Antihistamines, antitussives, decongestants, expectorants Flashcards
What are Antihistamine (H1 antagonist) properties?
Antihistamines have several properties:
1) Antihistaminic
2) Anticholinergic
3) Sedative
What are some contraindications for Antihistamines?
1) Known allergy
2) Glaucoma
3) Cardiac disease (Htn)
4) Kidney disease
5) COPD
What are some of the benefits and uses of intranasal steroids and anticholinergics? Medication names?
Intranasal steroids & anticholinergics:
1) Not associated with rebound congestion.
2) Often used prophylactically to prevent nasal congestion in patients with chronic upper respiratory tract symptoms.
*Intranasal steroids: Beclomethasone dipropionate (Beconase), budesonide (Rhinocort), flunisolide (Nasalide), fluticasone (Flonase), triamcinolone (Nasacort), ciclesonide (Omnaris).
*Intranasal anticholinergic: Ipratropium (Atrovent)
Adverse effect of antihistamines?
1) Anticholinergic (drying) effects, most common.
Dry mouth
Difficulty urinating
Constipation
Changes in vision.
2) Drowsiness; Mild drowsiness to deep sleep.
What are the indications of antihistamines?
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!
What is the mechanism of action for antihistamines?
Used for:
1) Vasodilation
2) Increased GI and respiratory secretions
3) Increased capillary permeability
Block action of histamine at the H1 receptor sites
Compete with histamine for binding at unoccupied receptors. Cannot push histamine off the receptor if already bound.
More effective in preventing the actions of histamine rather than reversing them so it should be given early in treatment, before all the histamine binds to the receptors.
The binding of H1 blockers to the histamine receptors prevents the adverse consequences of histamine stimulation
Nursing implications of antihistamines?
Gather data about the condition or allergic reaction that required treatment; assess for drug allergies.
Contraindicated in the presence of acute asthma attacks and lower respiratory diseases, such as pneumonia.
Use with caution in increased intraocular pressure, cardiac or renal disease, hypertension, asthma, COPD, peptic ulcer disease, BPH, 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 CNS depressants.
Instruct patients to not take these medications with other prescribed or OTC medications without checking with prescriber.
Best tolerated when taken with meals—reduces GI upset.
If dry mouth occurs, teach patient to perform frequent mouth care, chew gum, or suck on hard candy (preferably sugarless) to ease discomfort.
Monitor for intended therapeutic effects.
Effects of oral decongestants?
Prolonged decongestant effects, but delayed onset
Effect less potent than topical.
No rebound congestion.
Exclusively adrenergics;
Example: pseudoephedrine (Sudafed).
Effects of topical decongestants?
Topical adrenergics: Prompt onset; Potent.
Sustained use over several days causes rebound congestion, making the condition worse.
Ephedrine, phenylephrine, tetrahydrozoline, oxymetazoline.
Adrenergics: phenylephrine (Neo-Synephrine); others.
Histamine vs. Antihistamine Effects?
1) Cardiovascular (small blood vessels)
Histamine effects: Dilation and increased permeability (allowing substances to leak into tissues).
Antihistamine effects: Reduce dilation of blood vessels; Reduce increased permeability of blood vessels.
2) Smooth muscle (on exocrine glands).
Histamine effects: Stimulate salivary, gastric, lacrimal, and bronchial secretions.
Antihistamine effects: Reduce salivary, gastric, lacrimal, and bronchial secretions.
3) Immune system (release of substances commonly associated with allergic reactions).
Histamine effects: Mast cells release histamine and other substances, resulting in allergic reactions.
Antihistamine effect: Binds to histamine receptors, thus preventing histamine from causing a response.
Other Effects.
Skin: Reduce capillary permeability, wheal-and-flare formation, itching.
Anticholinergic: Drying effect that reduces nasal, salivary, and lacrimal gland secretions (runny nose, tearing, and itching eyes).
Sedative: Some antihistamines cause drowsiness.
What are some histamine-mediated disorders (Histamine-inflammatory mediator)?
Allergic rhinitis (hay fever, mold, and dust allergies)
Anaphylaxis
Angioedema
Drug fevers
Insect bite reactions
Urticaria (itching)
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.
Supplements & Herbal Products for common cold?
Vitamin C
Zinc
Echinacea
Goldenseal
What are the two types of antihistamines and what do they do?
1) Traditional Antihistamines: Older; Work both peripherally and centrally.
Have anticholinergic effects, making them more effective than nonsedating drugs in some cases.
Examples: diphenhydramine (Benadryl); chlorpheniramine (Chlor-Trimeton), meclizine, promethazine .
2) Nonsedating/Peripherally Acting Antihistamines:
Developed to eliminate unwanted adverse effects, mainly sedation.
Work peripherally to block the actions of histamine; thus, fewer CNS adverse effects.
Longer duration of action (increases compliance).
Examples: fexofenadine (Allegra), loratadine (Claritin), cetirizine (Zyrtec).
Treatment of the Common Cold
*Involves combined use of antihistamines, nasal decongestants, antitussives, & 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 “empiric therapy,” treating the most likely cause.
*Antivirals and antibiotics may be used, but a definite viral or bacterial cause may not be easily identified.
