PAC3421 Study Guide - Final Guide: Allergic Rhinitis, Nasal Spray, Oxymetazoline
21 Jun 2018
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Treatment for ALLERGIC and NON-ALLERGIC Rhinitis:
1. Corticosteroids
Mometasone and oral prednisolone are S4, don’t ever choose these options on MCQ!!!
2. Decongestants
oPseudoephedrine
Pseudoephedrine enters noradrenergic nerve terminals. It gets taken up into the synaptic
vesicles in exchange for noradrenaline. Noradrenaline then escapes into the cytosol in
which some of those are degraded by MAO. The remaining noradrenaline escapes via
uptake1 transpoter (i.e. NOT exocytosis) into the synaptic cleft in exchange for
pseudoephedrine to act on postsynaptic receptors
oPhenylephrine
Alpha1 agonist
oOxymetazoline
Alpha1 agonist and alpha2 partial agonist
oXylometazoline
Alpha2 agonist
Better side effect profile
Rank the above decongestants on their propensity to affect one’s blood pressure from worst to best based on their
mechanism of action and delivery.
a) Pseudoephedrine because it causes release of NA
b) Phenylephrine (acts to a certain degree but doesn’t increase BP as much as pseudo)
c) Oxymetazoline (spray form, no go into systemic circulation)
d) Xylometazoline (spray form, alpha2 receptor not involved in BP)
3. Antihistamine
oCan be in oral or nasal form
oCan be sedating or non-sedating
oMechanism: Reversible competitive antagonism of histamine at H1 receptor to decrease vascular
permeability and increase smooth muscle relaxation
4. Leukotriene receptor antagonists
a. Montelukast
5. Mast Cell Stabilisers
a. Azelastine (a nasal antihistamine with mast cell stabilising properties)
find more resources at oneclass.com
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Document Summary
Treatment for allergic and non-allergic rhinitis: corticosteroids. Mometasone and oral prednisolone are s4, don"t ever choose these options on mcq!: decongestants, pseudoephedrine. It gets taken up into the synaptic vesicles in exchange for noradrenaline. Noradrenaline then escapes into the cytosol in which some of those are degraded by mao. The remaining noradrenaline escapes via uptake1 transpoter (i. e. not exocytosis) into the synaptic cleft in exchange for pseudoephedrine to act on postsynaptic receptors: phenylephrine. Alpha1 agonist and alpha2 partial agonist: xylometazoline. Highly vascularised: composed of resistance (i. e. arterial sinusoids) and capacitance blood vessels (i. e. Highly vascularised: composed of resistance (i. e. arterial sinusoids) and capacitance blood vessels (i. e. venous sinusoids) The nasal venous sinusoids are richly innervated by sympathetic nerves in which noradrenaline is released upon stimulation of the nerves. Released noradrenaline binds to postjunctional alpha1 & alpha2 receptors (gq receptor) found on the venous sinusoids to cause vasoconstriction. This decreases blood flow to the venous sinusoids to reduce nasal congestion.
