Antihistamine Flashcards
Common Cold Causes?
How do they invade?
Most are caused by viral infection (rhinovirus or influenza virus).
Virus invades tissues (mucosa) of upper respiratory tract, causing upper respiratory infection.
What does the Common cold from virus invasion produce?
Cold symptoms?
Excessive mucus production results from the inflammatory response to this invasion (of the viruses).
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?
Mucosal irritation also causes the release of several inflammatory and vasoactive substances, _______ small blood vessels in the nasal sinuses and causing _________
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 or URI (4)
Involves combined use of antihistamines, nasal decongestants, antitussives, and expectorants
Treatment is ________ only, not _________.
_________ treatment does not eliminate the causative _________.
Treatment is symptomatic only, not curative.
(Can only relieve symptoms)
Symptomatic treatment does not eliminate the causative pathogen.
Difficult to identify whether cause is ___ or ____
Treatment is “________” treating the most likely cause
______ and ______ may be used, but a definite viral or bacterial cause may not be easily identified.
Natural health products examples and benefits
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.
Natural health products- vitamin C, echinacea, goldenseal- prevent onset of cold symptoms/ decrease severity
In 2009, Health Canada issued recommendations that over-the-counter (OTC) cough and cold products not be given to children younger than __ years of age.
Not effective in small children, and parents are advised to consult their pediatrician on the best ways to manage these illnesses.
6
OTC cough and cold products are not to be given to children younger than 6 due to sedation, seizures, hallucinations, tachycardia and abnormal heart rhythms
Histamines
5 functions
Histamine is a major?
involved in nerve impulse transmission in the CNS
DILATION of capillaries
CONTRACTION of smooth muscle
STIMULATION of gastric acid secretions
ACCELERATE HR
Histamine is a major inflammatory mediator in many allergic disorders, such as rhinitis, anaphylaxis, angioedema, drug fevers, insect bite reactions and urticaria (pale red, raised, itch bumps)
Histamine 1 (H1) receptors
mediate smooth muscle contraction and dilation of capillaries
H2 receptors
mediate acceleration of HR and gastric secretion
Excessive amounts of histamine can cause?
anaphylaxis and severe allergic symptoms
Anaphylaxis and severe allergic 3 symptoms
constriction of smooth muscles in the stomach and lungs
increase in body secretions
vasodilation and increased capillary permeability results in the movement of fluid out of the BVs and into the tissues, causing a drop in BP and edema
Antihistamines [histamine antagonists]
directly compete with histamine for receptor sites
H1 blockers/ H1 antagonists
H1 antagonists drugs
Medications
Treats?
Loratadine and Diphenhydramine
Treats nasal allergies (seasonal hay fever)
Relieves symptoms of the common cold: sneezing and runny nose (can alleviate symptoms but not destroy the virus)
Palliative but not curative
has varying degrees of antihistaminic, antichollinergic, and sedating properties
treats allergies, vertigo, motion sickness, insomnia, and cough
Antihistamines competes with?
Also affects?
histamine for the H1 receptors in the smooth muscle surrounding BVs and bronchioles
secretions of the lacrimal, salivary, and respiratory mucosal glands: primary antichollinergic effects of antihistamines
Loratadine and Diphenhydramine MECHANISM OF ACTION
Compete with histamine for specific receptor sites (Histamine Antagonist)
-Bind to histamine receptors on mast cells & basophils
-Prevent further release of histamine & actions
H1 BLOCKERS or H1 antagonists (known as antihistamines)
- ASSOCIATED WITH
- LOCATION
H1 blockers are associated with antihistamines
H1 are in areas such as smooth muscle surrounding blood vessels and bronchioles
Loratadine and Diphenhydramine
H1 antagonists drugs
also cause ____ effects
Also affects secretions of lacrimal, salivary and respiratory mucous glands which are the primary anticholinergic actions (dry mouth, etc.) of antihistamine
Antihistamine mechanism of action
during an allergic reaction, histamines are released from mast cells and basophils in response to an antigen in blood.
