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Neuro II Exam 2 > Adrenergic Drugs > Flashcards

Adrenergic Drugs Flashcards

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1
Q

What do adrenergic drugs do?

A

Modulate adrenergic transmission and primarily control function of sympathetic nervous system

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2
Q

Contrast adrenomimetics vs sympatholytics

A
  • Adrenomimetics/sympathomimetics/drugs activating adrenergic transmission: mimic or promote effects of norepinephrin/epinephrine/dopamine at adrenergic receptors in sympathetic NS
  • Sympatholytics/antiadrenergic/drugs inhibiting adrenergic transmission: prevent effects of norepinephrine/epinephrine/dopamine at adrenergic receptors in sympathetic NS
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3
Q

Describe types of adrenergic receptors

A 
Alpha1: Gq: Increase IP3, DAG
Alpha2: Gi: decrease cAMP
Beta: Gs: increase cAMP
D1 and D5: Gs: Increase cAMP
D2-4: Gi: decrease cAMP
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4
Q

Describe alpha1 receptor activation, tissue, and actions

A

IP3 leads to increase in cytosolic Ca2+.
DAG activates PKC

Most vascular smooth muscle = contraction
Pupillary dilator muslce = contraction (dilates)
Pilomotor smooth muscle = erects hair
Prostate = contraction
Heart = increases force of contraction

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5
Q

Describe alpha2 receptor activation, tissue, and actions

A

Decrease in cAMP and inhibition of PKA

Postsynaptic CNS neurons = multiple actions
Platelets = aggregation
Adrenergic and cholinergic nerve terminals = inhibits transmitter release
Some vascular smooth muscle = contraction
Fat cells = inhibits lipolysis

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6
Q

Beta receptor activation?

A

Accumulation of cAMP

Activation of PKA

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7
Q

Beta1 tissue and actions

A

Heart, juxtaglomerular cells = increases force and rate of contraction. Increases renin release

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8
Q

Beta2 tissue and actions

A

Respiratory, uterine, vascular smooth muscle = relaxation
Skeletal muscle = promote potassium uptake
Liver = activates glycogenolysis

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9
Q

Beta3 tissue and actions

A

Bladder = relaxes detrusor muscle

Fat cells = activates glycogenolysis

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10
Q

D1 and D2 tissue and actions

A 
D1 = smooth muscle = dilates renal blood vessels
D2 = nerve endings = modulates transmitter release
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11
Q

Compare direct-acting adrenergic drugs with indirect-acting

A

Direct-acting: interaction with adrenergic receptors: agonists and antagonists

Indirect-acting: increase or reduce concentration of NE at target receptors

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12
Q

List alpha agonist drugs and receptor affinities

A

Phenylephrine, methoxamine: a1>a2»>B

Clonidine: a2>a1»>B

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13
Q

List mixed alpha and beta agonists and receptor affinities

A

Norepinephrine: a1=a2; B1»B2
Epinephrine: a1=a2; B1 = B2

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14
Q

List beta agonists and receptor affinities

A

Dobutamine: b1>b2»>a
Isoproterenol: b1 = b2»>a
Albuterol, terbutaline: b2»b1»>a

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15
Q

List dopamine agonists and receptor affinities

A

Dopamine: D1 = D2»b»a
Fenoldopam: D1»D2

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16
Q

Describe epinephrine effects on cardiac function

A

Beta1
Increases force of contraction: positive inotropic effect
Increases heart rate
Increases conduction velocity at AV node

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17
Q

Epinephrine effects on vascular tone

A

Beta2 and alpha1
Increases systolic BP
May decrease diastolic BP and total peripheral vascular resistance
Mean arterial pressure often remains unchanged
Significant differences in receptor types found in vascular beds
-skin vessels and mucous membranes: mostly alpha1
-skeletal muscle: alpha1 and beta2
-renal, cerebral: D1 and alpha1

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18
Q

Epinephrine effects on respiratory system

A

Relaxes bronchial muscle: beta2

Decreases bronchial secretion and congestion within bronchial mucosa: alpha1

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19
Q

Epinephrine effects on skeletal muscle, blood glucose, free fatty acids, renin

A

Skeletal muscle
causes muscle tremor: b2
Increases K+ uptake by skeletal muscle: b2
-promotes hypokalemia and decreases K+ excretion by kidneys

