Cough, Cold, and Allergy Flashcards
Antitussives
Reason for Use: Cough suppression
Contraindications: Concurrent MAOI (Monoamine oxidase inhibitors) use
Mechanism: Block cough centrally or peripherally
Antitussives Mechanism of Action
Central Agents: Block cough center in the brain
Examples:
IMPORTANT EXAMPLES:
- Dextromethorphan [DM]
- Codeine & Hydrocodone [opiates]
Mechanism not clear
Peripheral Agents: Anesthetize local nerve endings or act as demulcents
Examples:
IMPORTANT EXAMPLES:
- Menthol [Vicks vapo rub]
- Benzonatate [Tesselon perles]
Other examples:
Camphor, eucalyptus oil, levodropropizine
Antitussives Onset and Duration
Dextromethorphan [DM]: Onset 15-30 minutes; Duration 3-6 hours
Camphor and Menthol: Topical/inhaled
Antitussives Side Effects
Dextromethorphan [DM]: Drowsiness, nausea, dizziness
Opiates (at lower doses): Sedation, constipation
Antitussives Considerations
DM vs. Codeine: DM has fewer CNS side effects, minimal euphoria; available OTC
Caution with DM: High doses can cause dissociative effects (similar to PCP) and toxicity
«HTN, Tachycardia, Respiratory Depression»
Codeine Dosing: Lower doses for antitussive effects than for analgesia
«So less Respiratory Depression at cough doses EXCEPT pediatrics who are more sensitive to this side effect»
High doses of Opioids through IV can induce cough
Older generation Antihistamines have been used as cough meds, with unclear MOA
Expectorants
Reason for Use: Loosens mucus from the respiratory tract
Contraindications: None of major significance
Mechanism: Increase fluid in the respiratory tract
Expectorants Mechanism of Action/Examples
Mechanism: Increases respiratory fluid, and clearance of irritants, and decreases mucus viscosity
Guaifenesin unclear MOA but increases respiratory fluid through local irritant effect
Examples:
IMPORTANT EXAMPLE:
- Guaifenesin [Duratuss, Robitussin]
Other examples:
Ammonium chloride, terpin hydrate, potassium iodide, iodinated glycerol
Expectorants Side Effects
Guaifenesin: Generally well tolerated; nausea, drowsiness, vomiting at higher doses
Expectorants Considerations for recommending
Limited data for efficacy in all ages
Overdose worry
Risk of duplication of ingredients in Multi Symptom Products
Guaifenesin is widely used
Other expectorants associated with several side effects like Acidosis (in renal failure patients), nausea, and vomiting
Decongestants
Reason for Use: Nasal congestion
Contraindications: MAOIs (Monoamine oxidase inhibitors) can lead to severe hypertension. Severe HTN and coronary disease can lead to vasoconstrictive response of decongestants
Decongestants Mechanism of Action
Mechanism: Vasoconstriction of precapillary blood vessels + reduce Hydrostatic Pressure, blood flow and volume
Decongestants Examples
Direct Agonists:
IMPORTANT:
- Phenylephrine [Sudafed PE, Dimetapp]
Other Direct Agonists: Oxymetazoline, xylometazoline, naphazoline
Indirect Agonists:
IMPORTANT:
- Pseudoephedrine [Sudafed]
Other Indirect Agonists Phenylpropanolamine
Decongestants Onset and Duration
Oral Pseudoephedrine: Onset 30 minutes; Duration 4-6 hours
Topical Agents: Faster onset, fewer systemic effects
Decongestants Side Effects
CNS Stimulation: Agitation, anxiety, insomnia, because similar structure to Amphetamines
Other: Rebound nasal congestion, increased blood pressure, urinary retention, dry mouth, sweating
Topical: Local irritation
Decongestants Considerations
Rhinitis Medicamentosa: Rebound nasal congestion from chronic use, can improve over time if stop using
Pseudoephedrine Restrictions: Behind the counter, monitored by NPLEX due to potential for methamphetamine production
Vasoconstrictive options are most effective but there are other options:
Camphor, Menthol, and Eucalyptus oils
But efficacy and MOA not well studied
Antihistamines (H1 Antagonists)
Reason for Use: Allergic rhinitis, urticaria, nasal symptoms from common cold, nausea (1st generation)
Contraindications: None of major significance
Antihistamines Mechanism of Action
Mechanism: Block histamine receptors, mitigating (blocking) allergic response
Antihistamines Examples
1st Generation:
Have Anticholinergic activity so treat nausea as well.
