Adrenergic Receptors Agonist And Antagonists Flashcards
What are the adrenoceptors❓
a1: a1A a1B a1D a1L
a1A=a1L
a2: a2A a2B a2C a2D
a2D=a2A
b:
b1
b2
b3
What are the actions of a1 receptors on:
- Vascular smooth muscle
- Pupillary dilator muscle
- Pilomotor smooth muscle
- Vasoconstriction
- Constriction of pupillary dilator muscle (mydriasis)
- Contraction
*Refer to photos
What are the actions of a2
receptors on:
- Adrenergic and cholinergic nerve endings
- Platelets
- Some vascular smooth muscle
- Inhibits transmitter release
- Aggregation
- Vasoconstriction of some smooth muscle
*Refer to photos
What are the actions of b1 receptors on:
- Heart
- Glomerular cells
- ⬆️rate and force of contraction
- Stimulates renin release
*Refer to photos
What are the actions of b2 receptors on:
- Respiratory, uterine and vascular smooth muscle
- Liver
- Pancreatic B cells
- Relaxation of respiratory, uterine and vascular smooth muscle
- Hepatic glycogenolysis
- Stimulates insulin release
* Refer to photos
What are the actions of b3 receptors on fat cells❓
Stimulates lipolysis
List some a1 agonists?
Methoxamine Phenylephrine Mephentermine Metaraminol Midodrine Oxymetazoline Tetrahydrozoline Xylometazoline
What is the principal pharmacological action of a1 agonists?
Vasoconstriction
What is the principal therapeutic uses of a1 agonists?
- Treatment of shock and hypotension
2. Treatment of nasal congestion
What are the adverse effects of a1 agonists?
Hypertension Headaches Reflex bradycardia Excitability Restlessness Dry mouth Sedation
List some a2 agonists?
Clonidine Apraclonidine Brimonidine Guanfacine Guanabenz a-methyldopa dexmedetomidine clenbuterol
What is the principal pharmacological action of a2 agonists?
⬇️sympathetic outflow
⬇️peripheral vascular resistance
⬇️production of aqueous humour
What is the principal therapeutic uses of a2 agonists?
- Adjunct therapy in shock
- Hypertension
- ⬇️sympathetic response from withdrawal from narcotics eg alcohol and tobacco
- Glaucoma
- brimonidine
- apraclonidine
What are the adverse effects of a2 agonists?
Sedation Dry mouth and nasal mucosa Hypotension Bradycardia Impotence Constipation Nausea and gastric upset
List some b1 agonists?
Dobutamine
Denopamine
Xamoterol
What is the principal pharmacological action of b1 agonists?
⬆️rate and force of contraction
⬆️AV nodal conduction
What is the principal therapeutic uses of b1 agonists?
Chronic heart failure
Myocardial infarction
Impaired cardiac function after surgery
What are the adverse effects of b1 agonists?
⬆️BP
Tachycardia
List some b2 agonists?
Intermediate acting: Albuterol Bitolterol Fenoterol Isoetharine Metaproterenol Procaterol Terbutaline Ridotrine
Long acting:
Formoterol
Salmeterol
Salbutamol
List some a1 agonist drugs you’d request for if you needed to treat shock or hypotension
Methoxamine
Phenylephrine
List some a1 agonist drugs you’d request for if you needed to treat nasal congestion
Oxymethazoline
Tetrahydrozoline
Xylometazoline
Naphazoline
Some a2 agonists can be used in treating glaucoma.
List them
Brimonidine
Apraclonidine
Midodrine is a prodrug
True or false
True
Dobutamine is a b1 agonist that _____CO and ______HR
Dobutamine ⬆️CO and has no effect on HR
What are the precautions you would take if you wanted to administer b1 agonist to a pt❓
How is it administered❓
Make sure pt
- Is not hypertensive
- does not have arrhythmias
IV only!
What are the principal pharmacological actions of b2 agonists❓
Relaxation of bronchial smooth muscle
Relaxation of uterine smooth muscle
Activation of other b2 receptors
What symptoms would you be looking forward to alleviate if you administer a b2 agonist❓ (PTU)❓
Asthma
COPD
Acute bronchospasm
Premature labour
Prophylaxis
Premature labour can be well taken care of with which b2 agonist❓
Ritodrine
b2 agonist should be used with caution in which pts❓
Pts with Cardiovascular disease
What are some of the side effects of b2 agonist❓
Headache Anxiety Nausea Muscle tremors Nervousness Palpitations
List some b3 agonists you know❓
Amibegron
Mirabegron
Solabegron
Vibegron
What are some a-non selective antagonists you know❓
Phenoxybenzamide
Phenotolamine
Tolazoline
Ergot alkaloids
What are some a1 selective antagonists you know❓
Prazosin (1st agent)
Teraxosine long half-life)
Doxazosine (long half-life)
Alfuzosin
Tamsulosin
Indoramine
Urapidil
Bunazosin
Trimazosin
Niguldipine
What do a1 antagonists do❓ (PPA)❓
⬇️peripheral vascular resistance
⬆️vasodilation
Relaxation of smooth muscles of bladder neck and prostate
What might prompt you to select a1 antagonist for treatment❓
What are the side effects of a1 antagonist❓
1
Primary hypertension
Urinary retention
BPH
- Postural hypotension
Reflex tachycardia
What are some a2 selective antagonists you know❓
Yohimbine
Imilozan
Idazoxan
