Exam 6 - Adrenergic Agonists & Antagonists Flashcards
1
Q
Characteristics of adrenergic agonists
A
- Derivatives of B-phenylethylamine
- stimulate fight/flight
2
Q
Catecholamines
A
- 2 OH groups on ring
- potent at B receptors
- rapid inactivation by MAO/COMT
- cannot give orally (too much COMT/MAO in gut)
- do not enter CNS…too polar
3
Q
Noncatecholamines
A
- only 1 or no OH groups
- longer duration of action
- only MAO breaks it down…not very well
- greater access to CNS….less polar
4
Q
Substitutions on amine Nitrogen
A
- more subs….more affinity for B receptors
5
Q
Epinephrine
A
- Adrenalin
- endogenous neurotransmitter/hormone
- released by adrenal medulla (80%….NE 20%)
- BOTH alpha and beta
- Increases HR/contractility/renin/CO
- constricts skin/viscera vessels
- dilates liver/skeletal muscle vessels
- high dose = constrict (alpha)…low dose = dilate (B2)
- HR up / systolic up…diastolic down / PVR down
- bronchodilation / allergy inhibition
- hyperglycemia (increase glucagon / decrease insulin..alpha)
- Lipolysis (B3)
6
Q
Epinephrine therapeutic uses
A
- Cardiac arrest
- Anaphylactic shock
- Acute asthma attack / bronchospasm
- With local anesthetics….to keep local
7
Q
Epi CPR dose
A
1 mg IV/IO every 3-5 min
8
Q
Epi bradycardia dose
A
2-10 ug/min IV to effect
9
Q
Epinephrine pharmacokinetics
A
- Rapid onset, short duration
- due to MAO/COMT….is a catecholamine
- IM/IV/IO/SQ/inhalation/endotracheal….NOT orally
- excreted by kidney
10
Q
Norepinephrine
A
- Levophed (leave em dead)
- endogenous neurotransmitter of adrenergic nerves
- Alpha and B1
- Intense vasoconstriction
- Increase contractility BUT barrorecpetor reflex….so HR down
- HR down / systolic up…diastolic up / PVR up
11
Q
NE therapeutic uses
A
- Vasodilatory shock
- Hypotension
12
Q
NE dose
A
0.5-12 ug/min to titrated to effect
13
Q
NE pharmacokinetics
A
- lasts 1-2 minutes
- rapidly metabolized by MAO/COMT
- excreted via kidney
- IV ONLY…extravasation cause necrosis…no peripheral veins
14
Q
Dopamine
A
- endogenous precursor to NE…neurotransmitter and hormone
- CNS/adrenal medulla
- D (low= 1-2 ug/kg/min) > B (medium= 2-10) > alpha (high= >10)
- HR up / contractility up
- contracts at HIGH doses
- dilates renal/splanchnic arteries
15
Q
Dopamine therapeutic uses
A
- MAIN drug for cardiogenic/septic shock
- Renal failure…increases renal flow
- Hypotension/heart failure…especially if with renal failure
- NE will decrease renal flow even more
16
Q
Dobutamine
A
- Dobutrex
- synthetic, direct catecholamine
- B1
- Increases CO/HR ( < dopamine)/Contractility ( >dopamine)
- NO PVR effect
- Less increase in O2 consumption
17
Q
Dobutamine therapeutic uses
A
- Increase CO in acute heart failure
- short term “failure to wean” drug
18
Q
Isoproterenol
A
- Isuprel
- synthetic catecholamine
- Nonselective B1 and B2
- Increase contractility/HR
- potent vaso/bronchodilator
- Up HR / zero-little up systolic…down diastolic / down PVR
19
Q
Isoproterenol therapeutic uses
A
- Second choice for cardiac emergency
- bronchospasms during anesthesia
- cardiac stimulant
20
Q
Phenylephrine
A
- Neo-Synephrine
- synthetic Alpha 1
- lasts 20 min (longer than epi/NE)
- constriction
- Up systolic….up diastolic
- Drops HR….due to reflex bradycardia…like NE
21
Q
Phenylephrine theraputic uses
A
- Hypotension
- Tachycardia
- Nasal decongestant if topical/oral
- VERY common to increase SVR and MAP
22
Q
Neo dosing
A
- Start with test dose (50-100 ug/ml)
- LD = 50-500 ug
- IV = 10-15 in 250 ml fluid (40-60 ug/ml)
23
Q
Indirect adrenergic agonists
A
- increase endogenous levels of Epi/NE
- cause release / inhibit reuptake / inhibit degradation
- Amphetamine / Tyramine / Cocaine
24
Q
Amphetamine
A
- reverse NE reuptake channels on presynaptic terminal
- more release of NE