Lecture 41 Flashcards
Adrenergic Agonists 1
1
Q
Arterial Baroreceptors
A
- Sense arterial pressure indirectly
- Stretch of the elastic arterial walls
2
Q
Epinephrine
A
- Adrenaline
- Released from chromamaffin cells of adrenal medulla (endocrine hormone)
- EPI simulations all alpha and beta receptors
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
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
5
Q
Beta 3 Mechanism Review: Fight or Flight
A
- Lipolysis
- Relaxes detrusor muscle
6
Q
Alpha 1 Mechanism Review: Fight or Flight
A
- Vasoconstriction in skin/mesentery
- Increases systemic BP
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)
8
Q
Epinephrine Uses
A
- Bronchi dilation
- Anaphylaxis
- Cardiopulmonary Resuscitation
- Direct intracardiac Injection
- Circulatory shock following resuscitation
- Surgical bleeding
- Decrease mucosa congestion
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
10
Q
EPI: Antagonist of Histamine
A
- Vasoconstricts: decreases mucosal edema (alpha-1)
- Dilates bronchi (Beta-2)
- Stabilizes mast cells - increases histamine release (Beta-2)
11
Q
Histamine’s Role in Allergy
A
- Dilates and increases permeability of capillaries (edema)
- Constricts smooth muscle of bronchi
- Stimulation of mucus secretions
12
Q
Cardiac Resuscitation -Target/Drug
A
- Beta 1 receptor = cardiac
- Ana-Kit used in cardiac resuscitation
13
Q
Cardiac Arrest Causes
A
- Tachyarrhythmias
- Bradyarrhythmias (Decrease HR and AC conductance)
- Asystole - no HR/contraction
14
Q
Cardiac Resuscitation Steps
A
- First start CPR with electrical defibrillation
- EPI and vasopressin used to constrict blood vessels (alpha 1 effect and V1 receptors)
- Main purpose of epi/vasopressin is to increases cerebral/myocardial blood flow during CPR
- Antiarrhythmic drugs (amiodarone/lidocaine)
15
Q
Direct Intracardiac Injection
A
- Only in extreme emergencies
- Risks include: myocardial puncture, coronary artery rupture, pneumothorax
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
17
Q
Alpha 1 Receptor Vasoconstriction Uses
A
- Treats/prevents surgical bleeding when applied topically
- Administered with local anesthetics to decrease absorption of local anesthetics from site of injection (decreases systemic toxicity and prolongs effect of anesthetic at site)
- Decreases congestion within mucosa
(EPI activated)
18
Q
EPI Contraindication
A
- Hemorrhagic shock, cardiac disease + coronary insufficiency, cardiac arrhythmias
- Vasoconstriction
19
Q
Heart Conditions + EPI
A
Detrimental to contraindicated due to:
- Increased myocardial oxygen demand
- Increase HR
- Proarrhythmic potential
- Produces vasoconstriction
20
Q
Vasoconstriction + EPI
A
- Induced tissue necrosis locally in peripheries and presence of peripheral vascular disease
- Contraindicated in cerebrovascular disease to hemorrhages
- Hypertension and hyperthyroidism
- Diabetes mellitus: hyperglycemia due to increases gluconeogenesis/glycogenolysis
21
Q
Adverse Reactions + EPI
A
- Anxiety, N/V
- Cardiac arrhythmias including sinus tachycardias , palpitations, hypertension - angina results form increased workload and oxygen demands of heart in predisposed patients
- 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
NE Stimulates...
1. Alpha 1 - vasoconstrictor
2. Alpha 2 - feedback inhibition of release
3. Increases HR and contractility
26
NE PK
- 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
NE CV Uses
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
NE GI Use
1. Upper GI Bleeding - administer intraperitoneally or using a nasogastric tube
29
NE Contraindications
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
NE Adverse Reactions
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
Isoproterenol
- 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
Isoproterenol Uses
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
Dopamine
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
PK of Dopamine
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
DA Uses
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
DA Contraindications
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
DA Adverse Reactions
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
Fenoldopam
- 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
Catecholamine Drug-Drug Interactions
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
Alpha-blocker Drugs
1. Prazosin
| 2. Phenothiazines
41
Beta-blocker Drugs
1. Propranolol
| 2. Metoprolol
42
DA-Blocker Drugs
Antipsychotic Drugs