Histamine then binds and activates other cells in the nose, eyes, respiratory tract, GI tract, and skin producing allergy symptoms
In the respiratory tract, histamine causes extravascular smooth muscle (bronchial tree) to contract (while antihistamines cause it to RELAX)
Histamine can cause pruritus by stimulating nerve endings (antihistamine can alleviate itching)
circulating histamine binds to histamine receptors on basophils and mast cells which further stimulates the release of histamine
Antihistamine blocks histamine receptors on surfaces of basophils and mast cells and prevents the release and action of histamine
They do not remove histamine already bound but compete for the unoccupied receptors
(better if given early in a histamine-mediated reaction before all histamine binds to cell membrane receptors)
consequences of histamine binding are?
vasodilation
increased GI, respiratory, salivary, and lacrimal secretions
increased capillary permeability with edema
Binding of H1 blockers (antihistamines) to these receptors PREVENTS?
Vasodilation
increased GI, respiratory, salivary, and lacrimal secretions
Increased capillary permeability with resulting edema
The allergen binds to antibodies— causes HISTAMINE SECRETION:
- swelling of BVs and releasing of fluids
- congestion—insufficient 02—sleepiness, weakness, drowsiness, snoring, headache
OR
- swelling of BVs and releasing of fluids
- nasal irritation—infection/ inflammation—sinusitis, asthma, inflammation of middle ear
ANTIHISTAMINES INDICATION
nasal allergy
seasonal/ perennial allergic rhinitis
common cold
allergic reactions
motion sickness
PD(due to antichollinergic effects)
Vertigo
Sleep aids
Antihistamines action
Mediate’s inflammatory response:
Rhinitis: hay fever, mold, dust
Anaphylaxis
Angioedema
Drug fevers
Insect bite reactions
Urticaria (itching)
Symptoms of common cold
-sneezing
-Runny nose
The anithistaminic, anticholinergic and sedative properties also make them useful for treatment of:
Vertigo
Insomnia
Motion sickness
cough
Antihistamines are most effective when
Most effective when given early in histamine mediated reactions
Antihistamines should not be used as sole therapy in?
Should not be used as sole therapy in acute asthma attacks
Antihistamines Contraindication
Narrow angle glaucoma
Heart disease
Hypertension
COPD
Peptic ulcer disease
Seizure disorders,
BPH (enlarged prostate)
pregnancy
NOT to be used as sole therapy for asthma attack
Pediatric Alert
______ is not recommended in children under 6 yrs
______ is not recommended in children
______is not recommended in children under 2 yrs
Fexofenadine (Allegra) is not recommended in children under 6yrs
Desloratadine (Aerius) is not recommended in children
Loratadine (Claritin) is not recommended in children under 2 yrs
Recommend to discontinue antihistamine at least 4 days prior to allergy testing
Antihistamines Adverse Effects
Drowsiness (varies amongst drug class)
Sedative effects
“Drying” effects
Dry mouth
Difficulty urinating
Constipation
Change in vision
Cardio: dysrhythmias, hypotension, palpitations, syncope, sedation, dizziness, muscular weakness, excitement, nervousness, seizures
GI: N & V, diarrhea, constipation, hepatitis
Antihistamines Interactions
Medications
Food
Loratadine drug interactions: Ketoconazole, cimetidine and erythromycin increase concentrations of fexofenadine & loratadine
Diphenhydramine: Alcohol, CNS depressants, MAOs increase depressant effects of cetirizine (Reactine) and diphenhydramine (Benadryl)
Cardiovascular small blood vessels
Histamine effects- dilates BVs, increases BVs permeability (allow substances to leak into tissues)
Antihistamine effects: reduces dilation of BVs
Smooth muscle exocrine glands
Histamine: stimulate salivary, gastric, lacrimal, and bronchial secretions
Antihistamine: reduces salivary, gastric, lacrimal, and bronchial secretions
Immune
Histamine effects- released from mast cells; results in allergic reaction
Antihistamine: does not stabilize mast cells/ prevent the release of histamine; but does bind to histamine receptors and prevents the action of histamine
Nonsedating antihistamines medications
Function
Loratadine
cetrizine
fexofenadine
eliminate many adverse effects, esp. sedation
Act peripherally to block actions of histamine and therefore have significantly less CNS effects
also called peripherally acting antihistamines because they do not readily cross blood-brain barrier
has a longer duration of action
Loratadine:
Drug class?