Elevates blood glucose levels

  • enhances liver glycogenolysis: b2
  • inhibits insulin release: a2

Increases free fatty acid levels in blood: beta
Increases renin release: b1

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20
Q

Describe norepinephrine effects

A

A1=a2; B1»B2
Potent cardiac stimulant but reduces heart rate
Potent vasoconstrictor
Lacks B2 agonist effects: no bronchodilation and vasodilation
Increases peripheral vascular resistance and blood pressure
Role of baroreflex

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21
Q

Describe effects of dopamine

A

D1=D2»B1»a1

D1 stimulation causes vasodilation
-high density of D1 receptors in renal, cerebral, mesenteric and coronary vessels

Activation of presynaptic D2: suppresses norepinephrine release

Activates B1 in heart at higher doses

At still higher doses stimulates vascular alpha1 AR to cause vasoconstriction

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22
Q

Effects of phenylephrine

A

Alpha agonist. a1>a2»>B
Not a catecholamine, not inactivated by COMT
-longer duration of action
Effective mydriatic and decongestant
Causes severe vasoconstriction and blood pressure elevation
Role of baroreflex in response to phenylephrine

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23
Q

Effects of Clonidine

A

Selective alpha2 agonist. a2>a1»»b
Central effect on alpha2 receptors in lower brainstem area
-decreasing sympathetic outflow
-reduction in blood pressure
-bradycardia (reduces peripheral vascular resistance, decrease heart rate and cardiac output)

Local application produces vasoconstriction

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24
Q

Effects of isoproterenol

A

B1=B2»>A
Nonselective beta agonist
Positive inotropic and chronotropic action, increases cardiac output: B1
Vasodilator, decreases arterial pressure: B2
Causes bronchodilation: B2

