PHARM: Cough Suppressants, Decongestants, Mucolytics Flashcards
How many phases are there of a cough?
3: Inspiratory phase, compressive phase, expulsive phase
Describe the 3 phases of a cough.
1) Inspiratory effort
2) Forced expiratory effort against a closed glottis
3) Opening of the glottis and rapid expiratory airflow
Where are cough receptors located?
airway bifurcations in the larynx and distal esophagus
Though what nerves to cough afferents link to the cough center/cerebral cortex?
vagus and superior laryngeal nerves
True or false: afferent pathways control the muscle response that leads to cough.
FALSE: efferent pathways do
What type of cough lasts less than three weeks?
acute
What type of cough lasts three to eight weeks?
subacute
What type of cough lasts greater than 8 weeks?
chronic
Malodorous secretions with cough indicate what type of infection?
anaerobic
What is an antitussive?
drug to prevent (nonproductive) cough
Antitussives are divided into what two groups?
Systemic
Topical
List some systemic antitussives.
Dextromethorphan
Diphenhydramine
Codeine
List some topical antitussives.
Camphor
Menthol
What is an expectorant?
drug to help productive coughs (with thick secretions) bring up mucus
What is an example of an expectorant?
Guaifenesin
What is the MOA of dextromethorphan?
Supresses the cough reflex by a direct action on the cough center int he medulla of the brain
How is dextromethorphan metabolized?
CYP2D6 into its active metabolite (dextrorphan)
What are the side effects of dextromethorphan?
Dizziness, drowsiness, N/V, diarrhea, excitability, trouble sleeping; HALLUCINOGENIC (pseudobulbar effect)
Dextromethorphan is contraindicated in what individuals?
those on MAOI antidepressants**
those who have advanced respiratory insufficiency, hepatic disease, or hypersensitivity
What is diphenhydramine?
Benadryl
What type of drug is diphenhydramine?
Antihistamine-H1 receptor antagonist
What is the MOA of diphenhydramine?
Supresses cough reflex by direct effect on cough center and due to its anticholinergic effects
What are some side effects of diphenhydramine?
Drowsiness Respiratory depression blurred vision Urinary retention constipation
In what patients is diphenhydramine contraindicated?
Prostate hypertrophy urinary obstruction asthma COPD peptic ulcers MAOI takers
What type of drug is codeine?
opioid analgesic and antitussive (related to morphine but has lower affinity for mu receptors)
How does codeine depress the cough reflex?
direct action on cough center in CNS
What are some side effects of codeine?
constipation sedation histamine release vasodilation orthostatic hypotension dizziness
In what people is codeine contraindicated?
hypersensitivity Pregnant women Prostatic hypertrophy patients Individuals on sedatives People with asthma, OCPD, or ARD
Topical agents can come in what forms?
Ointments (to rub on throat)
Lozenges
Inhalation (breathe in medicated vapors)
What does guaifenesin do?
loosens and thins lower respiratory tract secretions by increasing the volume and reducing the viscosity of secretions
(used in goat sedation)
What are side effects of guaifenesin?
Dizziness Dry mough rash Diarrhea Uric acid nephrolithiasis* (in large doses)
What are nasal decongestants?
vasoconstrictive drugs that reduce nasal congestion without affecting release of histamine/other mediators of allergic reaction (so commonly formulated with antihistamines)
What is the MOA of nasal decongestants?
alpha-adrenergic agonist that stimulates blood vessels to constrict to reduce blood supply to nose and sinusoid vessels (decreasing mucosal edema
List some oral (systemic) decongestants.
Pseudoephedrine (Sudafed)
Phenylephrine (Sudafed PE)
What is the difference between pseudoepherine and phenylephrine?
Pseudoephedrine releases NE from adrenergic nerves while phenylephrine directly stimulates adrenergic receptors on post-synaptic sites
Which has a greater bioavailability: pseudoepherine and phenylephrine??
pseudoephedrine (only minorly metabolized–around 100% bioavailability compared to 38%)
List some side effects of systemic decongestants.
CV stimulation
CNS stimulation
more likely experienced by children and elderly
Rebound congestion (ischemic as result of local vasoconstriciton of drug or local irritation of drug)
Why is pseudoephedrine a behind the counter OTC?
