ANS Flashcards
Endogenous catecholamines
Epinephrine
Norepinephrine
Dopamine
Synthetic catecholamines
Isoproterenol
Dobutamine
Synthetic non-catecholamines
Indirect acting: Ephedrine, mephentermine, amphetamines
Direct acting: Phenylephrine, Methoxamine
Selective Alpha 2 agonists
Clonidine, dexmedetomidine
Selective Beta 2 adrengergic agonists
Albuterol, Terbutaline, Ritodrine
All sympathomimetics are ___ ____ derivatives
Beta-phenylethylamine derivatives
Amine group (NH2) side chain
Hydroxy group on the 3,4 carbons of benzine ring (catechol)
*this allows COMPT to metabolize them
Termination of effect of sympathomimetics
Catecholamines: Reuptake- uptake 1 is neuronal reuptake; uptake II is extraneuronal uptake MAO COMPT LUNGS
Non-Catecholamines: MAO Urinary excretion (unchanged)
Receptor agonist: Phenylephrine
a1 > a2»>b
Receptor agonist: Clonidine
a2 >a1»_space;> b
Receptor agonist: Norepinephrine
a1=a2; b1»> b2
Receptor agonist: Epinephrine
a1=a2; b1= b2
Receptor agonist: Dobutamine
b1>b2»_space;>a
Receptor agonist: Isoproterenol
b1=b2»_space;>a
Receptor agonist: Terbutaline/Albuterol
b2»b1»>a
Receptor agonist: Dopamine
D1=D2» b»a
Receptor agonist: Fenoldopam
D1» D2
GCPR and effects: Alpha 1
Gaq= increased Ca= constriction
GCPR and effects: Alpha 2
Gai= decreased CAMP= constriction
GCPR and effects: Betas
Gas- adenylate cyclase= increase CAMP= DILATION and increased contractility and HR
Where are B1 found?
Heart- Increase force and rate of contraction
Kidneys- stimulate renin release
Where are B2 found?
Bronchioles, uterine, vascular, GI, GU- smooth muscle relaxation
Mast cells- Decrease histamine
Skeletal muscles- increase K uptake, dilation, tremor
Liver- glycogenolysis
Pancreas- increase insulin secretion
Adrenergic nerve terminals- increase NE release
Where are A2 found?
Platelets- aggregation Adrenergive presynaptic- inhibits transmitter release (decrease BP and HR) Vascular smooth muscle- contraction GI- relaxation CNS- sedation and analgesia
Where are Alpha 1 found?
Vascular smooth muscle- contraction iris- contraction (dilates- mydrasis) Pilomotor- erects hair Prostate and uterus- contraction Heart- Increase force of contraction
Epinephrine
1-2 mcg/min= B2 4-5 mcg/min= B1 10-20 mcg/min= alpha and beta Onset: 1-2 min IV (5-10 min SQ) Duration: 5-10 min *with moderate dosing, SBP increases-B1, A1; DBP decrease- B2; Map stays the same.
Effects of Epinephrine
Constricts cerebral, coronary, pulmonary. a1- mydriasis; a1,a2- increase humoral outflow; B1 increase aqueous humor; B2 decreased released of histamine, a1- decongestion; *A1 DECREASED RENAL BLOOD FLOW, B1 INCREASED RENIN RELEASE; a1- contraction of urethral sphincter, B2- relaxtion decreases urinary output. B2- relaxation- inhibits labor.
B2- glycogenolysis
Levophed
Hypotension 4-16 mcg/min
Potent alpha and beta-1 effects (minimal B2)
Increased SBP, DBP, MAP (decreased HR baroreceptor response0
Decreased venous return, CO, HR (despite B1 effects)
Dopamine
1-3 mcg/kg/min= Dopamine 1
3-10 mcg/kg/min- Beta 1
>10 mcg/kg/min- alpha
Synergistic with dobutamine to reduce afterload and improve CO (used in heart failure)
Isoproterenol
Equal B1 and B2; increases HR and contractility with decreased SVR. Inc SBP, decreased DBP, decreased MAP.
