OTC Cough and Cold Flashcards
what do common OTC contain singly or a combination of? (4)
decongestant, cough suppressant (antitussive), expectorant and antipyretic
what do OTC cough and cold medications usually treat?
upper respiratory infections (runny nose, congestion, cough, fever)
what is the cough reflex?
reflex to clear breathing passage of irritants, microbes, fluids and mucus
what is the cough reflex a common symptom of? (4)
upper respiratory tract viral or bacterial infections, asthma, bronchial irritation, etc.
what is the cough reflex initiated by?
stimulation of sensory nerves in throat and lungs (eg. P2X3, TRPV1)
where do sensory neurons send “cough info” to?
medulla oblongata (cough center in brain stem)
what do efferent nerves (parasymp. and motor) stimulate in the cough reflex?
diaphragm, intercostal muscles and lungs to initiate “noisy expiration”
what are drugs that inhibit cough reflex called?
antitussives
how do most OTC antitussives work?
inhibit neurons in medulla oblongata
how effective are antitussives at reducing cough in clinical trials?
only moderately effective (not much better than placebo)
what is codeine?
mu opioid receptor agonist
where are mu opioid receptors found?
medulla oblongata (cough center) and peripheral nerves in respiratory tract
what are mu opioid receptors?
inhibitory GPCRs
how does activation of opioid receptors affect neuronal activity? (3)
inhibit of Ca channels, activate of K channels, and inhibit of adenylyl cyclase ie. neuronal inactivation and decr NT release
what are the effects of codeine?
arrests cough response (efferent) and decr respiration
what are 2 serious side effect of codeine?
addiction, overdose (death)
what was low dose codeine mixed with?
Tylenol 3s
what is dextromethorphan?
centrally active NMDA receptor antagonist
how are dextromethorphan and codeine similar and different?
sim: inhibit neurons in medulla oblongata
diff: dex-antagonist, cod-agonist
what is diphenhydramine?
antihistamine (H1 inverse agonist~antagonist)
what H1 receptors?
Gq coupled receptors
where are H1 receptors?
respiratory smooth muscles
what do H1 receptors stimulate?
sensory nerves producing cough
what does diphenhydramine binding to H1 receptors cause?
inhibits histamine action and receptor action
what does histamine binding to H1 receptors cause?
in resp. tract - coughing
what allows diphenhydramine to inhibit cough reflex in medulla oblongata?
can cross BBB (blood brain barrier)
what do decongestants do?
decr nasal congestion, edema (swelling) of nasal passage, decr tissue hyperemia, etc.
what is pseudoephedrine?
agonist for a and B adrenergic receptors (sympathomimetic drug-mimics noradrenaline)
what does activation of a adrenergic receptors by pseudoephedrine cause?
vasoconstriction of blood vessels in mucosa of resp. tract
what does activation of B adrenergic receptors by pseudoephedrine cause?
smooth muscle relaxation and vasodilation (bronchi)
what is pseudoephedrine structurally similar to?
amphetamine (stimulant)
what is phenylephrine?
specific a adrenergic receptor agonist
what does phenylephrine binding to a adrenergic receptors cause?
vasoconstriction in nasal mucosa (no bronchial relaxation or HR incr) - less effective
what are expectorants?
oral drugs that incr mucus clearance
what expectorant was not removed from the market in the 90s by the FDA/Health Canada?
Guaifenesin (Mucinex)
where was guaifenesin discovered by indigenous communities?
bark of Guaiac tree
how does guaifenesin work?
incr expulsion of bronchial secretion by dec adhesiveness and surface tension of mucus
what is theorized to be the mechanism of action of guaifenesin? (not actually known)
irritate gastric vagal receptors that recruit efferent parasymp. reflexes causing glandular exocytosis of less viscous mixture
Why is codeine not recommended for individuals under 18 y/o?
Children are at higher risk for on-target effects leading to respiratory depression
