ANS Pharm: Dilators, PDEIs, Vasopressin Flashcards
T/F:
Direct acting vasodilators relax arteries
True
without systemic or local constrictor mechanisms or Ca channels
VARY on effects on arteries, arterioles and veins
PDEIs cause smooth muscle relaxation where?
- heart
- lungs
- genitals
PDEIs cause smooth muscle relaxation by increasing levels of
cAMP & cGMP
T/F:
Vasopressin is synthesized in the poserior pituitary
False
hypothalamus
When to use vasopressin
when catecholamines and fluids dont work
Goal BP when using direct vasodilators
below their baseline
NTG
Low dose vs high dose
low dose: venodilate; little effect on SVR
high dosE: arteriole dilation, ↓SVR, reflex tachycardia
Why is NTG first line for cardiac ischemia?
- improves the balance of myocardial O2 supply and demand (direct coronary dilator + systemic effects)
- dilates both normal & stenotic coronaries, preventing vasospasm
NTG cause severe hypoTN in these cases
- hypovolemia
- sildenafil (nitric oxide liberator)
NTG exerts its action via the liberation of ___, a vascular dilator.
nitric oxide
NTG is a nitric oxide ___.
Nipride is a nitric oxide ___.
NTG = liberator
Nipride = donor
NTG is used in MI but Nipride is not. Why?
Nipride = coronary steal
(redistribute blood away from ischemic tissue)
coronary steal
vessels to ischemic areas dilate to the max, so blood flow diverts to nonischemic tissue
NTG vs Nipride
which has more reflex tachycardia & why?
Nipride
more arteriole dilation
thus, nipride will also increase O2 consumption
How to treat reflex tachycardia from Nipride
B1B
Nipride Metabolism produces…
- cyanide
- binds to Hgb = methgb; binds to sulfur = thiocyanate
Nipride dose
MAX dose 500 mcg/kg
MAX rate 2 mcg/kg/min
Toxicity varies, thus maintain a high index of suspicion.
T/F:
Hydralazine will not decrease preload.
True
it doesnt dilate venous capacitance vessels
decreases SVR but not preload
T/F:
Use a B1B to treat reflex tachycardia from hydralazine
True
HDZ produces vasodilation in …
cardiac, cerebral, splanchnic, and renal vasculature
decreases SVR but not preload
Must give this direct vasodilator with a B1B
minoxidil
strong, direct vasodilation
Why dont we use minoxidil for HTN anymore?
- hypertrichosis (hair growth)
- salt and water retention
- pericardial effusion (rare)
PDE
whats the difference between 3, 4 & 5?
- 3: affects both
- 4: cAMP
- 5: cGMP
PDEI agents by class
- 3: milrinone, cilostazol
- 4: roflumilast, apremilast, ibudilast
- 5: sildenafil, tadalafil, vardenafil
PDEIs location of action
3: both; dilate peripheral
4: ↑cAMP (airways, skin, immune)
5: ↑cGMP (lungs, penis)
How do PDEIs affect the lungs?
3: airway smooth muscle relaxation
4: airway smooth muscle relaxation
5: pulm vasodilate & decrease pulm. artery pressure
Why are PDE3s called inodilators?
increase inotropy and relax airway & vascular smooth muscle
milrinone, cilostazol
PDE___ inhibitors vasodilate peripheralaly to treat intermittent claudication & prevent platelet aggregation (DVT prophylaxis)
3
milrinone, cilostazol
PDE__ inhibitors may cause ventricular arrhythmias d/t increasing cAMP and Ca
3
Ideal for weaning from cardiopulmonary bypass
milrinone
- inotrope, A& V dilation
- block platelet aggregation
- decrease inflammation from the bypass
milrinone is ___ x more potent than amrinone, replacing it.
15-20
Nonspecific PDEIs
theophylline, methylxanthine
mild dilation of the airway smooth muscle and reduce inflammation
Theophylline
increases the levels of cAMP in the airways
(asthma and COPD)
vasopressin and oxytocin are similar _____
nonapeptides
Vasopressin’s receptors
V1: SVR
V2: antidiuretic
V3: pituitary; modulate autocoids
autocoids: biological factors acting like “local” hormones
How does GA & neuraxial anesthesia affect vasopressin?
decreases plasma [ ] of stress hormones, including vaso
so giving vaso can rapidly increase BP via V1
Vasopressin dose
bolus (1 - 2 units)
infusion 0.01 - 0.1 unit/ minute
rapidly onsets and lasts 10 - 30 minutes.
vasopressin
healthy vs SNS/RAAS dysfxn
- healthy & conscious: little effect on BP due to reflex inhibition of efferent SNS
- SNS or RAAS axis dysfunction: activates V1 receptors and may restore BP
T/F:
In distributive shock, Vaso, neo and norepi are suitable options.
true
Which receptors do our pressors affect?
Which pressor is suitable for pulm HTN?
vasopressin
PVR = pulm vas resistance?
PDE__ is useful in inflammatory states
4
NTG
I guess both NTG and nipride are donors