nonsedating antihistamine [takken OD]
does not distribute to CNS which diminishes sedative effects
High doses can cause drowsy, headache, and fatigue
relieves seasonal allergic rhinitis (hay fever) and chronic urticaria
CONTRA: allergy
Traditional antihistamines
works both peripherally and centrally
has antichollinergic effects, which in some cases is more effective than non-sedating antihistamines
diphenhydramine, dimenhydrinate
used alone/ in combination
treats nausea/ motion sickness
causes drowsiness
Diphenhydramine hcl
acts peripherally and centrally
antichollinergic and sedative effects
used as a hypnotic drug because of its sedating effects
Not for OAs due to the risk of falls [hangover effects]
the greatest range of therapeutic indication
relief/ prevention of allergies, motion sickness, treatment of PD, and promotes sleep
used in conjunction with EPi for anaphylaxis and treats dystonia
CONTRA: allergy
CAUTION: nursing mothers, newborns, lower respiratory tract symptoms
Nasal Congestion
Excessive nasal secretions
Inflamed and swollen nasal mucosa
Primary causes: Allergies & Upper respiratory infection (common cold)
Decongestants
Three separate groups of nasal decongestants:
taken orally to prevent system effect (prolonged effects and delayed onset), inhaled/ topically into the nose
adrenergic (sympathomimetics)
anticholinergic (parasympatholytic)
corticosteroids (intranasal steroids)
Decongestants
ORAL route
NASAL
prolonged decongestant effects, onset is delayed and effect is less potent than topical
Nasal- can cause rebound congestion because of the rapid absorption of the drug through mucous membranes followed by a rapid decline in effectiveness
Adrenergics (sympathomimetics) medications 2
Pseudoephedrine (Sudafed) oral
**Oxymetazoline HCl (Dristan) nasal spray
Anticholinergics (parasympatholyitcs)
Ipratropium bromide (Atrovent) nasal spray
Corticosteriods medications
Fluticasone propionate (Flonase) nasal spray
Beclomethasone dipropionate (Rivanase) (nasal spray)
Budenoside (Pulmicort, pulmicort turbohaler, symbicort turbohaler)
Decongestants mechanism of actions
shrink engorged nasal mucous membranes and relive nasal stuffiness
Adrenergics (sympathomimetics) mechanism of action
Constrict small arterioles (BVs around nasal sinuses)
(when BVs are stimulated by adrenergic drugs- they constrict)
Once BVs shrink, the nasal secretions in the swollen mucous membrane are better able to drain
Corticosteriods mechanism of action
Target inflammatory response elicited by invading organisms/ antigen; the body responds to invaders by producing inflammation to isolate area and call other cells to destroy invader
Steroids exert anti-inflammatory effects by causing cells to be turned off/ rendered unresponsive
“turn off” cell response; reduce inflammatory symptoms to improve patient comfort and air exchange
Anticholinergics action
Inhibits secretions of the serous and serous-mucous membranes of the nasal passages
Decongestant indications
acute/ chronic rhinitis
common cold
sinusitis
hay fever
allergies
reduces swelling of nasal passages before surgery
Decongestants
Contraindications of adrenergic drugs
Narrow angle glaucoma
Uncontrolled cardiovascular disease
Hypertension
Diabetes
Hyperthyroidism
Prostatitis, BPH
Inability to close eyes (stroke patients)
TIAs
Asthma
Drugs allergy
Adverse effect of Adrenergics (think adrenergic stimulation)
Nervousness
Insomnia
Palpitations
Tremor
AE of Corticosteriods
Localized dryness, nose bleeds, mucosal thinning
AE of anticholinergic
Also excessive dryness, nose bleeds
