Cough Suppressants, Decongestants, Mucolytics Flashcards

1
Q

Describe the 3 phase expulsive motor act of cough

A
  1. Inspiratory effort (Inspiratory Phase)
  2. Forced expiratory effort against a closed glottis (Compressive Phase)
  3. Opening of the glottis and rapid expiratory airflow (Expulsive Phase)
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2
Q

Pathophysiology of Enhanced Cough Reflex

A

Laryngeal and pulmonary receptors, such as rapidly adapting receptors, C-fibers, and slowly adapting fibers, and cough receptors provide input to the brainstem medullary central cough generator through the intermediary relay neurons in the **nucleus tractus solitarius. **

Central cough generator then establishes and coordinates the output to muscles that cuase cough.

Cerebral cortex can control the motor output of cough volitionally, or influence the urge-to-cough sensation.

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3
Q

Define:

  • Acute Cough
  • Subacute Cough
  • Chronic Cough
A
  • Acute Cough: < 3 weeks
  • Subacute Cough: 3-8 weeks
  • Chronic Cough: > 8 weeks
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4
Q

Describe Productive Cough

A

Wet cough with secretions

  • Clear - bronchitis
  • Purulent - Bronchial infection
  • Yellow - Inflammatory disorders
  • Malodorous - Anaerobic Infection
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5
Q

Describe Non-Productive Cough

A

Dry hacking cough that does not remove sputum from the respiratory tract

  • Viral illness
  • Bronchospasm
  • Allergies and Asthma
  • Airway Obstruction
  • GERD
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6
Q

Describe the pharmacologic treatment options for cough

A

Antitussives: OTC for nonproductive coughs

  • Systemic Agents: Dextromethorphan, Diphenhydramine, Codeine
  • Topical Agents: Camphor, Menthol (act on TRP channels)

Expectorants: OTC for productive coughs with thick secretions

  • Guaifenesin
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7
Q

Dextromethorphan (DXM, DM, dextro isomer of levomethorphan) MOA

A

Supresses the cough reflec by a direct action on the cough center in teh medulla of the brain

  • Active ingrediant in many cold and cough medicines (e.g. Robitussin, NyQuil, etc)
  • Metabolized by CYP2D9 into active metabolite dextrorphan
  • Wide margin of safety
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8
Q

Dextromethorphan Side Effects and Contraindications

A

Side Effects: dizziness, drowsiness, nausea, upset stomach, vomiting, diarrhea, irritability, excitability, light headedness, trouble sleeping.

Contraindications: monoamine oxidase inhibitor ntidepressants, advanced respiratory insufficency or hepatic disease

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9
Q

Diphenhydramine (Benadryl) MOA

A

Antihistamine-H1 receptor antagonist that suppresses the cough reflex by a direct effect on the cough center.

  • Antitussive effects due to its anticholinergic effects
  • Second line agent - indicated for nonproductive cough caused by irritation
  • Other uses: common cold, allergic rhinitis, chronic urticaria, motion sickness, parkinsonism, insomnia
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10
Q

Diphenhydramine (Benadryl) Side Effects and Contraindications

A

Side Effects: drowsiness, respiratory depression, blurred vision, dry mouth, urinary retention, constipation

Contraindications: prostate hypertrophy, urinary obstruction, asthma, COPD, peptic ulcer, MAOI’s

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11
Q

Codeine (3-methylmorphine) MOA, Side Effects, Contraindications

A

MOA: opioid analgesic and antitussive related to morphine that acts on mu receptors but has lower affinity than morphine. It depresses the cough reflex by a direct action on the cough center in CNS.

Side Effects: constipation, sedation, histamine release, vasodilation, orthostatic hypotension, dizziness

Contraindications: hypersensitivity, labor of premature birth, pregnancy category C, prostatic hypertrophy, individuals on sedatives, in patients with acute respiratory depression, asthma or COPD

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12
Q

Guaifenesin (Mucinex, Albatussin EX, Alfren Jr, Alorant, Amibid) MOA, Side Effects, Contraindications

A

MOA: loosens and thins respiratory tract secretions by increasing the volume and reducing the viscosity of secretions

  • symptomatic relief of productive coughs
  • not used for chronic coughs
  • only FDA approved expectorant

Side Effects: dizziness, dry mouth, rash, diarrhea, drowsiness, n/v, stomach pain, diarrhea, uric acid nephrolithiasis

Contrindication: hypersensitivity

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13
Q

What are nasal decongestants?

