Lecture 2: Adrenergic Pharmacology Flashcards
Which class of receptors are adrenergic receptors?
G protein-coupled (GPCR)
Which catecholamines do adrenergic receptors target?
1) Norepinephrine
2) Epinephrine
Do adrenergic receptors stimulate the PNS or SNS?
SNS and activates different G-proteins
List the tissues (4) affected by ⍺1 receptors
- Most vascular smooth muscle
- Heart
- Prostate
- Pupillary dilator muscle
How does an α1 receptor affect most vascular smooth muscle?
HIGH yield
Vasoconstriction
What is the G protein for an α1 receptor?
Gq
How does an α1 receptor affect the heart?
LOW yield
Increase force
How does an α1 receptor affect the prostate?
LOW yield
Contraction
How does an α1 receptor affect the pupillary dilator muscle?
LOW yield
Pupil dilation
List the systems (2) affected by the ⍺2 receptors
- Postsynaptic CNS
- Presynaptic ANS
⍺2=Decreases sympathetic tone
How does an α2 receptor affect the postsynaptic CNS?
HIGH yield
Decreases SNS tone
How does an α2 receptor affect the presynaptic ANS?
HIGH yield
Decreases NT release
What is the G protein for an α2 receptor?
Gi
List the tissues (2) affected by the β1 receptors
- Heart
- Juxtaglomerular cells
What are the G proteins for a β1 receptor?
Gs, Gi
How does a β1 receptor affect the heart?
HIGH yield
Increases force and rate
How does a β1 receptor affect the juxtaglomerular cells?
HIGH yield
Increases renin release = retains fluid
List the tissues (4) affected by β2 receptors
- Skeletal muscle blood vessels
- Bronchial smooth muscle
- Liver
- Uterus
What are the G proteins for a β2 receptor?
Gs, Gi
How does a β2 receptor affect skeletal muscle blood vessels?
HIGH yield
Relaxation
How does a β2 receptor affect the bronchial smooth muscle?
HIGH yield
Relaxation
How does a β2 receptor affect the liver?
HIGH yield
Glycogenolysis and gluconeogenesis = increases blood glucose
How does β2 receptors affect the uterus?
LOW yield
Relaxation
List the tissue affected by the β3 receptors
Low yield
Adipose tissue (fat cells)
What are the G protein for β3 receptors?
Gs
How does β3 receptor affect adipose tissue?
LOW yield
Increases Lipolysis
Which organs (4) receive adrenergic synapses?
- Cardiac muscle
- Smooth muscle
- Gland cells
- Nerve terminals
Adrenergic receptors have sympathetic responses. Explain what occurs to the:
- Pupils
- Heart rate and contractility
- Respiratory rate
- Digestion
- Blood flow to muscle
- Urination
- Dilates pupil
- Increase heart rate, contractility
- Increase respiratory rate (dilates bronchi)
- Inhibits digestion
- Diverts blood flow to muscles (by vasoconstriction/dilation)
- Inhibits urination
What are the different agonist drug classes (4) of Adrengeric receptors
- ⍺1 agonist
- ⍺2 agonist
- Non-selective agonist (β1+β2)
- β2 agonist
Which drug is an α1 agonist?
Phenylephrine (vasoconstriction)
Which drugs are α2 agonists?
- Clonidine
- Methyldopa = decrease SNS tone
Which drugs (2) are non-selective β agonists (β1 + β2)?
- Isoproterenol
- Dobutamine
Which drug is a β2 agonist?
- Albuterol (dilates bronchial smooth muscle)
List the antagonist drug classes of Adrenergic receptors (5)
Antagonist: opposite effect
- Non-selective ⍺ antagonist
- ⍺1 antagonist
- Non-selective β antagonist (β blockers)
- β1 antagonist (β blockers)
- Mixed ⍺/β antagonists
Which drug is a non-selective α antagonist (blocks α1 and α2)?
- Phentolamine (vasodilation & increases HR)
Which drug is an α1 antagonist?
Prazosin
Which drug is a non-selective β antagonist (β blocker)?
β=olol
Propranolol
β1 antagonist= decreased HR
β2 antagonist=Bronchoconstriction
Which drugs (2) are β1 antagonists (β blockers)?
β=olol
- Atenolol
- Metroprolol
β1 antagonist= derease HR
List the drugs that are β blockers
- Propranolol (non-selective)
- Atenolol (β1)
- Metroprolol (β1)
all antagonist
Which drugs are mixed α1/β antagonists?
-lol: mixed
- Carvedilol
- Labetalol
What is the oral usability of epinephrine?
completely ineffective
Is the duration of action of epinephrine long or short? And explain why?
Short, b/c the structure of epi includes a catechol which gets metabolized quickly by COMT (↑ COMT sensitivity)
COMT: catechol-O-methyltransferase
Does epinephrine have good or poor penetration of the CNS?
poor d/t the high polarity of the structure (canNOT cross barrier)
Why is phenylephrine better than epinephrine as a ⍺1 selective agonist?
- More stable and is not broken down as fast (↓COMT sensitivity)
- Higher ⍺ selectivity compared to epinephrine which has mixed ⍺/β selectivity
Explain the mechanisms of action of ⍺1 agonist.
Drug: Phenylephrine
- Stimulation of ⍺1
- Induce contraction of smooth muscle
- Vasoconstriction of most vascular muscle
- Decrease mucosal edema
What is the primary effect of α1 agonist?
Drug: Phenylephrine
vasoconstriction of most vascular smooth muscle
What are the clinical uses of α1 selective agonists? What are the effects?
Drug: Phenylephrine
● Nasal congestion = decreases inflammation markers
● Hypotension = vasoconstriction = increases BP
● Hemorrhoids = vasoconstriction = stops inflammation of markers to swollen/inflamed veins
● Dilates pupils
What are the adverse effects of phenylephrine?
⍺1 agonist
- Angina
- Anxiety
- Bradycardia
- Tissue necrosis
- HTN
What are the contraindications of phenylephrine?
Contraindications- Underlying diseases
⍺1 agonist
● Vfib
● Tachycardia
● HTN
What are the interactions of phenylephrine?
Interactions-Substances that affect the drug
⍺1 agonist
- MAO inhibitors
- MOA breaks down NE, if pt is taking a MOAI w/ the drug phyenyleprine it will increase the level of NE in the body and ↑↑↑ vasoconstriction
MAO-monoamine oxidase
Drug
Pheylephrine:
- Type (class)
- Effect
- Treatment
- Side Effects
- Contraindication
- Interactions
- Type (class): ⍺1 agonist
- Effect: Vasoconstriction
- Treatment: Nasal cong., hypotension, hemorrhoids
- Side Effects: Angia, Bradycardia, HTN, Necrosis
- Contraindication: Vfib, Tachy, HTN
- Interactions:MAOI
List the drugs that are ⍺2 selective agonists
- Clonidine
- Methyldopa
Stimulation of the α2 receptors in the medulla has what type of effects?
Sympatholytic
- No reflex tachycardia
- Decrease overall NE release through stimulation of pre-synaptic receptors
What are the net effects of α2 agonists?
● Decreased BP
● Decreased HR
● Decreased cardiac output
Activate Gi (inhibitory)