Chronic Rhinitis, Cough, And Cold Medications

Question 1

Dextromethorphan

Answer 1

MOA: Crosses the blood-brain-barrier and activates sigma opioid receptors on the cough center in the central nervous system (medulla), thereby suppressing the cough reflex. Does not affect ciliary activity (in the bronchial tree)
INDICATIONS: for short-term relief of cough
INTERACTIONS: Avoid co-use with MAOIs and in SSRI/SNRIs as it can cause serotonin syndrome
ADVERSE DRUG EFFECTS:
* Mild and infrequent dizziness and drowsiness
* At very high doses (when used recreationally) can cause hallucinogenic state
* Serotonergic effects
CONTRAINDICATIONS:
* Avoid in chronic cough
* Avoid in hepatic disease
* Avoid when operating machinery

Question 2

Codeine (Opioid)

Answer 2

MOA: Suppresses cough reflex centrally (though evidence does not necessarily support this). Dries bronchial secretions.
INDICATIONS: for short-term relief of cough, co-administered with guaifenesin
INTERACTIONS:
* Converts to morphine in liver via cytochrome P450
* Concomitant use of opiates leads to sedation and respiratory depression
Adverse Drug Effects:
* Tolerance
* respiratory depression,
* sedation
* N/V
* potential for abuse
*pruritis
CONTRAINDICATIONS:
* Ileus (dysmotility of colon or intestines)
* respiratory depression
* head injury
* seizures
* hepatic failure

Question 3

Benzonatate

Answer 3

MOA: Anesthetizes the stretch receptors of vagal afferent fibers in the lungs, reducing the urge to cough after deep inhalation; peripherally-acting
INTERACTIONS:
* Can be additive to other local anesthetics
INDICATIONS: mostly for relief of chronic cough, but sometimes used for acute cough (with variable success)
Adverse Drug Effects:
* Well tolerated
* GI upset
* local anesthesia from chewing
* Overdose
* cardiac arrhythmia
* seizure
* bronchospasm
CONTRAINDICATIONS : Avoid in allergy to ester anesthetics

Question 4

Guaifenesin: Expectorant

Answer 4

MOA: Loosens secretions to allow for more productive cough, Increases volume and reduces viscosity of phlegm in trachea/bronchi, Cilia can then more easily propel/mobilize secretions upwards
INDICATIONS: treatment of acute cough. Often combined with dextromethorphan (DM) or pseudoephedrine (‘D’) but also available as monotherapy (syrups, pill form)
CONTRAINDICATIONS:
* Should not be used for chronic cough
* Avoid in pediatrics; can lead to seizures in this population
Adverse Drug Effects:
* Rare at recommended doses
* Excessive use can result in nephrolithiasis

Question 5

Antihistamines (first generation)

Answer 5

Diphenhydramine (Claritin), hydroxyzine (Vistaril or Atarax)
MOA: Blocks the effects of histamine.
INDICATIONS: allergy symptoms, generally better used for acute allergy. Act quick, q6h, sedating; hydroxyzine can be used as an anxiolytic agent
CONTRAINDICATIONS: Avoid in elderly; may cause delirium, dizziness, urinary retention

Question 6

Antihistamines (second generation)

Answer 6

Cetirizine (Zyrtec), loratadine (Claritin) & fexofenadine (Allegra)
MOA: Blocks the effects of histamine.
INDICATIONS: allergy symptoms, 24 hour non drowsy formulation. Cetirizine crosses BBB a little, little drowsiness but better for itching, hives
CONTRAINDICATIONS: better choice for elderly patients except for cetirizine.

Question 7

Pseudoephedrine

Answer 7

Decongestant
MOA: Sympathomimetic, α- and β2-adrenergic receptor agonist. Direct stimulation of alpha-adrenergic receptors of respiratory mucosa causes vasoconstriction and of beta-adrenergic receptors causes bronchial relaxation. Therefore reduces tissue hyperemia and edema.
Indications:
* acute nasal congestion
* sinusitis
* otitis media
Adverse drug effects:
* Increases heart rate and contractility
* Is a chemical precursor to the manufacture of methamphetamine (behind the counter for this reason)
Contraindications:
* heart disease
* severe hypertension
* uncontrolled diabetes

Question 8

Phenylephrine

Answer 8

MOA: Binds primarily to α1 receptors, causing vasoconstriction
Indications: Used as a nasal decongestant, Less effective than pseudoephedrine for treatment of rhinitis symptoms,
Available in oral or intranasal preparations
Adverse Drug Effects:
* Increases systolic and diastolic pressure
* Induces reflex bradycardia
Drug interactions:
* ACE inhibitors, CCBs can increase clearance, making less effective
* Interaction with MAOIs, tricyclic antidepressants can increase concentration

Question 9

Oxymetazoline (Afrin)

Answer 9

Topical Decongestant.
Dosing: Long-acting form (~12 hours per spray), Dosed twice daily for maximum of 3 days
Indications: acute rhinitis (from the common cold, e.g.)
Adverse Drug Effects: Longer duration of use can lead to rebound congestion

Question 10

Fluticasone

Answer 10

Mometasone, Budesonide also available in intranasal
MOA: glucocorticoid receptor agonist which causes vasoconstriction and inhibitory effects of cells and mediators of inflammation
INDICATIONS: treatment and prevention of allergic rhinitis; treatment of chronic nasal polyps. Not indicated for treatment of acute upper respiratory infections. Nasally inhaled.
Adverse Drug Effects:
* epistaxis
* pharyngitis; systemic absorption of steroid is possible

Question 11

Inhaled Antihistamines

Answer 11

Azelastine and Olopatadine
Indications: allergic rhinitis in adults and children > 12 yo
Adverse Drug Effects:
* Nosebleeds
* headaches
* somnolence (drowsiness)
* poor taste