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25
Effects of dobutamine
B1>B2, a1 Selective B1 agonist A1 receptor activity (-)isomer agonist at these receptors, while +isomer is a1 antagonist Potent inotropic action Less prominent chronotropic action as compared to isoproterenol
26
Effects of terbutaline, albuterol
B2>B1>>>a Selective B2 agonists Cause bronchodilation and relaxation of uterus
27
Describe indirect adrenergic agonists
Usually more lipophilic compounds (not catecholamines) | Easily penetrate BBB: have significant central effects: CNS system stimulants
28
Effects of amphetamine, methamphetamine, methylphenidate
Mild alerting effects | Improved attention
29
Effects of cocaine
Inhibits transmitter reuptake at adrenergic synapses Peripheral and intense central adrenomimetic action Local anesthetic properties
30
Effects of ephedrine
Releases stored catecholamines with some direct adrenomimetic action Plant constituent Non-catechol -long duration of action -effective after oral administration Nonselective: similar to epinephrine in actions Mild stimulant enter CNS
31
Effects of tyramine
Accumulates in protein-rich foods during fermentation Readily metabolized by MAO in liver (very high first-pass effect) If administered parenterally, affords indirect sympathomimetic action caused by release of stored catecholamines (norepinephrine-like effect)
32
Use of adrenergic agonists on CV conditions to increase blood pressure
Hypotensive emergencies: hemorrhagic shock, overdose of antihypertensives, CNS depressants -Norepinephrine, phenylephrine, methoxamine Chronic hypotension: ephedrine Cardiogenic shock (due to massive acute MI): dopamine, dobutamine
33
Use of adrenergic agonists on CV conditions: heart failure
Short-term use of dobutamine in acute HF | Dopamine in congestive severe HF with reduced renal perfusion
34
Use of adrenergic agonists on CV conditions: hypertension
Alpha-2 agonists for long-term treatment | Fenoldopam in hypertensive emergencies
35
Use of adrenergic agonists on CV conditions: emergency therapy for complete AV block and cardiac arrest
Epinephrine, isoproterenol
36
Use of adrenergic agonists on CV conditions: decongestion of mucous membranes
Phenylephrine, ephedrine, pseudoephedrine
37
Use of adrenergic agonists for bronchial asthma
Beta-2 selective agonists: | Albuterol, terbutaline
38
Use of adrenergic agonists for anaphylaxis (immediate type 1 allergic reaction characterized by respiratory and CV components)
Respiratory component: bronchospasm and upper airway congestion CV component: severe hypotension, cardiac depression Ephinephrine: effective at both components
39
Use of adrenergic agonist for ophthalmic applications
Exam of retina: induction of mydriasis: phenylephrine | Glaucoma: alpha-2 selective agonists: apraclonidine, brimonidine
40
Use of adrenergic agonist for GU applications
Suppression of premature labor: beta-2 agonists: terbutaline Stress urinary incontinence: ephedrine Priapism: alpha-1 agonists (phenylephrine) via injection into penis
41
Use of adrenergic agonist on CNS conditions
Narcolepsy (sudden brief sleep attacks): amphetamines, methylphenidate ADHD (short attention span, learning problems, and hyperkinetic physical behavior): methylphenidate Obesity (central inhibition of appetite and increased energy expenditure): phentermine, ephedrine, amphetamines
42
Cardiovascular adverse effects of adrenergic agonists
Elevation in blood pressure Increased cardiac work may precipitate myocardial ischemia and heart failure: special attention given to elderly pts and pts with hypertension, coronary artery disease, and chronic heart failure Sinus tachycardia and serious ventricular arrhythmias Direct myocardial damage leading to cardiomyopathy May induce sudden cardiac death
43
Central nervous system toxicity of adrenergic agonists
Most of agonist drugs (catecholamines and other polar drugs that do not cross BBB) do not cause CNS toxicity Amphetamine and amphetamine-like compounds cause: insomnia, lack of appetite, anxiety, restlessness, psychoses (paranoid state, hallucinations) Cocaine may cause: convulsions, arrhythmias, hemorrhagic stroke
44
Direct vs indirect adrenomimetic drugs at synapse
Monoamine oxidase (MAO) inhibitors: Selegiline, phenelzine (indirect) Reuptake blockers: Cocaine (indirect) Releasing agents: amphetamines, methylphenidate (indirect) Mixed acting: ephedrine (direct and indirect) Adrenergic receptor agonists (direct)
45
Describe common sites of action for antiadrenergic drugs (direct vs indirect)
Inhibits NE synthesis: metyrosine (indirect) Deplete NE: guanethidine (indirect) Adrenergic receptor antagonists (direct)
46
What are the nonselective alpha receptor antagonists?
Phentolamine | Phenoxybenzamine
47
What are the alpha1 receptor selective antagonists?
``` All end in -osin Prazosin Terazosin Tamsulosin Doxazosin Alfuzosin Silodosin ```
48
Compare competitive alpha antagonist with irreversible alpha antagonist
``` Competitive alpha antagonist: Noncovalent binding to receptor Shorter acting Effect antagonized by high concentration of agonist Ex: phentolamine ``` ``` Irreversible alpha antagonist: Covalent binding to a receptor Longer acting Effect is not antagonized by alpha agonist Ex: phenoxybenzamine ```
49
Alpha antagonist effects on CV system
Decreased peripheral vascular resistance and blood pressure Reflex tachycardia Postural hypotension
50
Alpha antagonist effects on GU system
Relaxation of smooth muscle in prostate | Decreased resistance to flow of urine
51
Alpha antagonist effects on
Relaxation of pupillary dilator muscle (miosis)
52
Alpha antagonist effects on pheochromocytoma
Tumor of adrenal medulla producing catecholamines Excess causes tachycardia, arrhythmias, hypertension Treatment: phentolamine, phenoxybenzamine
