Adrenergic Agents in Allergy Flashcards
what type of hypersensitivity?
IgE, sting, pollen, drugs
anaphylaxis, urticaria, angioedema
I: immediate
what type of hypersensitivity?
complement-dependent
IgG or IgM antibodies
II: antibody-dependent cytotoxic
what type of hypersensitivity?
exemplified by serum sickness
IgG
multisystem complement-dependent vasculitis
III: complex-mediated
what type of hypersensitivity?
contact derm from topical drugs
IV: cell-mediated
immunosuppressive drug
blocks proliferation of IgE-producing clones; inhibits IL-4 production by Th in the IgE response
prednisone
reduce release of mediators from mast cells and basophils
produce bronchodilation
adrenergic agents (isoprotenerol, epinephrine, theophylline)
histamine effect on
bp, hr
git
lungs
nerves
dec bp, inc hr
contract git
constrict lungs
stimulate nerve endings (pain, itching)
also gastric acid secretion
epinephrine (mixed a and b-adrenergic receptor agonist)
bp
git
lungs
eye
why is it the physiologic antidote to H?
INC systolic, dec diastolic bp; inc heart rate
relax intestinal sm, contract sphincters
B2-bronchodilation!!!
dec aqueous humor, inc outflow, dilate pupil
BC it activates B2-ADRENERGIC RECEPTORS -> suppress release of mediators from mast cells
why is epinephrine added to local anesthetics? (3)
dec systemic absorption
inc duration of action
dec toxicity
epinephrine CI (2)
cardiac arrhythmia
angle-closure glaucoma
epinephrine precautions (6)
elderly DM - glycogenesis CVS disease thyroid disease - amplified response rapid IV infusion - arrhythmia halothane anesthesia -> heart sensitive to catecholamine; arrhythmia
epineph standard diluent
1mg/250ml 0.9 NSS
epinephrine IV compatibility (3)
incompatibility (3)
dopamine
dobutamine
diltiazem
(hypotensives)
aminophylline
sodium bicarbonate
other alkaline sol’ns
(deactivates epineph)
epineph ADME
*onset of bronchodilatation
SQ 5-10 min
Inh 1 min
Oral - rapid metabolism in GI, liver (not given orally)
Dist - cross placenta, breastmilk
Metab - adrenergic neuron, degraded by MAO and COMT
Elim - no clinical significance
IM dosage epineph
0.3-0.5 mg
if px is taking amitriptyline/imipramine/beta blocker
give half doses of adrenaline instead of epinephrine
IV epinephrine indications (2)
hypotensive
in cardiac or respiratory arrest (who failed to respond to IV volume replacement & multiple IM epinephrine)
*infusion = 4ug/ml rate of 1ug/min
anaphylaxis != cardiac resuscitation (dosing)
anaph 1:1000 (adults and pedia)
cardiac arrest: 1:10000
ocular symptoms
itching
sneezing
rhinorrhea
intranasal cs & oral AH
decongestants
intranasal anticholinergics & nasal saline irrigation
all
ocular + rhinorrhea (decongestants; a-adrenergic agonist)
rhinorrhea
a-adrenergic agonists may damage mucosa due to ischema -> necrosis. what to do?
selective for a1 receptors less likely to damage
limitation of therapy with nasal decongestants
loss of efficacy
“rebound” hyperemia
worsening of symptoms
on chronic use or when drug is stopped
ephedrine adverse effect
less potent?
what’s similar to this?
CNS
pseudoephedrine -> less tachycardia, inc bp, CNS stimulation
phenylpropanolamine (withdrawn in US due to cardiac effects)
nasal decongestants: use with caution in px (3)
hypertension
prostatic enlargement
taking MAO inhibitor - addictive; toxicity
caveat with topical decongestants even if more selective site of action
how about oral decongestants
used excessively by px -> rebound congestion
oral - less likely ang rebound congestion, but more risk of adverse systemic effects
phenylephrine drug class and effects (3)
a1-agonist
mydriatic (dilate pupil)
topical decongestant
inc bp
- constriction of nasal mucosa
- resist COMT
ephedrine drug class, effects (3)
a/b-agonist
mild stimulant
decongestant
inc bp
- high bioavailability
- resist MAO
- release stored catecholamine
xylometazoline, oxymetazoline drug class, effects (2)
a2-agonist
topical decongestant
hypotension
- promote constriction of nasal mucosa
- congeners of clonidine