IMPORTANT 1st GEN:
- Diphenhydramine [Benadryl]
- Chlorpheniramine [Chlortrimeton]
- Hydroxzyine [Atarax]
- Cyproheptadine [Periactin]
Others 1st Gen:
Dimenhydrinate, brompheniramine, cyclizine, meclizine, promethazine, carbinoxamine, clemastine, pyrilamine, tripelennamine, phenendamine
2nd Generation:
IMPORTANT 2nd GEN:
- Loratadine [Claritin]
- Cetirizine [Zyrtec]
- Fexofenadine [Allegra]
Other 2nd Gen:
Desloratadine [clarinex], olopatadine, acrivastine, azelastine [Astelin], levocabastine, ebastine, mizolastine
3rd Generation:
Levocetirizine [Xyzal]
Antihistamines Considerations
Sedation: Associated with some antihistamines, can cross BBB, can antagonize Serotonin (5-HT2) receptors
Use in Anaphylaxis: Not recommended due to slow onset and inability to address hypotension and bronchoconstriction
Many Antihistamines used for insomnia due to sedative effect
Doxepin, classified as a TCA (Tricyclic Antidepressant) has more potent antihistamine activity than most marketed antihistamines
Mast Cell Stabilizers
Reason for Use: Allergy conditions (e.g., asthma, rhinitis, conjunctivitis) and systemic mastocytosis (rare disorder), adjunct therapy.
Not for acute therapy, but to prevent inflammatory mediators from getting released by Mast Cells before it happens.
Contraindications: None of major significance
Mast Cell Stabilizers Mechanism of Action
Mechanism: Prevent degranulation of mast cells, suppress proinflammatory factors
(Eosinophils, neutrophils, and monocytes)
(reduce movement of Leukocytes in asthmatic airways)
Mast Cell Stabilizers Examples
Examples:
IMPORTANT:
- Cromolyn sodium [Nasal Crom]
Other examples:
Nedocromil, lodoxamide
Mast Cell Stabilizers Side Effects
Side Effects: Generally well tolerated; cough from throat irritation, nasal irritation
Mast Cell Stabilizers Considerations
No bronchodilation, so NOT useful for acute asthma attack or allergy symptoms that already started
Topical, low oral bioavailability (1%), so minimal systemic effect if swallowed by accident
Leukotriene Receptor Antagonists (LTRAs)
Indications for Use: Persistent asthma (but not 1st line, only for prevention), exercise-induced bronchospasm, allergic rhinitis
Contraindications: Acute liver disease or impaired liver function
Leukotriene Receptor Antagonists (LTRAs) Mechanism of Action
Mechanism: Block leukotrienes to reduce bronchoconstriction and inflammation
Montekulast: selective competitive antagonist of cysteinyl-leukotriene receptor and another receptor D4
Xafirlukast: selective and competitive inhibitor of D4 and E4
Leukotriene Receptor Antagonists Examples
IMPORTANT EXAMPLE:
- Montelukast [Singulair], Daily dosing
Other example:
Zafirlukast [Accolate], Twice daily dosing; monitor for liver metabolism issues, can result in 45% increase plasma level of zafirkulast if taken with other liver metabolized drugs
Intranasal Steroids
Uses: Allergic rhinitis - to reduce nasal congestion, sneezing, nasal itching, rhinorrhea
Contraindications: Hypersensitivity to medication
Intranasal Steroids Mechanism of Action
Mechanism: Inhibit inflammatory cells (mast cells, eosinophils, basophils, lymphocytes, macrophages)
Intranasal Steroids Examples
IMPORTANT EXAMPLES:
- Fluticasone [Flonase/Veramyst]
- Mometasone [Nasonex]
Other examples:
Budesonide [rhinocort]
Ciclesonide [omnaris]
Triamcinolone [nasacort]
Intranasal Steroids Side Effects
Minimal systemic absorption since Intranasal route (so much lower incidence than systemic steroids)
Slower than Antihistamines
Require continuous dosing for response