53
Alpha antagonist effects on chronic hypertension
Prazosin, terazosin, doxazosin: alpha1 selective Work well in moderate hypertension Generally well tolerated Nonselective alpha-blockers not used
54
Alpha antagonist effects on erectile dysfunction
Combination of phentolamine and nonspecific vasodilator papaverine (injected into penis)
55
Alpha antagonist effects on benign prostate hyperplasia (BPH) to treat chronic urinary obstruction
Tamsulosin Silodosin -greater selectivity for alpha1a than alpha1b -alpha1a most important alpha subtype mediating prostate smooth muscle contraction -effectively relieves urinary obstruction and pain with little effect on blood pressure Prazosin, doxazosin, terazosin also effective
56
Adverse effects of alpha antagonists
Most significant effects are on CVS Seen less with alpha1 selective antagonists Postural hypotension: antagonism of alpha1 in venous smooth muscle Tachycardia Retention of fluid and salt Impaired ejaculation Nasal stuffiness
57
What are the mixed antagonists?
Labetalol (beta and alpha1 antagonist) | Carvedilol (beta and alpha1 antagonist)
58
What are the beta1 and beta2 antagonists?
Propranolol Pindolol Nadolol Penbutolol
59
What are the beta1 selective antagonists?
Metoprolol Betaxolol Acebutolol Atenolol
60
Which beta-blockers are antagonists, partial agonists, inverse agonists?
Antagonists: atenolol, nadolol, propranolol, betaxolol Partial agonists: acebutolol, labetalol, penbutolol, pindolol Inverse agonists: carvedilol, metoprolol
61
Effects of beta-blockers on CV system
``` Heart Negative inotropic effect Negative chronotropic effect Block AV node -slowed atrioventricular conduction -increased PR interval ``` Blood vessels Initially: rise in peripheral vascular resistance Chronic use: decrease in PVR (lowers blood pressure in hypertensive individuals) RAS Inhibit renin release
62
Effects of beta-blockers on respiratory system
Increase in airway resistance
63
Effects of beta-blockers on eye
Reduce production of aqueous humor: reduce intraocular pressure
64
Effects of beta-blockers on metabolic effects
Inhibit lypolysis Increase VLDL and decrease HDL, reduce HDL cholesterol/LDL cholesterol ratio Inhibit glycogenolysis in the liver
65
Effects of beta-blockers on hypertension
Antihypertensive effect is delayed | Both beta-blockers and mixed alpha and beta blockers (Labetaolol, alpha1 and beta blocker) are used
66
Effects of beta-blockers on angina pectoris
Blocking cardiac beta-receptors decreases cardiac work and reduces oxygen consumption Beta-blockers reduce the frequency of anginal episodes and improve exercise tolerance
67
Effects of beta-blockers on myocardial infarction
Long-term use in postinfarction period: prolong surivival Timolol, propranolol, metoprolol Acute phase of myocardial infarction Contraindications: bradycardia, hypotension, acute heart failure, AV block, active airway disease
68
Effects of beta-blockers on cardiac arrhythmias
Effective in ventricular and supraventricular arrhythmias - atrial flutter and atrial fibrillation - ventricular ectopic beats
69
Effects of beta-blockers on heart failure
Effective for treatment of chronic heart failure in selected pts Metoprolol, bisoprolol, carvedilol Contraindicated in acute congestive heart failure
70
Effects of beta-blockers on glaucoma
Mech involves reduction in production of aqueous humor by ciliary body Timolol, betaxolol: blockers w/o local anesthetic activity (propranolol not used)
71
Effects of beta-blockers on hyperthyroidism
Important aspect: excessive catecholamine action on heart Thyroid storm: severe form of hyperthyroidism Tachycardia, supraventricular and ventricular ectopic arrhythmias Propranolol
72
Adverse effects of beta-blockers on CNS
(Switch to more hydrophilic drug) Sedation Sleep disturbances Depression
73
Adverse effects of beta-blockers on respiratory system
(Switch to beta-1 selective) Increase airway resistance Trigger bronchospasm and asthma attack in susceptible indivduals (chronic asthma, COPD, chronic bronchitis)
74
Adverse effects of beta-blockers on CV system
Depression of heart rate, cardiac contractility and excitability (switch to partial agonist) Exacerbation of peripheral vascular disease (switch to beta1 selective)
75
Adverse effects of beta-blockers on lipid profile
(Switch to a partial agonist drug) Chronic use: increase VLDL and decrease HDL (LDL usually not changed, but ratio HDL/LDL cholesterol decreases) Seen with both selective and non-selective B-blockers
76
Adverse effects of beta-blockers on hypoglycemic episodes
(Switch to beta1-selective) May delay recovery form insulin-induced hypoglycemia by inhibiting glucose output by liver Blunt perception of hypoglycemia by these pts (tremor, tachycardia, and nervousness are caused by B-AR activation) Increased incidence and severity of hypoglycemic episodes in pts with diabetes type 1 on insulin Much safer in diabetes type 2 pts who usually do not have hypoglycemic reactions
77
Adverse effects of beta-blockers on abrupt discontinuation of beta-blocker therapy
Increased risk in pts with ischemic heart disease | Gradually taper beta blocker dosing to prevent sympathetic hyper-responsiveness and potential toxicity
78
What is the norepinephrine release inhibitor?
Guanethidine Taken up by reuptake mech Replace norepinephrine in vesciles Causes a gradual depletion of norepinephrine stores Inhibition of norepinephrine release via local anesthetic properties
79
What is the inhibitor of tyrosine hydroxylase
Metyrosine
80
Clinical use of indirect acting antiadrenergic drugs
Chronic hypertension: guanethidine | Pheochromocytoma: metyrosine

Neuro II Exam 2 (6 decks)

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