Cough Suppressants, Decongestants, Mucolytics Flashcards
What are the phases of coughing?
inspiratory phase -
compressive phase - forced epiration against closed glottis
expulsive phase - open glottis and rapid expiratory airflow
Where are the cough receptors found? What nerves do they send signals to cough center through?
at airway bifurcations and at the distal esophagus. Send cough afferents through the vagus and superior laryngeal nerves
Where is cough center located?
medulla
What length of time defines chronic cough? acute?
chronic is longer than 8 weeks. Acute is shorter than 3. Anything in between is subacute
What class of drugs are the DOC for nonproductive coughs?
antitussives
What is the DOC for productive coughs with thick secretions?
guaifenesin (expectorant)
What is the mechanism of Dextromethorphan? Side effects? Notable facts?
suppress cough reflex by direct action through cough center in the medulla of the brain. NMDA receptor. Nonopiod with potency equal to codeine. Dizziness, drowsiness, trouble sleeping. Contraindicated in those taking MAOI’s (monoamine oxidase inhibitors). Large doses produce hallucinogenic effect
What is the mechanism of Diphenhydramine? Side effects? Notable facts?
antihistamine -H1 receptor antagonist. suppresses cough through anticholinergic effects. Can cause drwsiness, respiratory depression, constipation, blurred vision. Can NOT give to patients with prostate hypertrophy, asthma, COPD, or those on MAOI’s.
What is the mechanism of
codeine? Side effects? Notable facts?
opioid anagesic and antitussive. Acts on Mu receptors to depress cough reflex through CNS. 10% is metabolized to morphine. Can cause constipation, sedation, histamine release, vasodilaiton, orthostatic hypotension. Contraindicated in labor, prostatic hypertrophy, sthma and COPD.
What is the mechanism of guaifenesin? Side effects? Notable facts?
Only FDA approved expectorant. Not used for chronic coughs. Increases volume of respiratory tract secretions to reduce viscosity. Can cause dizziness, dry mouth, drowsiness, and uric acid nephrolithiasis.
What are nasal decongestants? What effect do they have on release of histamine?
vasoconstrictive drugs. Usually alpha-agonists. They have no effect on the release of histamine or any other allergic mediators. Include oral pseudoephedrine and phenylephrine, as well as nasal oxymetazoline and inhaled levamfetamine and benzadrex.
What is the mechanism of pseudoephedrine? Side effects? Notable facts?
acts by rleasing norepinephrine from adrenergic nerves. Barely metabolized. 88% excreted unchanged. Very bioavailable. Can cause CV stimulation and rebound congestion.
What is the mechanism of PE (phenylephrine)? Side effects? Notable facts?
acts by directly stimulateing adrenergic receptors on postsynaptic sites. It is rapidly metabolized by MOA and COMT in GI mucosa and liver. Can cause CV stimulation and rebound congestion.
What is the mechanism of Oxymetazoline? Side effects? Notable facts?
nasal spray decongestant. Can only use for 3 days before it can cause rhinitis medicamentosa. Is fast, cheap and easy.
What is the mechanism of N-acetyl cysteine? Side effects? Notable facts?
mucolytic. breaks the bonds by substituting a sulfhydryl radical -HS. Also can be given orally to reduce liver injry with acetoaminophen OD. Can cause bronchospasm. Increases mucus production. Can NOT mix with antibiotics. Smells like rotten eggs.
