Oral boards: Cardiac

Epinephrine

- Class

- MOA

Epinephrine

- Class

- MOA

Class = endogenous catecholamine

MOA

- dose dependent, nonselective adrenergic agonist at B2, B1, A1, A2 (in that order)

- most potent alpha @ high doses

Epinephrine

- Dosing

IV dosing:

- 10 mcg - 1mg

Drip (1-20 mcg/min) (0.01-0.15 mcg/kg/min)

- 1-2 mcg/min = mostly B2

- 4 mcg/min = B1 stimulation

- > 10 mcg/min = alpha + beta

Epinephrine

- O/D

O = immediate

D = ~ 5 mins

Epinephrine

- side effects/considerations

- dilates coronaries + airways via B2 effects

- 1st line tx for anaphylaxis

- can cause arrhythmias + ischemia

- increases HR by accelerating phase 4 of SA node AP

- increases renin release

- increases blood sugar

- decreases K+

Ephedrine

- Class

- MOA

Class = synthetic non-catecholamine

MOA

- mostly indirect acting by stimulating release of endogenous NE

- has SOME direct acting effects

- nonselective for alpha 1 + 2/beta 1 + 2

Ephedrine

- dosing

- 5 - 10 mg IV

- 10 - 50 mg IM

Ephedrine

- O/D

O = seconds

D = ~ 15 mins

Ephedrine

- side effects/considerations

- tachyphylaxis w repeat doses

- MAOI's may potentiate effects = risk of HTN crisis (dont give for 14 days s/p MAOI)

- will NOT work in catechol depleted pts (sepsis)

- caution in pts w active pheo, AS, and recent cocaine use

Phenylephrine

- Class

- MOA

Class = synthetic non-catecholamine

MOA

- selective alpha 1 agonist

Phenylephrine

- Dosing

Bolus:

- 50 - 200 mcg IV q 10-15 mins

Gtt:

- 0.15-0.75 mcg/kg/min

Phenylephrine

- O/D

O = immediate

D = 15 mins

Phenylephrine

- side effects/considerations

- can cause reflex bradycardia d/t BRR

- no tachyphylaxis w repeated doses

- caution in glaucoma b/c can dilate pupils

- great for CAD b/c it increases DBP, which improves CoPP

- caution in pts w AR/MS d/t the bradycardia risk

- may decrease CO d/t the high afterload

Vasopressin

- Class

- MOA

Class = endogenous non-catecholamine

- synthetic ADH

MOA

- directly stimulates V1 receptors in vascular smooth m = vasoconstriction

- V2 stim in kidneys = increased H2O absorption

- blunts NO action of cGMP

Vasopressin

- dosing

Bolus

- 0.5-2 units

Gtt

- 0.01-0.04 units/min

Vasopressin

- O/D

O = < 3 mins

D = < 20 mins

Vasopressin

- side effects/considerations

- caution in CAD d/t vasospasms

- decreases plt aggregation

- causes splanchnic vasoconstriction = good for GI bleeds, but also risk for ischemic bowel

- risk of hyponatermia + seizures d/t water reabsorption

- 1st line tx for refractoy HOTN d/t ACEI/ARBs

Norepinephrine

- Class

- MOA

Class = endogenous catecholamine

MOA

- A1, A2, B1 agonist (in that order)

Norepinephrine

- dosing

Infusion

- 0.01-0.4 mcg/kg/min

Norepinephrine

- O/D

O = immediate

D = ~5 mins after infusion d/c'd

Norepinephrine

- side effects/considerations

- must be given via central line

- potential for tachy/arrhythmias, but LESS than epi

- risk for organ ischemia

- drug of choice in septic shock

- will increase BP, and CO is usually unchanged

- avoid in cardiogenic shock d/t increased afterload + MVO2

- caution w MAOI's + TCA's = reduced NE reuptake = increased SNS stimulation

Esmolol

- Class

- MOA

Class = selective beta blocker

MOA

- competitive antagonist at B1 receptor

- prevents NE/Epi from binding = no increased cAMP, so no increased Ca

Esmolol

- dosing

To blunt SNS response

- 0.5mg/kg IV

Gtt:

- 50-300 mcg/kg/min

Esmolol

- O/D

O = 1 min

D = 9 mins

Esmolol

- side effects/considerations

- fast metabolism d/t RBC esterases

- larger doses can become nonselective

Contraindicated in:

- heart block

- severe brady

- unstable LV failure

Labetalol

- Class

- MOA

Class = non-selective blocker

MOA

- blocks B1 and B2 = no increased cAMP = no increased Ca

- blocks A1 = no increased PLC = no increased Ca

Labetalol

- Dosing

To blunt SNS

- 0.1-0.5 mg/kg

For HTN crisis

- 5-20 mg IV q 10 mins

- max = 300 mg in 24 hrs

Labetalol

- O/D

O = 5 mins

D = 4 hours

Labetalol

- side effects/considerations

- will NOT cause reflex tachycardia

- caution in pts w PVD, RAD, asthma, DM, COPD d/t B2 blockade

- IV potency = 7 beta:1 alpha

- not the DOC to blunt SNS d/t long DOA

Contraindicated in:

- heart block

- severe brady

- unstable LV failure

Metoprolol

- Class

- MOA

Class = selective beta blocker

MOA

- competitive antagonist @ B1 receptors in the heart

- NE/epi cant bind = no increased cAMP = no increased Ca

Metoprolol

- dosing

1-5 mg IV (1mg at a time, titrate to HR response)

- usually ~ 5mg total

1mg IV = 5 mg PO

Metoprolol

- O/D

O = < 5 mins

D = < 4 hrs

Metoprolol

- side effects/considerations

- large doses will become nonselective = bronchoconstriction

- better choice for pts w COPD, RAD, Asthma, PVD, DM d/t no B2 effects

- the perioperative BBlocker of choice

Contraindications

- heart block

- bradycardia

- unstable LV failure

Hydralazine

- Class

- MOA

Class = arterial dilator

MOA

- increases NO release + cGMP = decreases Ca = vasodilation

Hydralazine

- dosing

2.5-20 mg IV

Hydralazine

- O/D

O = 20 mins

D = 4 hrs

Hydralazine

- side effects/considerations

- wait for effects BEFORE redosing!! d/t slower onset time

- mostly an arterial dilator

- BRR tachycardia (caution in those who would not tolerate this)

- long term use = SLE

- not the best choice in acute situation d/t slow onset time

- can decrease CoPP d/t a bigger effect on decreasing DBP vs SBP

Nicardipine

- Class

- MOA

Class = CCB, dihydropyridine

MOA

- binds to alpha 1 subunit of L-type Ca channels

- prevents Ca entry into vascular smooth m

Nicardipine

- Dosing

Infusion:

- 2.5mg/hr, increase by 2.5mg q5 mins

- max = 15 mg/hr

IV bolus

- 100-500 mcg PRN

Nicardipine

- O/D

O = 3 mins

D = 3 hours

Nicardipine

- side effects/considerations

- can cause a BRR tachycardia

- no cardiac depressant effects

- greatest vasodilator of all CCB, esp to coronaries

- SE's = HOTN, HA, angina, flushing

Sodium nitroprusside

- Class

- MOA

Class = nonselective vasodilator

MOA (arterial > venous) is a pro drug

- reacts w Oxyhgb to from Methgb

- methgb breaks down into 5 cyanide ions + NO

- NO = increased cGMP = decreased Ca = vasodilation

Sodium nitroprusside

- Dosing

infusion dosing

- 0.3-10mcg/kg/min

Sodium nitroprusside

- O/D

O = immediate

D = < 10 mins

Sodium nitroprusside

- side effects/considerations

- BRR tachycardia

- may cause BP increase AFTER d/c'd d/t stimulation of renin release

- tachyphylaxis

- risk fo cyanide toxicity, metghbemia

- can cause coronary steal

- attenuates HPV

- caution in AS pts

Nitroglycerin

- class

- MOA

Class = vasodilator

MOA (primarily venodilation)

- generates NO in presence of thio-containing compounds

- NO = increased cGMP = decreased Ca = vasodilation

Nitroglycerin

- Dosing

IV bolus

- 10-20 mcg IV

Infusion

- 0.5-3 mcg/kg/min

Nitroglycerin

- O/D

O = 1-2 mins IV

D = 5-10 mins

Nitroglycerin

- side effects/considerations

- BRR tachycardia

- dilates the coronaries!!

- #1 SE = HA

- prolonged use = tolerance; avoid w drug free period

- cerebral vasodilator

- can relieve sphincter of Oddi spasms

- caution w pts on erectile dysfx drugs (extreme HOTN)