MAOIs may result in additive pressor effect with ______ decongestants
MAOIs may result in additive pressor effect with adrenergics decongestants- raise BP
systemic sympathomimetic drugs when combined with sympathomimetic nasal decongestant
cause drug toxicity
Antitussives
Inhibition of cough reflex
Cough reflex
stimulated when receptors in the bronchi, alveoli, and pleura are stretched
Antitussives indication
Prevent harm: post surgical injury (abdominal incision)
Reduce respiratory distress in non-productive “dry cough” situations
Antitussives
Two opioid
Codeine phosphate controls cough, potentially addicting, risk for CNS and respiratory depression
Hydrocodone
suppress cough reflex
if taken as prescribed, does not lead to dependency
Antitussives
Two Nonopioid
Dextromethorphan hydrobromide
Diphenhydramine
less effective than opiod
Opioid antitussives
how do they supress cough reflex?
other effects (two)
Suppress cough reflex through direct action on the cough centre in the medulla
Provide analgesia
Drying effect on mucosa (increase mucous viscosity) helps to reduce runny nose and postnasal drip
Non opioid antitussives action
Suppress cough reflex through direct action on the cough centre in the medulla
Drying effect on mucosa (increase mucous viscosity) helps to reduce runny nose and postnasal drip
**No Analgesia and does not cause CNS depression
Antitussives indication
Stop cough reflex
Antitussives Contraindications
Opioid dependency, respiratory depression (older adults)
—–Alcohol use, CNS depression, anoxia, hypercapnia, COPD, respiratory depression, increased intracranial pressure, impaired kidney & liver function
Dextromethorphan: hyperthyroidism, cardiac disease, hypertension, glaucoma, MAOIs (does not cause respiratory or CNS depression)
Antitussives Adverse Effects:
Codeine/ hydrocodone
Dextromethorphan
Diphenhydramine
Codeine/ hydrocodone-Sedation, nausea, vomiting dizziness, constipation
Dextromethorphan- dizzy, drowsy, and nausea
Diphenhydramine- sedation, dry mouth, antichollinergic effects
Antitussives Interactions
Opioids: May potentiate other opioids, general anesthetics, tranquillizers, sedatives, hypnotics, TCAs, MAOIs, alcohol
Dextromethorphan: may potentiate MAOIs
Dextromethorphan:
unsafe for children under?
contraindications
unsafe for children under 6
nonopioid
safe and non-addicting
Not addictive/does not cause CNS or respiratory depression
contraindications: allergy, asthma, emphysema/ persistent headache
Codeine
not for children under
opioid antitussive
control cough
potentially addictive and can depress respiration
not for children under 12
Expectorants
Aid in expectoration (coughing up & spitting out) of excessive mucous in UR tract by breaking down and thinning out the secretions
reduces the viscosity of secretions
Indication: relief of productive cough, decreased tendency of cough
AE: minimal; nausea, vomiting, gastric irritation
Expectorants- Most common and available in Canada is?
guaifenesin-decrease mucus related symptoms; manages cough
beneficial in the treatment of productive coughs because it thins the mucus in the respiratory tract that is difficult to cough up
Expectorants
MoA -Reflex stimulation (controversial and varied thought)
– loosening and thinning of the respiratory tract secretions occurs in response to an irritation of the GI tract produced by the drug – [vagal pathway]
MoA – UR secretagogues
loosening and thinning by way of direct stimulation of secretory glands to release secretagogues that increase hydration of secretions and “unstick” them from airways. DOES NOT INCREASE MUCUS SECRETION.