A
  • vasoconstrictive drugs that reduce nasal congestion
  • do not affect release of histamine or any other mediators involved in the allergic reaction
  • commonly formulated with antihistamines
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14
Q

MOA of nasal decongestants

A
  • alpha-adrenergic agonists (sympathomimetic)
  • stimulation of alpha-adrenergic receptors constricts blood vessels through the body
    • reduces the supply of blood to the nose
    • decreases the amount of blood in the sinusoid vessels
    • decreaes mucosal edema
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15
Q

What are the oral (system) decongestants

A

Pseudoephedrine: releases NE from adrenergic nerves

  • metabolized to only a minor extent, by N-demethylation to norpseudoephedrine. Up to 88% of dose is excreted unchanged in 36h urine
  • better bioavailability than PE, but both have short half lives

Phenylephrine (PE): stimulates alpha-adrenergic receptors on postsynaptic sites

  • rapidly metabolized by MOA and COMT in the GI mucosa, liver and other tissues
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16
Q

What are the side effects of systemic decongestants?

A
  • CV stimulation: increase BP, tachycardia, palpitation, arrhythmias (note that ACh will cause reflex BRADYCARDIA via baroreceptor reflex)
  • CNS stimulation: restlessness, insomnia, anxiety, tremors, fear, hallucinations
  • Children and elderly are more likely to experience
  • Cause of rebound congestion: ischemic as a result of local vasoconstriction or irritation of the drug
17
Q

What are the precautions and contraindications of systemic decongestants?

A
  • In children and elderly
  • Hyperthyroidism
  • Bradycardia (PE)
  • Partial heart block
  • Hypersensitivity
  • Uncontrolled HTN
  • Ventricular tachycardia
18
Q

What are the topical nasal decongestants?

A

Sprays, drops, inhalers

19
Q

What are the two sprays approved for nasal decongestion?

A

Oxymethazoline: do not use more than 3-5 days becuase it can cause rhinitis medicamentosa; preferred topical agent in pregnancy

PE

20
Q

What are the advantages and disadvantages of sprays?

A

Advantages:

  • fast onset of action
  • inexpensive
  • simple to use
  • cover a large surface area

Disadvantages:

  • imprecise dosage administration
  • tip tends to get blocked
21
Q

What are the advantages and disadvantages of drops?

A

Advantages:

  • for small children

Disadvantages:

  • awkward to use
  • cover a limited surface area
  • pass easily into larynx
  • easily contamined if dropper touches nose
22
Q

What are the two types of inhalers?

A

Vicks Vapor (Levamfetamine)

  • Does not cause nasal rebound for 7 days
  • Labeling advises to see MD if Sx persist for more than 3 days

Benzadrex (Propylhexadrine)

  • Abused
23
Q

What are mucolytics and when are they used?

A

Promote the breakdown of mucus and are used in diseases in which there is increased mucus production (e.g. CF, COPD, Bronchiectasis, TB)

24
Q

Describe the structure and fucntion of mucus

A

Glycoprotein with chemical bonds that “hold” mucus together

  • Intramolecular (dipeptide links) connect AA
  • Intermolecular (disulfide and H-bonds) connect adjacent macromolecules
25
Q

How can you facilitate mucus clearence?

A
  • Provide adequate hydration by increasing fluid intake orally or IV
  • Remove causative factors (smoking, pollutants, allergens)
  • Optimize tracheobronchial clearence
  • Reduce inflammation
26
Q

N-Acetyl cysteine, Acetadote, Erdosteine, Carbocysteine MOA and Side Effects

A

MOA: breaks the bonds by substituting a sulfhydryl radical

Adminstration

  • given by aerosal or direct instillation into ET tube
  • given orally (N-acetylcysteine) to reduce liver injury with acetominophen overdose.

Side Effects

  • Bronchospasm: ma be a problem during acute asthma attack
  • Increase mucus production
  • Do not mix with ABX in same nebulizer
  • N/V
  • Diagreeable odor d/t hydrogen sulfide
27
Q

Sodium Bicarbonate

A
  • Increase pH of mucus by weakening carbohydrate side chains
  • Can be injected directly into the trachea or aerosolized
  • Can be irritating
28
Q

Dornase Alfa (Pulmozyme)

A

MOA: Clone of the natural human pancreate DNase enzyme which digests extracellular DNA.

  • Recombinant human deoxyribonuclease (rhDNase)
  • Reduce viscosity of secretions during an infection by breaking down extracellular DNA

Indications: CF, chronic bronchitis or bronchiectasis. Has no effect on non-infected sputum

Side Effects: voice alteration, pharyngitis/laryngitis, rash, chest pain, conjunctivitis

Contraindications: in patients hypersensitive to Chinese Hamster Ovary Cell products

29
Q

Amiloride (Midamor)

A

Na-channel blocker diuretic that can be given by aerosol for patients with CF.

  • In CF, Na+ is absorbed into the epithelium along with H20, leaving the mucus thick and dehydrated. By blocking Na absorption, dehydration of mucus is prevented.
30
Q

Denufosol Tetrasodium

A

Enhances mucosal hydration and mucus clearence by activating Cl- secretion and inhibiting epithelial Na+ transport via activation of P2Y2 receptors