6 - Adrenergic Agonists & Antagonists Flashcards
What drug class/categorization?
Tamsulosin
indoramin / urapidil
Alpha Adrenergic Receptor ANTAGONIST
A1-Selective
What is
EPINEPHRINE REVERSAL?
Since Epi stimulates Both a-NE & b-NE receptors…
but the dominant effect = ↑BP
- *Alpha Effect (↑BP)**
- *OVERWHELMS**
- *B-NE effect** (Vasodilation -> ↓BP)
if EPI + a-NE ANTAGONIST are admin together –> lowered BP
What drug class/categorization?
EPINEPHRINE
ADRENERGIC AGONIST
Direct-Acting & A1/A2/B1/B2 non-selective
Catecholamine:
not orally, degraded by COMT & MAO
Beta Antagonist
Respiratory System Efects
Blockade of B2 Receptors in Bronchial Smooth Muscle:
↑Airway Resistance
Treatment of:
Angina / CHF following MI
Preferred are:
Selective B1 Antagonist = Metoprolol
What drug class/categorization?
Metoprolol** + **Esmolol
Beta Adrenergic Receptor ANTAGONIST
2st Gen = B1-Selective
What drug class/categorization?
Reserpine
NE ANTAGONIST
- *Inhibit VMAT2**
- depletes NT stores* –> ↓BP
not used often due to depression
What drug class/categorization?
Entacapone
ADRENERGIC AGONIST
Indirect Acting
COMT inhibitor
What Receptor?
Pancreatic Islets = INHIBITS Insulin Release
α2-Adrenoceptor Activation
found on BOTH :
PRE-synaptic neurons & POSTsynaptic cells
liver cells / plateles / smooth muscles of BV’s & CNS neurons
What Receptor?
Externam Bladder Sphincter = Urine Retention
Genitilia = Ejaculation
α1-Adrenoceptor Activation
alpha 1 = more CONTRACTION
What Receptor?
- *GI Tract & Smooth Muscle Walls = RELAXES**
- *(PRE-sympathetic Effect)**
α2-Adrenoceptor Activation
found on BOTH :
PRE-synaptic neurons & POSTsynaptic cells
liver cells / plateles / smooth muscles of BV’s & CNS neurons
What drug class/categorization?
Bisoprolol** + **Betaxolol
B-Olol
Beta Adrenergic Receptor ANTAGONIST
B1-Selective
Bisoprolol = 2nd gen
Betaxolol = 3rd Gen
What drug class/categorization?
Selegiline
ADRENERGIC AGONIST
Indirect Acting
MAO inhibitor
What drug class/categorization?
Cocaine
ADRENERGIC AGONIST
Indirect Acting
- *Uptake Inhibitor**
- Impair re-uptake of release catecholamines into sympathetic neurons*
What drug class/categorization?
EPHEDRINE
ADRENERGIC AGONIST
Mixed Acting
A1/A2/B1/B2 & Releasing Agent
Non-Catecholamine:
resist MAO oxidation
What Receptor?
Sympathetic Nerve Terminals = INHIBITS NorEpinephrine Release
α2-Adrenoceptor Activation
found on BOTH :
PRE-synaptic neurons & POSTsynaptic cells
liver cells / plateles / smooth muscles of BV’s & CNS neurons
What drug class/categorization?
-ZOSINS
Prazosin / Terazosin / Doxazosin
Alfuzosin / Bnazosin
Alpha Adrenergic Receptor ANTAGONIST
A1-Selective
Without A2-NE Blockade:
less TachyCardia & Palpitations
What Receptor?
- *GI Tract**
- *Relax Muscular Motility**
α1-Adrenoceptor Activation
alpha 1 = more CONTRACTION
- *Adrenergic Agonist**
- *Catecholamine Properties**
Metabolism:
inactive derivatives are formed
mainly metabolized by Hepatic COMT , some in BRAIN
MAO for some NT’s released from vesicles in nerve terminal
NOT GIVEN ORALLY
IV / IM / Topical / Sprays
What Receptor?
Skeletal Muscle Cells = Tremor / Glycogenolysis (HYPERglycemia)
β2-Adrenoceptor Activation
B2 = more RELAXATION
What drug class/categorization?
Nadolol** / **Sotolol** / **Timolol“3-letter +olol, except for esmolol”
levobunolol / metipranolol
Beta Adrenergic Receptor ANTAGONIST
1st Gen = Non-Selective
What drug class/categorization?