Expectorants
are defined as medications that improve the ability to expectorate purulent secretions. This term is now taken to mean medications that increase airway water or the volume of airway secretions, including secretagogues that are meant to increase the hydration of luminal secretions (eg, hypertonic saline or mannitol) and abhesives that decrease the adhesivity of secretions and thus unstick them from the airway (eg, surfactants). Expectorants do not alter ciliary beat frequency or mucociliary clearance. Oral expectorants were once thought to increase airway mucus secretion by acting on the gastric mucosa to stimulate the vagus nerve, but that is probably inaccurate.
Expectorants indications
Used for relief of productive cough associated with common cold, bronchitis, laryngitis, pharyngitis, pertussis, influenza, measles
Expectorants contraindications
Contraindicated if allergic and in case of hyperkalemia (for K+ containing expectorants)
Cont use with alcohol/ diuretics
Expectorants AE
Interactions
No big issues with adverse effect (possible nausea, vomiting, gastric irritation)
No big issues with interactions
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
Drug of choice is based on?
type and sevrity of symptoms
Nursing Considerations
Teach non-pharm measures and dangers of using OTC meds
Please read Natural Health Products and know about use of vitamin C, echinacea, and goldenseal for colds/flus/immune system booster
Please understand issues for older adults and people with asthma & chronic respiratory disease
Teach patients about signs and symptoms of infectious complications (secondary bacterial infections, symptoms of other infectious diseases development such flu) & to seek medical help
Adrenergics
drugs that stimulate sympathetic nerve fibers of autonomic NS that use Epinephrine and NE neurotransmitters
Antichollinergics
Blocks ACh; results in the inhibition of parasympathetic nerve impulses
Antigens
substances capable of inducing specific immune responses
Antihistamine
can reduce physiological and pharmacological effects of histamines
Antitussives
drugs that reduce coughing
Corticosteroids
carbohydrate and protein metabolism, maintenance of glucose levels, electrolyte and water balances, cardiovascular, skeletal, kidneys and other system functions
Decongestants
reduce congestion and swelling
Emperical therapy
treats disease based of observations and experience, rather than knowledge/ precise cause
Expectorants
increase the flow of fluids in the respiratory tract by reducing the viscosity of secretions and facilitate removal by coughing
Nosedating antihistamines
works peripherally to block histamine, NO CNS effects
do not cross blood-brain barrier
eliminate sedation
Loratadine, cetrizine
Sympathomimetic drugs
mimic those resulting from the stimulation of sympathetic NS
Allergic reaction symotoms
hives
wheezing
bronchospasms
tachycardia
hypotension
different when treating influenza/ cold
Fexofenadine hcl drug interactions
erythromycin and other CYP450 inhibitors= increased histamine levels
phenytoin= decreased fexofenadine levels
Loratadin drug interactions
antifungals, cimetidine and erythromycin= increased antihistmaine levels
diphenhydramine and cetrizine with alcohol can cause
increased CNS depressant
CONCERN: use of antihistamines with acute asthma attacks and lower respiratory tract infection (pneumonia)
Rationale: antihistamine dry up secretions, if the pt cannot expectorate secretions, secretions may become viscous, occlude airways and lead to atelectasis, infection/ occlusion of bronchioles
decongestant may increase
BP and HR so vital signs need to be assessed
PPL with HTN can use topical decongestant short term; against oral decongestant
CAD- use of decongested must be avoided
OTC cough and cold drugs
associated with oversedation, seizures, tachycardia, death
decongestant contraindication
acute angle glaucoma
cardiovascular disease
HTN
diabetes
prostatitis
topically applied decongestant- may be absorbed in the circulation > Excessive usage can cause cardiovascular effects
monitor for paradoxical reactions
frequent use can lead to rebound nasal congestion
Does H1 receptor antagonist drug cross blood brain barrier?
