Lecture 41 Flashcards

Adrenergic Agonists 1

1
Q

Arterial Baroreceptors

A
  • Sense arterial pressure indirectly

- Stretch of the elastic arterial walls

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2
Q

Epinephrine

A
  • Adrenaline
  • Released from chromamaffin cells of adrenal medulla (endocrine hormone)
  • EPI simulations all alpha and beta receptors
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3
Q

Beta 1 Mechanism Review: Fight or Flight

A
  • Increased inotropic and chrontropic on heart
  • Dilated coronary vessels
  • Lipolysis to some extent
  • Increases HR and contractility
  • Increases systolic AND diastolic BP
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4
Q

Beta 2 Mechanism Review: Fight or Flight

A
  • Increases blood flow to skeletal muscles and vasodilation
  • Dilates bronchi to increase oxygen intake
  • Increases glycogenolysis in muscle/liver
  • Increases gluconeogenesis in liver
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5
Q

Beta 3 Mechanism Review: Fight or Flight

A
  • Lipolysis

- Relaxes detrusor muscle

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6
Q

Alpha 1 Mechanism Review: Fight or Flight

A
  • Vasoconstriction in skin/mesentery

- Increases systemic BP

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7
Q

PK of EPI

A
  • Administration via injection, intranasal, and topical to eye
  • NOT ORAL (susceptible in liver metabolism)
  • IV injection - slowly over 5-10 minutes during CPR
  • ER use
  • Loses potency after expiration date due to tendency to auto-oxidize (changes from clear to a pink or brown color)
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8
Q

Epinephrine Uses

A
  1. Bronchi dilation
  2. Anaphylaxis
  3. Cardiopulmonary Resuscitation
  4. Direct intracardiac Injection
  5. Circulatory shock following resuscitation
  6. Surgical bleeding
  7. Decrease mucosa congestion
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9
Q

Bronchi Dilation

A
  • Beta 2 receptor activation
  • Treats bronchospasm and severe asthma exacerbation
  • Anaphylaxis ==> Use Epipen Autoinjector
  • Ana-Kit: SC, IM, IV
  • Primatene - OTC inhlaer (D/C due to chlorofluorocarbons)
  • Racepinephrine (Asthmanetrin) - OTC inhaler, temporary relief of mild symptoms of intermittent asthma
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10
Q

EPI: Antagonist of Histamine

A
  1. Vasoconstricts: decreases mucosal edema (alpha-1)
  2. Dilates bronchi (Beta-2)
  3. Stabilizes mast cells - increases histamine release (Beta-2)
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11
Q

Histamine’s Role in Allergy

A
  1. Dilates and increases permeability of capillaries (edema)
  2. Constricts smooth muscle of bronchi
  3. Stimulation of mucus secretions
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12
Q

Cardiac Resuscitation -Target/Drug

A
  • Beta 1 receptor = cardiac

- Ana-Kit used in cardiac resuscitation

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13
Q

Cardiac Arrest Causes

A
  1. Tachyarrhythmias
  2. Bradyarrhythmias (Decrease HR and AC conductance)
  3. Asystole - no HR/contraction
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14
Q

Cardiac Resuscitation Steps

A
  1. First start CPR with electrical defibrillation
  2. EPI and vasopressin used to constrict blood vessels (alpha 1 effect and V1 receptors)
  3. Main purpose of epi/vasopressin is to increases cerebral/myocardial blood flow during CPR
  4. Antiarrhythmic drugs (amiodarone/lidocaine)
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15
Q

Direct Intracardiac Injection

A
  • Only in extreme emergencies

- Risks include: myocardial puncture, coronary artery rupture, pneumothorax

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16
Q

Circulatory Shock

A
  • Can occur after resuscitation
  • IV infuse EPI for symptomatic bradycardia treatment
  • Dopamine is first line preferable
  • EPI increases the changes of spontaneous circulation
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17
Q

Alpha 1 Receptor Vasoconstriction Uses

A
  1. Treats/prevents surgical bleeding when applied topically
  2. Administered with local anesthetics to decrease absorption of local anesthetics from site of injection (decreases systemic toxicity and prolongs effect of anesthetic at site)
  3. Decreases congestion within mucosa
    (EPI activated)
18
Q

EPI Contraindication

A
  1. Hemorrhagic shock, cardiac disease + coronary insufficiency, cardiac arrhythmias
  2. Vasoconstriction
19
Q

Heart Conditions + EPI

A

Detrimental to contraindicated due to:

  1. Increased myocardial oxygen demand
  2. Increase HR
  3. Proarrhythmic potential
  4. Produces vasoconstriction
20
Q

Vasoconstriction + EPI

A
  1. Induced tissue necrosis locally in peripheries and presence of peripheral vascular disease
  2. Contraindicated in cerebrovascular disease to hemorrhages
  3. Hypertension and hyperthyroidism
  4. Diabetes mellitus: hyperglycemia due to increases gluconeogenesis/glycogenolysis
21
Q

Adverse Reactions + EPI

A
  1. Anxiety, N/V
  2. Cardiac arrhythmias including sinus tachycardias , palpitations, hypertension - angina results form increased workload and oxygen demands of heart in predisposed patients
  3. IV injections/infusions leak cause necrosis to occur due to alpha constriction of vessels
22
Q