1-5 mcg/min for heart block and bradydysrythmias
*rapid COMPT, need infusion
Dobutamine
2-10 mcg/kg/min
5mcg/kg/min = A1
Improves CO without increasing HR or BP (good for CHF)
*coronary artery vasodilator
Ephedrine
Indirect and direct at alpha and beta
10-25 mg; 10-50 mg IM
*excreted unchanged in the urine (40%) slowly metabolized by MAO
Phenylephrine
50-200 mcg IV or 20-50 mcg/min infusion
Increase MAP, SBP, DBP, SVR, decrease HR and CO
A1
Venoconstriction > arterial constriction
Albuterol
Selective B2
Preferred choice for bronchospasm
MDI 100 mcg/puff; 2 puffs q4-6 hours; max 16-20 puffs
Other B2 Agonists
Albuterol
Terbutaline- oral, SC or puffs or IV. (for asthma or premature labor)
Salmeterol- doa >12 hours
Ritordine- treatment of premature labor (some B1 effects can increase HR and CO, can cause pulmonary edema)
Direct acting sympathomimetics, non catecholamines
A1 agonists:
Midodrine, Oxymetazoline
A2 agonists:
Clonidine (partial), Dexmedextomidine (full), Methyldopa
Indirect-acting sympathomimetics
Amphetamine, methamphetamine, methylphenidate (Ritalin), Cylert, ADHD meds
Inhibitors of catecholamine storage and reuptake
Reserpine- vesicles don’t store norepi, 5ht, dopamine
Cocaine- prevents reuptake of catecholamines
Alpha agonists
A1»_space;>A2: Prazosin, terazosin, doxazosin
A2= A1: Phentolamine
A2»A1: Yohimbine, Tolazoline
Mixed Alpha and B antagonists
B1=B2 > A1 > A2
Labetalol, carvedilol
Beta Antagonists
B1»_space;> B2: Metoprolol, atenolol, esmolol
B1= B2: Propranolol, Nadolol, Timolol
B2»_space;> B1
Phentolamine
Nonselective; for hypertensive emergencies
30-70 mcg/kg IV
Onset 2 minutes
Local infiltration: 2.5-5.0 mg in 10 ml
Phenoxybenzamine
Binds covalentely, Alpha 1> Alpha 2
Selective alpha 1 blocker
Prazosin, less reflexive tachycardia (pheochromocytoma)
Alpha 2 blocker
Yohimibine, increases release of norepi from post-synaptic neuron; orthostatic hypotension and impotence
Alpha antagonists for BPH
Terazosin and Tamsulosin- long active alpha 1 blocker
Beta adrenergic receptor antagonists specificity
Non selective B1 and B2: Propranolol, nadalol, timolol, pindolol
Cardioselective: metoprolol, atenolol, acebutolol, betaxolol, esmolol
Propranolol
Non- selective. 90-95% first pass. 0.05mg/kg IV or 1-10 mg 90-95% protein bound Metabolized in liver. E1/2T 2-3 hours Decreased clearance of amide LA Decreases pulmonary first pass effect of fentanyl
Beta adrenergic receptor antagonists your patients might be taking?
Timolol- non selective treats glaucoma
Nadolol- E1/2T 20-40hrs take 1x daily
Metoprolol
Selective beta 1 blocker. Prevents ionotropy and chronotropy 60% first pass effect PO: 50-400 mg IV: 1-15 mg E1/2t 3-4 hours
Atenolol
Most selective beta 1 antagonist
E1/2T: 6-7 hrs
Not metabolized in liver, lengthened in renal disease
Useful in cardiac patients with CAD
Betaxolol
Cardioselective B1
E1/2 is 11-22 hrs
single dose daily for HTN, topical for glaucoma, good choice for asthmatics, less bronchospasm than timolol
Esmolol
Selective B1, rapid, short acting 0.5 mg/kg IV (10-180 IV) DOA <15 mins E1/2T 9 minutes, rapidly hydrolyzed by plasma esterases (no effect on sux metabolism) Affects HR without decreasing BP
Labetalol
Combined Alpha and Beta. Beta to Alpha: 7:1 E1/2T 58 hours, prolonged in liver disease Max drop seen in BP 5-10 min after Dose 0.1-0.5 mg/kg *5mg at a time in OR
Atropine
0.2-0.4 mg IV (preop)
0.4-1.0 mg IV (bradycardia)
2mg in 5ml NS via neb (bronchodilation)
Onset 1 minute
DOA: 30-60 min
E1/2T 1.25 hours
80% unchanged via urine
IV Glycopyrrolate
0.1-0.2 mg IV (pre-op and bradycardia) Onset of 2-3 mins DOA: 30-60mins E1/2T: 1.25 hours 80% unchanged via urine
Scopolamine
0.3-0.5 or 5mcg/kg IM (preop)
1.5 transdermal (5mcg/hr x72 hours for nausea)
extensively metabolized with 1% excreted in urine
Ipratropium
MDI- 40-80 mcg 2 puffs
0.25-0.5 via nebulizer
onset 30-90 minutes
Consider in asthmatics, COPD, smokers prior to airway instrumentation
Physostigmine
treatment for central anticholinergic syndrome
15-60 mcg/kg IV repeated as needed q1-2 hours
Muscarinic antagonists:
Bronchodilators
Non-specific M-rec
M3 specific
Bronchodilators: Atrovent, Spiriva
Nonspecific M: Ditropan, Detrol (for overactive bladder)
M3: Enablex, Vesicare (overactive bladder)