Clonidine
ADRENERGIC AGONIST
Also Guanabenz
Direct-Acting & a2-Selective
↓BP
through central action ↓NE
What drug class/categorization?
Labetalol** + **Bucindolol
Beta Adrenergic Receptor ANTAGONIST
NON-Selective
3rd gen
What Receptor?
FAT CELLS = Lipolysis
TGs –> FFA’s
Fat Cells = THERMOGENESIS in skeletal muscle
β3-Adrenoceptor Activation
What drug class/categorization?
Yohimbine
Alpha Adrenergic Receptor ANTAGONIST
A2-Selective
What Receptor?
Eye = ↓reduces production of aqueous formation
by decreasing CaMP
α2-Adrenoceptor Activation
found on BOTH :
PRE-synaptic neurons & POSTsynaptic cells
liver cells / plateles / smooth muscles of BV’s & CNS neurons
What Receptor?
- *Eye Pupil**
- *Mydriasis (Dilation) / Raises Eyelid**
α1-Adrenoceptor Activation
alpha 1 = more CONTRACTION
- *Adrenergic Agonist**
- *DIRECT ACTING**
- *ONLY Ephedrine + NE** –> activate BOTH A+B receptors
- NE has LOW affinity for b2 receptors*
PhenylEphrine –> A1
Clonidine –> A2
Dobutamine –> B1
Tertbutaline –> B2
What Receptor?
Eye = Increased flow of AQUEOUS HUMOR
by increasing cAMP
β2-Adrenoceptor Activation
B2 = more RELAXATION
What drug class/categorization?
Atenolol** + **Acebutalol
“A - olol’s”
Beta Adrenergic Receptor ANTAGONIST
2st Gen = B1-Selective
Denervation Supersensitivity
Adrenergic Nervous System = Receptor REGULATION
–motor nerve to effector organ is cut
–can be skeletal muscle or autonomic effector
–nerve allowed to degenerate
–no transmitter binding
–proliferation of receptors
–muscle gradually becomes extremely sensitive to neurotransmitter
–Example: restoring the secretion of acid from the stomach following vagotomy (severing the vagus nerve)
Adrenergic Agonist
Non-Catecholamine Properties
- not a catecholamine*
- does NOT have 2 -OHs on Phenyl Ring*
Metabolism
- *MAO** for ephedrine / phenylephrine
- *Some RESIST Oxidation by MAO** = longer duration of action vs catecholamines
ORAL
What drug class/categorization?
Celiprolol** + **Betaxolol** + **Nebivolol
Beta Adrenergic Receptor ANTAGONIST
B1-Selective
3rd Gen
Beta Antagonist
w/ Alpha Antagonist Activity
Labetolol / Carvedilol
LESS TACHYCARDIA
useful in patients with:
Chronic Heart Failure
What drug class/categorization?
IsoProterenol
ADRENERGIC AGONIST
Direct-Acting & B1/B2 non-selective
What drug class/categorization?
NorEpinephrine
ADRENERGIC AGONIST
- Direct-Acting &** A1/A2/B1 *non-selective
- no B2 target like Epi*
Catecholamine:
not oral / COMT + MAO metabolism
What Receptor?
Blood Vessels = Vasoconstriction
Arterioles & Veins
α1-Adrenoceptor Activation
alpha 1 = more CONTRACTION
What Receptor?
Brain (medulla) = INHIBITS Sympathetic outflow
α2-Adrenoceptor Activation
found on BOTH :
PRE-synaptic neurons & POSTsynaptic cells
liver cells / plateles / smooth muscles of BV’s & CNS neurons
Beta Antagonist
Ocular Effects
Blockade of B-receptors @ EYE
↓IntraOcular Pressure
reduction in aqueous humor production
Preferred:
Non-Selective Timolol & Levobunolol
&
Selective B1 Antagonist Betaxolol
What Receptor?
Blood Platelets = Aggregation
α2-Adrenoceptor Activation
found on BOTH :
PRE-synaptic neurons & POSTsynaptic cells
liver cells / plateles / smooth muscles of BV’s & CNS neurons
What Receptor?
Sweat = Apocrine Secretion
Skin (Pilomotor) = Goosebumps
α1-Adrenoceptor Activation
alpha 1 = more CONTRACTION
What Receptor?
HEART
SA node = ↑Firing Rate
Ventricular Myocardium = ↑Force of Contraction
AV node = ↑conduction Velocity
β1-Adrenoceptor Activation
responsible for HEART EFFECTS
b2 may contribute but are LESS important than B1
What Receptor?