NO
DRY mouth from antihistamine
mouth care, candy, OTC cold lozanges, chew gum
AE of antitussives
drowsiness/ dizziness; caution when driving/ doing activity that requires alertness
If an antitussive contains codeine- may increase the risk of CNS and respiratory depressant
report symptoms of pneumonia from taking antitussives: fever, chest tightness, colored sputum, difficulty/ noisy breathing, activity intolerance/ weakness
Expectorants contraindication
avoid alcohol
not use drugs longer than. a week
H1 blockers
antihistamine
prevent harmful effects of histamine and treat rhinitis, anaphylaxis reactions to insect bites,
H2 blockers
treat gastric acid disorder, ulcer disease, hyperacidity
decongestant
constriction of engorged and swollen BVs in the sinuses decreases pressure and allow the mucous membrane to drain
AE- palpitation, insomiinsomniana, restlessness, nervousness
Non opiod antitussives
may also cause sedation, drowsiness or dizziness (large and frequent doses)
DO not drive/ avoid alert activities
Codeine containing antitussives
may cause CNS depression, do not give with alcohol
fexofenadine with erythromycin/ CYP450 inhibitors
leads to increased antihistamine levels
fexofenadine with phenytoin
leads to decreased fexofenadine level
loratadine given with antifungals , cimetidine, and erythromycin
leads to increased antihistamine level
diphenhydramine and cetrizine with alcohil, MAOIs, and CNS depressants
increased CNS depression
Why not use antihistamine in people with acute asthma attack or have lower respiratory disease?
dry up secretions
if the patient cannot expectorate secretions, the secretions may become viscous (thick), occlude airways and lead to atelectasis, infection, or occlusion of the bronchioles
Antihistamine in OAs
result in paradoxical reactions; subsequent irritability, dizziness, confusion, sedation, and hypotension
Decongestant may affect
May also affect
functional structures of eyes and nose (eyedrops/ nasal spray)
BP and HR- monitor vitals
PT with HTN can use topical decongestant short term, advised against using oral decongestant
CAD- avoid decongestant
Decongestant contraindication
glaucoma
allergy
diabetes
prostatitis
adrenergic decongestant
may increase BP (cardio effects)
dizziness, nervousness, headache (CNS effects)
Inhaled intranasal steroids are contraindicated in?
pt with nasal mucosal infection or allergy
Antitussive therapy
assess safety- can cause sedation
Respiratory assessment
include rate, rhythm, and depth as well as breath sounds, presence of cough and sputum
Reduced dosages for
those with kidney impairment
Fluids
Helps liquefy secretions, assist in breaking thick secretions and makes it easier to cough up secretions (encourage fluid intake)
Which medication causes rebound congestion from overuse/ dependence?
Oxymetazoline HCl (Dristan) nasal spray
Ekenasia
does not prevent colds, reduce cold symptoms and reduce recovery time
Golden seal
treats upper resp disease, antibacterial, fungal or protozoal
Avoid alcohol in pts taking?
expectorants, and do not use for longer than 1 week
H1 blockers
antihistamine
prevent harmful effects of histamine and used to treat seasonal allergic rhinitis, anaphylaxis, reactions to insect bites
H2 blockers
treats gastric acid disorder, hyperacidity/ ulcer
Decongestant
cause constriction of the engorged and swollen BVs in the sinuses, which decreases pressure and allows mucous membranes to drain
AE: heart and CNS stimulating effects- palpitations, restlessness, nervousness
Non-opioid antitussives may also cause
sedation, drowsiness, and dizziness. DO not drive/ engage ifr metal alertness required
Possible contraindication for a decongestant
glaucoma
decongestant has an adrenergic stimulating effect that may result in?
hypertension
drug to use for a pt with bronchitis with a productive cough?
expectorant
antitussive cough medication is for patients with
a patient who has had a recent abd surgery
adverse effect of decongestant
heart palpitations
antihistamine adverse effects
dizziness, hang over effect, drowsiness, dry mouth
dextromethorphan is for?
cough