Phentolamine

A
  • Regitine
  • Alpha receptor antagonist
  • Injected locally to reverse tissue necrosis locally
23
Q

EPI Block Box

A
  • Antidote for peripheral ischemia: Regitine
  • Immediate and conspicuous hyperemic changes (increased blood flow)
  • Give ASAP once extravasation is notices
24
Q

NE

A
  • Acts on postganglionic sympathetic neurons

- Levophed injectable = only one available

25
Q

NE Stimulates…

A
  1. Alpha 1 - vasoconstrictor
  2. Alpha 2 - feedback inhibition of release
  3. Increases HR and contractility
26
Q

NE PK

A
  • Ineffective orally, administration = IV
  • Short duration, rapid inactivation and reuptake at synapse
  • Metabolism by MAO and COMT
  • NE, like EPI/dopamine, doesn’t cross BBB
27
Q

NE CV Uses

A
  1. Acute hypotension - non-volume related hypotension where systolic BP is less than 70 mmHg
  2. Cardiogenic/Septic Shock - use NE, vasopressin, antibiotic therapy, and fluid replacement
28
Q

NE GI Use

A
  1. Upper GI Bleeding - administer intraperitoneally or using a nasogastric tube
29
Q

NE Contraindications

A
  1. Don’t use in patients who are hypovolemic 0 correct volume first
  2. Don’t use with mesenteric thrombosis (increases ischemia)
  3. Don’t use with hypertension/hyperthyroidism
30
Q

NE Adverse Reactions

A
  1. N/V, Anxiety
  2. CV - sinus tachycardia, hypertension
  3. Tissue necrosis at site of injection
  4. Large/repeated doses
    * *Damage due to formation of toxic quinone**
31
Q

Isoproterenol

A
  • Isuprel
  • B1/B2 selective

Mechanisms:

  • B1 - increase in inotropic and chronotropic effects, increases systolic BP
  • B2 - vasodilation, decrease in diastolic CP by direct vasodilation and prevention of histamine and other autocoid release from mast cells (decrease bronchoconstriction and edema)
32
Q

Isoproterenol Uses

A
  1. Cardiac (B1) - Mild/transient episodes of heart block that don’t require a pacemaker or electric shock
  2. Cardiac (B1) - in cardiac arrest and catheterization
  3. Lung (B2) - bronchospasm occuring during anesthesia
33
Q

Dopamine

A

Endogenous neurotransmitter

Dosage Effects

  1. Low dose - vasodilates renal, mesenteric, coronary, and intracerebral vasculature
  2. Moderate dose - stimulation B1 receptors which increases CO and maintains vasodilation effects
  3. High Doses - alpha-adrenergic effects, vasoconstriction
34
Q

PK of Dopamine

A
  1. Admin. continuous IV infusion
  2. Rapid onset, short duration
  3. No BBB, L-dopa does though
  4. Metabolized by MAO and COMT - ~25% converted to NE
35
Q

DA Uses

A
  1. Treats decreased CO, BP, and urinary output that occurs with septic shock, cardiogenic shock, and post-surgical myocardial failure
    * *Gradually increase dose until affect is achieved, D/C slowly to minimize hypotensive response**
  2. Treat hypotension (after resus. or with bradycardia)
  3. Stimulates urine output (with oliguria)
36
Q

DA Contraindications

A
  1. Pheochromocytoma (adrenal tumor)
  2. Uncorrected ventricular fibrillation and tachycardia, tachyarrhythmias
    DA can lead to B-receptor stimulation and indirect release of endogenous NE
    CAUTION WITH CARDIAC DISEASE SINCE IT INCREASES OXYGEN DEMAND
37
Q

DA Adverse Reactions

A
  1. PVC - from B-stimulation of myocardium
  2. Peripheral vasoconstriction and subsequent hypertension from alpha-stimulation and high doses
  3. Hypotension can result from abrupt D/C
  4. N/V by dopamine receptors at chemoreceptor trigger zone (D2 receptor at CTZ)
  5. Avoid leakage of dopamine from IV site since it leads to tissue necrosis
38
Q

Fenoldopam

A
  • Carlopam
  • Selective D1-agonist
  • Short-term treatment of severe hypertension
  • Peripheral and renal arterial vasodilator produces dose-dependent decreased BP and increases in renal plasma flow which stimulates diuresis and natriuresis
  • May cause reflex tachycardia, short onset and duration
39
Q

Catecholamine Drug-Drug Interactions

A
  1. Potentiate actions of catecholamine inhibiting enzymes - MAOIs and COMTIs
  2. Potentiate NE and DA effects by blocking NE uptake pumps - TCAs, Cocaine, Amphetamine
  3. Receptor blockers interfere with postsynaptic catecholamine response
  4. Hyperthyroidism - can increase the number of beta receptors in the heart, so take care when using B-agonists including DA
40
Q

Alpha-blocker Drugs

A
  1. Prazosin

2. Phenothiazines

41
Q

Beta-blocker Drugs

A
  1. Propranolol

2. Metoprolol

42
Q

DA-Blocker Drugs

A

Antipsychotic Drugs