Spleen Capsule = Expels RBC
α1-Adrenoceptor Activation
alpha 1 = more CONTRACTION
- *Adrenergic Agonist**
- *Mixed-Acting**
Indirectly Release NE & Directly Activate Receptors
Ephedrine
nasal decongestant / access CNS
Pseudoephedrine
less potent than ephedrine in producing: tachycardia / ↑BP / CNS stim
What drug class/categorization?
OXYMETAZOLINE
ADRENERGIC AGONIST
Direct-Acting & A1/A2 non-selective
Adrenergic Agonist
Indirect-Acting
↑NE or ↑Epi Availability
in the synapse to stim. adrenergic receptors
Amphetamine –> fascilitate NE release
Cocaine –> impair Re-uptake of catecholamines
Entacapone –/–> block COMT
Selegiline –/–> block MAO
What drug class/categorization?
Phentolamine** / **Phenoxybenzamine
Alpha Adrenergic Receptor ANTAGONIST
NON-Selective
A1 Antagonist + A2-NE blockade:
stimulation of B1-NE receptors –> Tachycardia & Palpitations
What drug class/categorization?
Amphetamine
ADRENERGIC AGONIST
also TYRAMINE
Indirect Acting
Releasing Agent
fascilitate NE release from sympathetic nerve endings
What Receptor?
Kidney = RENIN RELEASE
(juxtaglomerular cells)
β1-Adrenoceptor Activation
responsible for HEART EFFECTS
b2 may contribute but are LESS important than B1
What Receptor?
- *Detruser Muscle Bladder** = Relaxes
- *INCREASES bladder capacity & prevents urination**
β3-Adrenoceptor Activation
What Receptor?
Uterine Smooth Muscle (Pregnant) = Relax
Bladder Wall = Relax
β2-Adrenoceptor Activation
B2 = more RELAXATION
What drug class/categorization?
PHENYLEPHRINE
ADRENERGIC AGONIST
Direct-Acting & a1-Selective
NON-catecholamine
resist MAO oxidation –> longer duration of action
What Receptor?
Bronchial Muscles = Relaxes
receptors present but nerve innervation is SPARSE ~ indirect
β2-Adrenoceptor Activation
B2 = more RELAXATION
What drug class/categorization?
P - olol’s
All starting with P:
Penbutolol / Pindalol / Propranolol
Beta Adrenergic Receptor ANTAGONIST
1st Gen = Non-Selective
What Receptor?
Liver = GlycoGenolysis
HYPERglycemia
BOTH
α1-Adrenoceptor Activation
alpha 1 = more CONTRACTION
β2-Adrenoceptor Activation
B2 = more RELAXATION
Beta Antagonist
w/ Partial AGONIST = ISA Activity
ISA = Intrinsic Sympathomimetic Activity
Useful in pts where:
- *Bradycardia is undesirable** (HTN & ANGINA)
- *Abnormalities in Plasma Lipids**
Ex.
PINDOLOL / ACEBUTOLOL / CARTEOLOL
What drug class/categorization?
Carvedilol + Carteolol
Beta Adrenergic Receptor ANTAGONIST
NON-Selective
3rd gen
What Receptor?
Skeletal Muscle Arterioles = VasoDILATION
Cardiac Muscle Arterioles = VasoDILATION
β2-Adrenoceptor Activation
B2 = more RELAXATION
What drug class/categorization?
Metyrosine
NE ANTAGONIST
- *Inhibit Tyrosine Hydroxylase**
- competitive inhibition* –> rate limiting step in catecholamine synth.
↓BP by reducing synthesis of:
↓dopamine ↓NE ↓Epi
What drug class/categorization?
TERTBUTALINE
ADRENERGIC AGONIST
Direct-Acting & B2-Selective
relieves bronchoconstriction
What drug class/categorization?
Dobutamine
ADRENERGIC AGONIST
Direct-Acting & B1-Selective
↑HR & ↑CO
Beta Antagonist
CV System Effects
Chronically for ↓BP
- *Heart (B1):**
- *-NEG inotropic effect / chronotropic effect**
- SLOWED* AV node conduction
Treatment of:
Angina / CHF following MI
Beta Antagonist
Metabolic & Endocrine Effects
Chronic Use of B-Antagonist
associated with:
↑VLDL & ↓HDL
both UNFAVORABLE in CV disease