenesin
MOA Expectorants
- Guaifenesin: increasing the hydration of the respiratory tract,
- Maintaining sol layer
- Needed for ciliary clearance and reducing viscosity of mucus
- Facilitates the removal of mucus
Guaifenesin MOA
increasing the hydration of the respiratory tract,
Expectorants Indication
Relief of productive coughs
-Commonly associated with common colds, bronchitis, laryngitis,pharyngitis, pertussis, influenza, measles
Suppression of coughs caused by chronic paranasal sinusitis
-Diminishing the tendency to cough
Expectorants Adverse effects
Nausea
Vomiting
Gastric irritation
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.
