PULM cough suppressants Flashcards
describe the affarent pathways that regulate cough?
SAR, RAR, and cough receptors provide input via vagus nerve to NTS relay neurons that send affarents to central cough generator
-central cough generator then coordinates the output to the muscles that cause cough
describe the efferent pathways that regulate cough?
central cough generator sends efferents via phrenic, spinal motor nerves, and recurrent laryngeal nerves to the diaphragm, intercostal muscles, laryngeal and abdominal muscles to cause cough
define acute cough
0-3 wks
define subacute cough
3-8 wks
define chronic cough
more than 8 wks
describe a productive cough
wet cough w/ secretions clear-bronchitis -purulent-bacterial infection -yellow-inflammatory disorders -malodorous-anaerobic infectino
describe a non-productive cough
dry hacking cough that does not remove sputum from the respiratory tract
- viral illness
- bronchospasm
- allergies
- asthma
- airway obstruction
what are some of the complications of cough
exhaustion urinary incontinence pain insomnia syncope stroke rib fractures
what are some of the non pharmacologic treatments of cough?
eliminating irritants hard candies like Jolly ranchers lozenges humidifiers or vaporizers hydration
MOA of dextromethorphan
suppresses the cough reflex by a direct action on the cough center in the medulla of the brain
how is dextromethorphan metabolized?
by CYP2D6 into active metabolite dextrorphan
describe the safety of dextromethorphan?
wide margin of safety, huge doses can produce dissociative hallucinogenic effect)
-non opiod (equal potency as codeine)
what are some of the adverse effects of dextromethorphan?
dizziness drowsiness nausea upset stomach vomiting diarrhea irritability
what are the need to know contraindications for dextromethorphan?
don’t take w/ MAO inhibitor, anti-depressants, advanced resp. insufficiency or hepatic disease, hypersensitivity to ingredients in product
MOA of diphenhydramine
antihistamine-H1 receptor antagonist (has many effects on NT’s in the brain)
- suppresses the cough reflex by a direct effect on the cough center
- antitussive effects due to its anticholinergic effects (muscarinic receptor blocker)
what is the cough indication for diphenhydramine?
2nd line agent, indicated for nonproductive cough caused by irritation
what are some adverse effects of diphenhydramine?
drowsiness respiratory depression blurred vision dry mouth urinary retention constipation
what are some contraindications for diphenhydramine?
prostate hypertrophy (if you block the muscarinic receptors then you have major restriction at prostate) -asthma, COPD, peptic ulcer, pts on MAO inhibitors
what is the MOA of codeine
opioid analgesic and antitussive related to morphine
- acts on mu receptors but has lower affinity than morphine
- it depresses the cough reflex by a direct action on the cough center in the CNS
what are the side effects of codeine?
constipation sedation histamine release vasodilation orthostatic hypotension dizziness
what are the contraindications for codeine?
pts w/ acute resp. depression, asthma or COPD hypersensitivity labor of premature birth Preg. Cat. C prostatic hypertrophy pts on sedatives
what are the topical cough agents?
ointments and creams: camphor, menthol, eucalyptus
Lozenges: menthol
Inhalation: camphor or menthol
How does camphor work?
they have initial stimulation hot receptors and then desensitization
MOA of guaifenesin
Expectorant-loosens and thins LRT secretion by increasing the volume and reducing the viscosity of secretions
what are the uses of guaifenesin?
symptomatic relief of ineffective productive coughs (chest congestion)
-not used for chronic coughs
what are some side-effects of guaifenesin?
dizziness dry mouth rash diarrhea drowsiness nausea vomiting uric acid nephrolithiasis (in large doses)
how do nasal decongestants work in general?
vasoconstrictive drugs that reduce nasal congestion
- doesnt affect release of histamine or other mediators of allergic rxn
- commonly formulated w/ antihistamines
how does pseudoephedrine work?
sympathomimetic adrenergic agonist that enters nerves (alpha-2, alpha-2, Beta-1) and causes them to release NE at post synaptic site–> vasoconstriction and decreased blood supply to nose, and decreased mucosal edema
How does phenylephrine work?
alpha-1 agonist that causes constriction of blood vessels and stops congestion
what enzymes metabolize Pseudoephedrine?
MOA and COMT in the GI mucosa, liver and other tissues
what is an advantage of pseudoephedrine over phenylephrine?
pseudoephedrine has better bioavailability
what are some side effects of systemic decongestants?
CV stimulation
CNS stimulation
children & elderly are more likely to experience
Cause of rebound congestion alpha1 constriction too long prevents blood to mucosa–>bacterial infection
Contraindications for decongestants?
children & elderly hyperthyroidism (increased exp. of beta-receptors in heart) bradycardia partial heart block hypersensitivity uncontrolled HTN v. tach
what is oxymetazoline
selective alpha-1 agonist as a spray
what are the advantages of decongestant sprays
- fast onset
- cheap
- simple
- cover large surface area
what are disadvantages of decongestant sprays
imprecise dosage
-tip tends to get blocked
what is advantage of decongestant drops?
for children
what are the disadvantages of decongestant drops?
awkward to use
cover limited surface area
pass easily into larynx
easily contaminated if dropper touches nose
what are some diseases that you would treat with mucolytics?
Cystic fibrosis COPD bronchiectasis resp. infections MTB
what chemical bonds hold mucus together?
intramolecular: dipeptide lin
intermolecular: disulfide and hydrogen bonds
what are nonpharmocologic ways to facilitate mucus clearance?
provide adequate hydration (increase fluid intake)
remove causative factors (smoking, pollutants)
Optimize tracheobronchial clearance
reduce inflammation
how do bland aerosols work?
dilutes mucus molecule (aka wetting agents)
may act more like irritant than wetter, mostly types of water and saline
what is the MOA of mucolytics
N-acetyl Cysteine, works by breaking bonds by substituting a sulfydryl radical-HS
what is a side effect of N-acetyl cysteine
bronchospasm
-asthma: may be a problem during acute asthma attack (use w/ bronchodilator)
what are some precautions with N-acetyl cysteine?
increased mucus production (be prep. to suction a pt who cant cough or who is intubated)
- dont mix w/ antibiotics
- N/V
- disagreeable odor
MOA of amiloride
Na+ channel blocker that can be given by aerosol for pts w/ cystic fibrosis (prevents dehydration of the mucus is prevented)
where are the cough receptors anatomically located?
at bifurcations in the larynx and at distal esophagus (link to affarents via vagus and superior laryngeal nerves to cough center)
what happens if you use oxymetazoline for more than 3-5 days?
alpha1 constriction too long, prevents blood supply to mucosa–>bacterial infection
what is the route of n-acetyl cysteine
aerosol or direct instillation into the ET tube
how does menthol work?
acts on cold receptors causing stimulation and then later desensitization
