Sympathomimetics part 2 Flashcards

1
Q

NOREPI is __ to epi at β1, very little β2 actions.
Potent α1 producing intense vasoconstriction in arterial and venous vascular beds

Because is has ver little B2 = no bronchodilating effects!

A

equal

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2
Q

Norepi Increases BP by increasing __ , May trigger the baroreceptor reflex, increased __ can elicit a reflex bradycardia.

A

SVR

SVR

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3
Q

NE released during stress in brain stem’s __ ___, which is the origin of most NE pathways in the brain.
Noradrenergic neurons project from __ __ to the cerebral cortex, limbic system, and spinal cord.

A

Locus ceruleus

Locus ceruleus

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4
Q

NE is a catecholamine & phenethylamine derivative.

Stereoisomer - we use the dextro or levo form?

A

LEVOphed

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5
Q

NE is synthesized in adrenal medulla from the amino acid __, then oxidated to __, then de-carboxylated to __

A

tyrosine
L-DOPA
Dopamine

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6
Q

NE action is followed by signal termination - either by degradation of NE or by NE uptake by surrounding cells.

A

degradation OR uptake

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7
Q

What are the two major urinary metabolites of catecholamine metabolism?

A

VMA and MOPEG

Zach rode his mopeg to the vma’s to get an award for the best skiing wreck of the winter break.

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8
Q

Again, does NE activate B2?

A

No, no bronchodilating properties

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9
Q

Again, how do NE increase BP?

A

Alpha 1 and 2 agonist causing increased SVR

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10
Q

Dopamine is a Phenethylamine derivative that is released by hypothalamus, stimulates the __.

A

Stimulates the CTZ

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11
Q

Of all the dopamine receptors, only d1 and d_ have clinical significance

A

d1 and d2

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12
Q

D1receptor works post synaptically to __

A

vasodilation of renal, mesenteric, coronary, and cerebral blood vessels

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13
Q

D2 receptor works pre synaptically to __

A

inhibits the release of NE, (post-synaptic) weak vasoconstriction

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14
Q

Dopamine acts @
β1 receptors with 3-10mcg/kg/min doses,
α1 @ >10mcg/kg/min doses

A

A portion of dopamine’s + inotrope effect is from release of endogenous NE (indirect actions!)

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15
Q

“Renal Dose Dopamine” 1-3 mcg/kg/min implies dopamine only works at kidneys at this level

A

NOT TRUE

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16
Q

Dopamine inactivated by reuptake via dopamine transporter DAT

A

Enzymatic breakdown by catechol-O-methyl transferase (COMT) and monoamine oxidase (MAO) contributes to ending dopamine effects.

Dopamine may also simply diffuse away from the synapse, and help to regulate blood pressure

17
Q

Dopamine doses

A

2 to 5 μg/kg/min:
binds D1 receptors, dilating blood vessels, increasing blood flow to renal, mesenteric, and coronary arteries
5 to 10 μg/kg/min:
Positive inotropic and chronotropic effects via increased β1 receptor activation. Used in patients with shock or heart failure to increase CO & BP.
10 to 20 μg/kg/min:
Dopamine causes vasoconstriction, increases SVR, and increases BP through α1 receptor activation.

18
Q

ISOPROTERENOL is the Most potent activator of β adrenergic receptors due to substitution of isopropyl group at terminal amine of the beta-phenylethylamine

A

Has no α effects – no increases in SBP directly, increased SBP indirectly from greater CO

19
Q

ISOPROTERENOL is used for greater HR, increased myocardial contractility, cardiac automaticity, bronchodilation, reductions in PVR

A

Use with post heart transplant patients due to de-innervation of the orthotopic heart transplant
Primary use is for bradycardia & heart block.
Isoproterenol causes + chrontropic, dromotropic, & inotropic effects (β1).
Isoproterenol activates all β receptors – not always desirable

20
Q

Isoproterenol Uses/ Contraindications

A

Resistant bradyarrhythmias when pacing is not available
Pharmacologic pacing for torsade de pointes (polymorphic ventricular tachycardia)
Contraindications - angina, pre-existing arrhythmias, tachycardia or AV block caused by cardiac glycoside intoxication. Ventricular arrhythmias due to AV nodal block.
Usual effective dose 0.2-2 mcg/kg/minute

21
Q

Dobutamine- direct stimulation B1 receptors.

A

Dobutamine not as useful in ischemic heart disease because it may increase HR, potentially increasing myocardial oxygen demand

22
Q

DOBUTAMINE Selective β1 adrenergic agonist used to improve cardiac output

A

+ dromotrope… be careful with atrial fibrillation as HR may markedly increase.

23
Q

Dobutamine is given as a racemic mixture of both + & - isomers.

A

The + isomer is a potent β1 agonist

The – isomer is an α1 agonist.

24
Q

Dobutamine Dosing

A

rates typically 2-10 mcg/kg/min

25
Q

PHENYLEPHRINE Synthetic non-catecholamine
Principally α1 direct effect with only a small part via indirect release of NE
Minimal if any β effect

A

Venoconstriction > arterial constriction

differing only by lacking a 4-hydroxyl group on the benzene ring from epi

26
Q

Phenylephrine may impair LV global function when given rapidly to anesthetized patients (1mcg/kg)

A

Can be used to treat PSVT (500mcg bolus)

27
Q

Dexmedetomidine - Like clonidine, agonist of α2 - adrenergic receptors in the brain.

A

imidazole compound

28
Q

Dexmedetomidine has no absolute contraindications but —

A

Caution with boluses due to peripheral α2 -receptor stimulation with resulting hypertension and bradycardia

29
Q

EPHEDRINE - Indirect acting synthetic noncatecholamine

A

Stimulates α and β adrenergic receptors

Endogenous release of NE (indirect) and direct stimulation of adrenergic receptors

30
Q

takes 250X an ephedrine dose to equal an epi dose

A

good to know

31
Q

Vasopressin stored in the posterior pituitary for release into the bloodstream or directly into the brain

A

Not an adrenergic agent
Works on Three arginine vasopressin receptor types

CRNA’s should like AVPR1A best!