What are conditions that could make you decide to administer a2 antagonists❓
Treatment of male sexual dysfunction
Obesity
What are the PPA of a1 antagonists❓
What are the adverse effects❓
- ⬆️sympathetic output
⬆️HR and BP
Activation of a1 and b1 receptors in the heart and peripheral vasculature
- ⬆️HR, BP
Severe tremors
What are some b-non selective antagonists you know❓
Nadolol
Penbutolol
Pindolol
Propranolol
Timolol
Carteolol
Carvedilol
Bucindolol
Labetalol
Yohimbine, a2 antagonist, is the major active compound in what plant❓
Pausinystalia yohimbine
List some b-non selective antagonists that can block a1 receptors
Carvedilol
Labetalol
What are some b1 selective antagonists you know❓
Acebutolol
Atenolol
Bisoprolol
Esmolol (quick onset/short duration)
Metoprolol
Betaxolol
Celiprolol
Nebivolol
What are some b2 selective antagonists you know❓
Butoxamine
What are the principal pharmacological actions of b2 antagonists❓
⬇️HR ⬇️Heart contraction ⬇️CO Slow conduction in AV node ⬆️Refractory period, AV node
Bronchoconstriction
Prolonged hypoglycemia
⬇️Plasma free fatty acids
⬇️HDLs
⬆️LDLs, triglycerides
Hypokalemia
What might prompt you to select b2 antagonist for treatment❓
Angina pectoris Hypertension Cardiac arrhythmias CHF Hypertrophic obstructive cardiomyopathy
Pheochromocytoma
Glaucoma
Hyperthyroidism
Migraine prophylaxis
Substance withdrawal
Variceal bleeding in portal hypertension
What are the side effects of b2 antagonist❓
Bradycardia Bradyarrythmias -ve ionotropic effect ⬇️CO ⬇️AV conduction
Bronchoconstriction*
Fatigue
Sleep disturbances
Prolonged hypoglycemia
Sexual dysfunction in men
Drug interactions
The bronchoconstriction effect of b2 receptors should be of concern in what type of people❓
Asthmatics
COPD
The prolonged hypoglycemic effect of b2 receptors should be of concern in what type of people❓
Hypoglycemics
Diabetics
Membrane stabilization effect is associated with which beta antagonists❓
Propanolol
Acebutolol
Carvedilol
Betaxolol
Intrinsic sympathomimetic activity is strong for which beta antagonist❓
Pindolol
Intrinsic sympathomimetic activity is weak for which beta antagonist❓
Penbutolol
Carteolol
Labetalol
Betaxolol
What are the 3rd generation non-selective beta agents❓
What is their PPA❓
What is their intrinsic sympathomimetic activity❓
What is their multiple mechanism of action❓
1. Carteolol Carvedilol Bucindolol Labetalol
2.
Membrane stabilizating effect
- Vasodilation
4. a1 antagonism b2 agonism Release of NO 🚫Ca2+ channel Opening K+ channels
Alpha1 adrenergic receptors are:
- Coupled to PLC via Gq/11 a-protein
- Increase IP3/DAG
True or false❓
True
Describe the sequence of events for vascular smooth muscle contraction (a1 agonist)
Binding of agonist ⬇️ Activation of PLC by Gq/11 a-subunit ⬇️ Liberation of IP3 and DAG ⬇️ Activation of IP3 receptors by IP3 ⬇️ Release of stored Ca2+ into IC space ⬇️ Increase Ca2+ concentrations ⬇️ Stimulation of smooth muscle contraction
Alpha2 adrenergic receptors are:
- -vely coupled to adenyly cylase via Gai subunit
- Inhibits cAMP formation
True or false❓
True
Describe the sequence of events for inhibition of NT release (a2 agonist)
Binding of agonist ⬇️ Inhibition of adenyly cyclase ⬇️ Reduced cAMP ⬇️ Reduced activation of PKA ⬇️ Reduced phosphorylation of N-type Ca channels on nerve terminals ⬇️ Reduced Ca2+ influx ⬇️ Reduced vesicular uptake of NT
Beta1 adrenergic receptors are:
- Actively coupled to adenyly cylase via G-alpha-s protein
- ⬆️cAMP formation
True or false❓
True
Describe the sequence of events for +ve chronotropy (b1 agonist)
Binding of agonist ⬇️ Activation of adenyly cyclase ⬇️ Increased cAMP ⬇️ Activation of PKA ⬇️ Phosphorylation of Ca2+ channel in SA nodal cells ⬇️ Faster nodal cell depolarization ⬇️ Positive chronotropy
Describe the sequence of events for +ve ionotropy (b1 agonist)
Binding of agonist ⬇️ Activation of adenyly cyclase ⬇️ Increased cAMP ⬇️ PKA-dependent phosphorylation of L-type Ca2+ channels ⬇️ Enhanced Ca2+ influx ⬇️ Increased release and storage of Ca2+ in SR ready for release through ryanodine receptors
Beta2 adrenergic receptors are:
- Actively coupled to adenyly cylase via G-alpha-s protein
- ⬆️cAMP formation
True or false❓
True
Describe the sequence of events for vascular smooth muscle relaxation (b2 agonist)
Binding of agonist ⬇️ Activation of adenyly cyclase ⬇️ Increased cAMP ⬇️ Activation of PKA ⬇️ Phosphorylation and inactivation of myosin light chain kinase MLCK ⬇️ Reduced affinity of MLCK for Ca-calmodulin ⬇️ Reduced activity of MLCK ⬇️ MLCK 🚫phosphorylate myosin light chain ⬇️ Reduced smooth muscle contraction.
Describe the sequence of events for vascular smooth muscle contraction (a2 agonist)
Binding of agonist ⬇️ Inhibition of adenyly cyclase ⬇️ Reduced cAMP ⬇️ Inhibition of PKA ⬇️ Activation of MLCK ⬇️ Vascular smooth muscle constriction
