Allergy Drugs Flashcards
Skin or blood allergy tests are mediated by:
IgE
Purpose of nasal irrigation and types
Nasal irrigation rinses out allergens and mucus, increases ciliary function and reduces swelling. Nasal wetting agents (saline, propylene and polyethylene glycol sprays) or nasal irrigation with warm saline (isotonic or hypertonic) may reduce symptoms.
Saline solutions are either isotonic (0.9%) or hypertonic (2-3.5%).
Mechanism of immunotherapy
turning the Th2 IgE-based response into a Th1 response and providing relief to some allergy sufferers
First line treatment for mild to moderate allergies
Oral antihistamines
Effects of antihistamines
They are effective in reducing symptoms of itching, sneezing, and rhinorrhea, but have little effect on nasal congestion.
First gen antihistamines examples
Diphenhydramine, Doxylamine, Hydroxazine, Promethazine, Meclizine
Antihistamines MOA
The H1 antihistamines resemble the side chain of histamine and permit binding to the H1 receptor as a competitive receptor antagonist. H1 antihistamines can block most of the effects of histamine on vascular smooth muscle and nerves, thus preventing or counteracting allergic reactions. Antihistamines administered orally or rapidly absorbed and widely distributed to tissues. Many are extensively metabolized by cP450 and can interact with other drugs that are metabolized by those enzymes
Oral antihistamines warning
first-generation oral antihistamines have strong anticholinergic effects, “anticholinergic toxidrome” includes: sinus tachycardia, dry skin, dry mucous membranes, dilated pupils, constipation, ileus, urinary retention, and agitated delirium. Avoid use in the elderly particularly if already on anticholinergic meds, caution with cardiovascular disease, prostate enlargement (increases difficulty urinating), glaucoma, GI obstruction, and caution for excessive sedation.
Side effects of antihistamines
All anticholinergic: somnolence/sedation, cognitive impairment, dry mouth, blurred vision, urinary retention, constipation
Second gen preferred for pregnancy
Uses of Diphenhydramine (Benadryl®), Promethazine (Phenergan), Meclizine
Diphenhydramine (Benadryl®)- allergies if sedation is not a concern, and is ubiquitous as an over-the-counter sleeping aid, as in combination with acetaminophen, Tylenol PM sleep aid type products.
Promethazine (Phenergan®)- used widely for nausea and vomiting, with prominent sedation
Meclizine (Motion-Time®, Antivert®)- this first-generation antihistamine is indicated for motion sickness, and treatment of vertigo.
Difference in second gen antihistamines
Second-generation agents are preferred for daily treatment of allergies, since they cause less sedation and cognitive impairment due to their design which provides much less penetration through the blood-brain barrier.
Intranasal. antihistamines benefit and example
By treating the nasal mucosa directly with a topical preparation, systemic side effects are lessened (but not eliminated) while still providing control over nasal allergies.
Aselastine (Astelin ®)
First line treatment for moderate to severe rhinitis
Intranasal corticosteroids
They are the most effective medication class in controlling symptoms of chronic allergy rhinitis
MOA of intranasal corticosteroids
Intranasal corticosteroids work like any other steroids, by blocking arachidonic acid cleavage from the cell membrane and thus decreasing the synthesis of downstream inflammatory mediators.
Suffix for all intranasal corticosteroids
-side or -one
Difference in side effects between inhaled corticosteroids. and systemic
Side effects are much more likely with systemically administered corticosteroids, which used to be our only option before these drugs were developed as inhaled or sprayed topical agents.
Corticosteroids side effects
Delayed wound healing ; can cause nasal septal performation if patients do not aim away from nasal septum when giving, avoid use with recent nasal septal ulcers, nasal surgery, or nasal trauma until healing has occurred.
Inhaled corticosteroids examples
Beclomethasone (Beconase AQ®)
Budesonide (Rhinocort Aqua®)
Fluticasone (Flonase®)
Decongestant MOA
Decongestants are all alpha adrenergic agonists (sympathomimetic) and they work by causing vasoconstriction. Typically if a product has a D after it, it also contains the sympathomimetic decongestant. (i.e. Mucinex D®)
Examples of systemically active decongestants
Phenylephrine (Sudafed PE®)
Pseudoephedrine (Sudafed®)
Contraindications for systemic decongestants
caution in patients with cardiovascular disease, uncontrolled hypertension (can raise BP), hyperthyroidism (can worsen symptoms), diabetes (can increase blood glucose), glaucoma (can increase intraocular pressure), BPH (can cause urinary retention), and in the elderly. These drugs are also contraindicated in pregnancy as they cause systemic vasoconstriction–bad for the fetus to have their placental vessels vasoconstrict! Since nasal congestion (and systemic venous congestion) is universal in pregnancy, this is a clinical tip you need to know.
Side effects of systemic decongestants
Side Effects: all sympathomimetic: cardiovascular stimulation, CNS stimulation (anxiety, tremors, insomnia, nervousness, restlessness), dizziness, headache, anorexia.
Important. usage directions for intranasal decongestants
important to limit used to less than three days to prevent rebound congestion or “rhinitis medicamentosa” with discontinued use. This problem leaves the patient dependent on these agents to have a normal, non-swollen nasal mucosa if used longer than three days, an patients should be warned about this.
Use of expectorants (mucolytics)
These products are used to decrease mucus secretion viscosity (thin out mucus), to help with clearing mucous secretions out of the airway.
Example of expectorant
Guaifenesin (Mucinex®): is used to decrease mucus secretion viscosity (thin out mucus), to help with clearing mucous secretions out of the airway.
Examples of cough suppresants
Dextromethorphan (DM) and Codeine
MOA of cough suppresants
high affinity for several regions of the brain, including the medullary cough center, suppressing the cough reflex. DM also acts as a serotonin reuptake inhibitor, and an NMDA receptor blocker at high doses, which can cause a euphoric and hallucinogenic effects similar to PCP. Some states have thus banned the sale of DM to minors.
Danger of codeine dosing
Codeine’s metabolism is very unpredictable due to genetic polymorphisms and can cause respiratory suppression and death at standard doses. It should not be used for this purpose,
