ANS pharmacology and pathophysiology Flashcards
how is phenylephrine metabolized
MAO
2 examples of mixed function alpha and beta agonists
labetalol
carvedilol
cholinergic agonists (3)
nicotine
bethanechol
physostigmine
direct vasodilators/nitrodilators (3)
nitroprusside, NTG, hydralazine
does PAP increase with phenylephrine
yes d/t pulmonary vasoconstriction and increase in venous return
in the event of a neo OD, what is the drug you give and the drug you AVOID
give: a2 antagonist such as phentolamine
avoid: beta antagonists- can cause pedema
elimination half life of clonidine
8 hours
elimination half life of dexmedetomidine
2 hours
MOA of clonidine
inhibits NE release causing vasodilation and diminishing sympathetic outflow, decreasing HR and BP
sedation via locus coeruleus
pain modification and analgesia via dorsal horn of SC
clinical uses for clonidine (3)
treating HTN
controlling opiate and nicotine withdrawal manifestations
dx of pheochromocytoma
isoproterenol and
airway resistance
metabolism
receptor binding
gtt dose
primary use
airway resistance: decreased
metabolism: COMT
receptor binding: B1>B2 (.015-.15mcg/kg/min)
primary use: drug pacing. less commonly used now
dobutamine and
airway resistance
metabolism
receptor binding
primary use
airway resistance: no change
metabolism: COMT
receptor binding: B1>B2>A1 (2-20mcg/min)
primary use: cardiogenic shock, stress test
epinephrine IV infusion dose
.01-.2mcg/kg/min
systemic effects of catecholamines include
NE receptors it effects
mostly A1 and B1, minimal B2
IV infusion dose of NE
.1-.22mcg/kg/min
NE is first line therapy in
distributive shock
isoproterenol is derived from
dopamine
short acting B2 agonist inhalers include (3)
albuterol
levalbuterol
terbutaline
long acting B2 agonist inhalers include (2)
salmeterol
formoterol
which adrenoreceptor agonist is metabolized by the liver
ephedrine
what is the alpha antagonist family of drugs usually used to treat (4)
HTN
HF
BPH
pheo
MOA of phenoxybenzaprine and use/route of admin
non selective non competitive alpha antagonist that blocks NE and epi, lowering PVR and BP
HR may increased d/t increase in free, unbound NE
almost exclusively used in pheo’s preop to decrease BP
PO!!
what terminates the clinical effect of phenoxybenzaprine
since its irreversible, only the synthesis of new receptors can terminate its effect
best tx for phenoxybenzaprine induced severe hoTN
vasopressin and fluids.
MOA of phentolamine and route of admin (and what reflex it elicits)
noncompetitive non selective alpha antagonist
action can be overcome using an alpha agonist though such as neo or NE
potent rapidly acting vasodilator that causes baroreceptor mediated reflex tachycardia and should be used with caution in CAD patients
IV!!
DOA of phenozybenzaprine versus phentolamine
phentolamine has a much shorter half life of <10 minutes
phentolamine clinical use
can be used to tx extravasation from NE or epi
phentolamine has an affinity for which random receptor
5HT- causes stomach acid secretion and mast cell degranulation
prazosin receptors, MOA, SE
highly selective a1 receptor antagonist with an affinity for a1>a2 1000:1
decreases PVR in arterioles and veins, which increases venous capacitance and decreases preload and BP with little change in HR
SE: postural/orthostatic HoTN
3 analogs of prazosin (a1 selective antagonist) include
terazosin
doxazosin
tamsulosin
terazosin as compared to prazosin
less potent, longer acting, mainly used to tx prostate hypertrophy
doxazosin and tamsulosin as compared to prazosin
weaker vascular effects, primarily used in treating prostate hypertrophy. anesthetic induced HoTN can still be exacerbated
yohimbine receptor affinity, MOA, uses (5)
selective a2 adrenergic antagonist
increases PSNS activity and decreases SNS activity
used for ED, athletic performance, weight loss, HTN, diabetic neuropathy
propanolol receptor affinity, MOA, SE
nonselective B1/B2 antagonist that inhibits actions of NE, epi, dopa, dobut, and isoproterenol
possesses membrane stabilizing effects at high doses which means it also acts as an anti arrhythmic
SE: B2 related: bronchoconstriction, hypoglycemia, peripheral vascular constriciton. may aggravate raynaudus
(selective: A-N. non selective: O-Z. alpha: not -olol)
non selective beta adrenergic antagonist examples include (5)
carvedilol
pindolol
nadolol
sotalol
timolol
(selective: A-N. non selective: O-Z. alpha: not -olol)
non selective BB with very long half life
nadolol
non selective BB with simpathomimetic effects
pindolol–>weak beta agonist effects, associated with less HR slowing/HoTN
(selective: A-N. non selective: O-Z. alpha: not -olol)
metoprolol receptor selectivity, MOA, uses (4), SE
B1
limits HR increase, useful in patients with ischemic disease
used in patients with angina, HF, afib, HTN
(selective: A-N. non selective: O-Z. alpha: not -olol)
esmolol receptor selectivity, uses, onset and DOA,
B1 selective
uses: preventing acute increases in HR intraop
onset/DOA: swift onset, DOA <15 min, can titrate to effect
(10-80mg bolus or 50-330mcg/kg/min)
(selective: A-N. non selective: O-Z. alpha: not -olol)
atenolol receptor selectivity, MOA, uses, onset, DOA
receptor selectivity: B1 receptor antagonist, synthetic
uses: prevents increase in HR, decreases electrical conductivity and inotropy from release of NE
increases cardiac work and decreases O2 demand
DOA: 25-200mg BID to reach full effect in 1-2w (IV or PO)