Meth Check monitors it
List the types of topical nasal decongestants.
Sprays
Drops
Inhalers
What is an example of a decongestant spray? When is this preferred?
oxymetazoline (alpha 1 agonist preferred for pregnancy)
Why should you not use oxymetazoline over 3-5 days?
can cause rhinitis medicamentosa
List medications used in decongestant inhalers.
Levamfetamine
Propylhexadrine (acts on alpha receptors and indirectly increases NE release)
What are mucolytics?
drugs that promote the breakdown of mucus in diseases like CF, COPD, Bronchiectasis, and Respiratory Infections
What is the structure of mucus?
Large macromolecule made up of polypeptide backbone with carbohydrate side chains (held together by dipeptide links (connect AA) and disulfide/hydrogen bonds (connect adjacent macromolecules))
List ways to facilitate the clearance of mucus.
- Provide adequate hydration
- Remove causative factors
- Optimize tracheobronchial clearance
- Reduce inflammation
What is a bland aerosol?
a “wetting agent” that dilutes mucus
List examples of bland aerosols.
- Sterile and distilled water
- Normal saline
- Hypertonic saline (increase mucus production)
- Hypotonic saline
List examples of expectorants that act as mucolytics.
Iodides
Guiafenesin (stimulates bronchial gland secretion at high doses)
Bromohexin (increases production of serous mucus in respiratory tract and decreases the viscosity of phlegm)
List a commonly used mucolytic.
N-Acetly Cysteine
How does N-acetyl cysteine work?
breaks the bonds of mucus by substituting a sulfhydryl radical -HS
How is N-acetyl administered?
aerosol or directly into ET tube
What is a side effect of mucolytics?
Bronchospasm (watch out with asthma)
Increased mucus production (bad for people without ability to cough or who are intubated)
BAD ODOR
Easily contaminated
Can you mix a mucolytic and an antibiotic in the same nebulizer?
NO- incompatible
How does sodium bicarbonate act like a mucolytic?
increases the pH of mucus by weakening the carbohydrate side chain–> which weakens the polysaccharide chains
How can you administer sodium bicarbonate?
injection into trachea or aerosolized (but irritating)
What is dornase alfa?
clone of the natural human pancreatic DNase enzyme which digests extracellular DNA that reduces the viscosity of secretions during infection
Who uses dornase alfa?
cystic fibrosis patients or patients with chronic bronchitis/bronchiectasis
*has NO effect on non-infected sputum
What are side effects of dornase alfa?
voice alteration
conjunctivitis*
chest pain
Who cannot take dornase alfa?
patients hypersensitive to Chinese Hamster Ovary cell products
What is amiloride?
diuretic that can be given by aerosol to block sodium channels in the epithelium (preventing the dehydration of mucus)–sodium is not allowed to go in to epithelium with water like in CF
What is another CF drug that enhances mucosal hydration by activating Cl-secretion and inhibiting Na+ transport across the epithelium?
Denufosol Tetrasodium
How does denufosol tetrasodium work?
activates P2Y2 receptors
How do laryngeal and pulmonary receptors (ex. C-fibers) relay input to brainstem medually central cough generator?
via intermediate relay neurons in the nucleus tractus solitarius
Which receptors in the larynx respond to cold (menthol)?
TRPV-8
What receptors in the larynx respond to stretch?
slow adapting fibers
What receptors in the larynx respond to pH changes and irritants?
C-fibers
What types of receptors are the “cough receptors”?
G-protein coupled ion channels
What type of innervation do blood vessels NOT get?
parasympathetic
What type of innervation do mucous glands NOT get?
sympathetic
What type of molecules are released from synapses at the nasal epithelium to vasodilate and increase vascular permeability leading to congestion?
Neuropeptides (ex. neurokinin A, CGRP)
Which decongestant is a selective alpha-1 agonist?
phenylephrine
How does phenylephrine cause reflex bradycardia?
Vasoconstriction leads to baroreflex that increases Ach and decreases NE release–> slows heart
Why does rebound congestion occur with decongestants like PE?
if you use for over 7 days, receptors get desensitized and you get infection (if no blood flow to area, no way to fight infectious particles off!)
