I. Vasopresser & Inotropes Flashcards
_____ & ____ were the first vasopressors synthesized.
Dopamine & Vaspopressin
Most sympathomimetics are derived from the parent compound ____.
Beta-Phenylethylalamine
Catecholamine have a hydroxyl substitution on the ____.
Benzene ring
The most basic catecholamine ____, is the precursor for both NE & Epi.
Dopamine
A lack of N-substitution indicates a lack of ____. However, bulky side chains indicates the opposite.
Beta activity
No N-substitution: Phenylephrine and NE = No Beta
Side-Chains: Isoproterenol & Dobutamine = Beta
End result of inotropes is to:
Positively influence the interaction (influx) of Calcium with actin and myosin in the cardiac myocyte
Beta 1 receptor MOA IOT increase INOTROPY:
- Gs membrane protein activated
- Activates Adenylyl Cyclase
- Activates cAMP
- Activates Protein Kinase A
- Increases probability Calcium channels open
- Calcium leaves SR & enters mycocardial/muscle cell
- Increased force of contraction (inotropy) & speed of contraction (chronotropy)
The vasodilation from PDEI is due to ____ .
.cAMP promoting vascular smooth muscle relaxation
reflex VD to accommodate increase in HR - per Weirich
*PDEI inhibit the breakdown of cAMP by PDE3. Increased cAMP enhances Calcium release from the SR and increases the force generated by actin-myosin.
Digoxin increases ____ by inhibiting ____.
- cytosolic Calcium
-Na/K ATPase on the cell membrane
Most vasopressors exert their effects via ____ receptors.
Alpha 1
What is common vasopressor that does not work on alpha 1?
Vasopressin (VA receptors)
All vasopressor drugs work by what MOA:
- Gq cell membrane activated
- Activates Phospholipase C
- Hydrolyzes PIP2 to IP3 & DAG
- IP3 increases Calcium release from SR & DAG activates Protein Kinase C to increase Calcium influx
- More calcium influx leads to increase in vascular smooth muscle tone
What does Phospholipase C do?
Hydrolyzes PIP2 to IP3 & DAG
What does IP3 do?
Increases Calcium release from SR
What does DAG do?
Activates protein kinase c to increase Calcium influx
What does protein kinase c do
Increases calcium influx
Generally vasopressors & intropes have a short/long half-life.
Short
T/F: Generally vasopressors/inotropes are rapidly metabolized.
True
usually run as infusions/titrated
Two compounds that metabolize (by methylation) catecholamines:
- COMT
- MOA
Epinephrine is secreted by
Adrenal medulla
Epinephrine Clinical uses
Epi clinical considerations (causes):
- Cardio: Increase BP, HR, CO, PP, MAP
- CNS: Increase CBF
- Resp: Bronchodilation
- Other: Hyperglycemia, Hyperlipidemia, Arrhythmias, Increase CMRO2
Catecholamines are broken down into:
Sugars (hyperglycemia)
Epinephrine concentration & dosing
1 mg/cc Epi hydrochloride
100 mcg/cc cardiac Epi
500 mcg auto-injector (Epi Pen)
ACLS: 1 mg IVP
HR/BP IVP: 10 mcg
Anaphylaxis: 0.3-1mg
Infusion: 0.05 - 0.2 mcg/kg/min
Isoproterenol (Isuprel) activates what receptor/s?
Beta 1 & Beta 2 non-selective
hint: isoproterenol like a strong ephedrine without alpha 1 vasoconstriction
T/F: Isoproterenol only has chronotropic effects.
FALSE
Both chronotropic and inotropic
Beta 2 agonists can cause what S/E (Desirable and Undesirable)
Desirable:
- Bronchodilation
- Tx Hyperkalemia by reducing plasma Potassium concentrations
Undesirable
- Smooth Muscle relaxation = peripheral vasodilation
- Reflex Tachycardia
- Tremor
Beta 2 receptors exist in the peripheral vasculature
Beta 2 agonists used to be used after ____ but now have been replaced by pacemakers.
Cardiac transplantation
Isuprel concentration
0.2 mg/cc
Isuprel infusion dose
1-5 mcg/kg/min
Isuprel clinical outcomes:
- increased HR
- inotropy
- lusitropy
- Bronchodilation
*was orginally used to treat asthma but was replaced by Selective Beta 2 Agonists (e.g., Albuterol)
Main indication for Isoproterenol
Symptomatic Bradycardia
(Bradycardia so low, BP is also low and unable to compensate)
____ is a profound vasoconstrictor (alpha 1»alpha 2, beta 1)
Levophed (NE)