Allergies Flashcards
What is released by mast cells upon contact with allergens?
Histamines, Cytokines, prostaglandines and more
The sequence of allergens and allergic reaction:
Allergen enters mucous membrane (nose) -> taken up by APC to T-cells -> T cells stimulate B-cells to produce IgE antibodies -> IgE antibodies sit on the surface of mast cells -> mast cells have granules containing mediators like histamine and prostaglandins
-> allergens bind to the IgE antibodies on the mast cells causing the release of the mediators -> the mediators like histamine cause vasodilation and increased permeability of the blood vessels -> nasal stuffiness, sneezing, and mucus discharge
How do Anit-Histamines work?
Blocking of receptors of histamines receptors on blood vessels -> preventing vasodilation and material from moving into the tissue
What type of therapies against allergies?
-Antihistamines, Mast stabilizers, Vasoconstrictor
Which three allergic diseases have a genetic component involved?
Allergic Rhinitis, Allergic dermatitis, Asthma
-If patients have one there is a possibility that they have more or all three
Which three allergic diseases have a genetic component involved?
Allergic Rhinitis, Allergic dermatitis, Asthma
-If patients have one there is a possibility that they have more or all three
-Treating allergic rhinitis might help patients with their asthma
What are the risk factors for allergic Rhinitis?
-Family history
-elevated Ige
-Smoking
-exposure to allergens:
seasonal -> pollen
perennial -> dust mites, pet hair
Which drugs induce Rhinitis?
-ACE-inhibitor
-Phosphodiesterase-5 selective inhibitors
-Phentolamine
-Alpha-receptor antagonists used for blood pressure, prostate, cause vasodilation
-NSAIDs including aspirin
-Oral contraceptives
15-20% of patients treated will be associated with Rhinitis caused by these drugs
When is Rhinits considered nonallergic?
When IgE is not the causing factor
-Hormonal, structural (deviated nose-septum), drug-induced, trauma
What are some complications:
Polyps, sleep apnea, decreased sense of smell
What are the treatment options?
Nondrug (avoid allergens, nasal wetting agents)
-Intranasal corticosteoroids
-Antihistamines: 1st and 2nd than intranasal
-Mast cell stabilizer
-Dietary supplements
Nasal wetting agents:
-removes nasal dryness and crusting
-well tolerated, may cause stinging and burning bc of the formulation (not isotonic)
-the device has to be cleaned and the wash mixture discarded after nasal rinsing -> may cause infections
-use boiled or distilled water
How do Corticosteroids work?
They limit T-cell and B-cell operation
Intranasal Corticosteorids: Flonase
-API: Fluticasone propionate
-for runny nose, sneezing,
-side effects: Epistaxis (nose bleeding) caused by the administration and thinning of mucus layer due to steoroids
Intranasal Corticosteorids: Flonase
Alternatives: Nasacort (API: Triamcinolone acetonide),
Rhinocort (API: Budesonide)
-API: Fluticasone propionate
-for runny nose, sneezing,
-side effects: Epistaxis (nose bleeding) caused by the administration and thinning of mucus layer due to steroids
Do INCS decrease terminal growth due to steroids?
-There is no evidence that nasal sprays (asthma meds) decrease terminal growth but they may decrease growth velocity in high concentration
First Gen Sedating Antihistamines: Benadryl + Chlor-Trimeton
API: Diphenhydramine hydrochloride
-Indication: Allergy symptoms and sleep aid
-Side effects: Drowsiness, dizziness
-Drug interaction: CNS depressants, Anticholinergics (blocks ACh, for parasympathetic)
-for 6-12y and adults NOT elderly
API: Chlorpheniramine maleate
-Indication, the side effect is the same
-for 6-12y and adults NOT elderly (listed in beers criteria)
When should First Gen Sedation Antihistamine NOT be used?
-Patients with
-Breathing problems, problem urinating due to enlarged prostate, Glaucoma, Dementia -> often in older patients
Second Gen Sedating Antihistamines: Claritin and Allegra
(Nonsedating bc they don’t cross the blood-brain barrier easily compared to the first generation)
Claritin (Alavert)
-API: Loratadine
-Indication: Allergy symptoms
-Side effects: Headache, Xerostomia (dry mouth)
-Drug interaction: Amiodarone (QT prolongation, irregular heart rhythm)
-Age: 8 and above, CAUTION with elder people
Allegra
-API: Fexofenadine hydrochloride
Drug interaction: problems with absorption when taken with magnesium antacids or fruit juice
-Age: 8 and above, CAUTION with elder people
Other examples:
Zyrtec / Xyzal -> API: Cetirizine HCl / levocetirizine dihydroCl
Mast cell stabilizer: NasalCrom
-API: Cromolyn sodium
-are very effective, it is a preventive product
not for treatment
-have to be taken 2 weeks in advance, bs, when the histamines are released stabilizing the mast cells, won’t help anymore
-its efficacy and onset are lower than intranasal steroids
Mast cell stabilizer profile
-For allergic symptoms
-Side effects: nasal irritation
-Age: 2y and older
-Plower absorption in pregnant women
When are intranasal CS and when are Oral Antihistamines preferred?
In intermitted allergies: Oral AH 2G is the first line bc they work pretty quickly (60min), is reasonable and the patient doesn’t need it all the time
2. Intranasal AH (faster onset)
3. OAH 2G with vasoconstrictor
4. Intranasal Corticosteroid
For persistent allergies, Intranasal CS is the first line followed by Antihistamines
How do Corticosteroids work?
They limit T-cell and B-cell operation
