Adrenergic Agonist - Drug Flashcards
What are the Adrenergic receptors
Alpha (A1, A2)
Beta (B1, B2, B3)
Location of A1 receptors
Vascular smooth muscle UB sphincter Intestinal Smooth muscle Liver : glycogenolysis and cholesterol synthesis Radial iris muscle Prostate smooth muscle
Location of A2
Presynaptic Adrenergic nerve terminal Lipocytes Platelets - increase in platelet agreegation Beta cells of pancreas Vascular smooth muscle
Decrease in aqueous humor production
Location of B1
Heart
Juxtagromerular cells
Increase in Lipolysis
Location of B2
GIT Bronchial smooth muscle Uterus smooth muscle Pancreatic beta cells Liver Skeletal muscle
Increase in aqueous humor production
Increase in potassium uptake
B3?
Lipolysis in adipose tissue
Bladder mid area of detruso muscle
Skeletal muscle: thermogenesis
Order of potency if Adrenergic receptors and their agonist for Beta receptors
Isoproterenol > Epinephrine > NE
Order of potency of Adrenergic receptors and their agonist for Alpha receptors
Epinephrine > NE > Isoproterenol
Dopamine receptors
D1, B1 (alpha1 at high doses), D2
D1: relaxes renal smooth muscle
Dobutamine receptors
D1, B1 alpha1
Mainly beta 1 receptor
Epinephrine receptors
A1, A2, B1, B2
NE receptors
A1, A2, B1
Isoproterenol receptors
B1, B2
How are adrenergic agonist classified
Direct ( cathecolamines and selective Agonists)
Indirect and mixed
What are the directly acting cathecolamines
NE E Dopamine Dobutamine Isoproterenol
What are the selective agonists
Alpha1, alpha2 and beta2 agonists
Use of epinephrine
- Anaphylactic shock DOC
- Asthma
- open angle glaucoma: constriction of ciliary body blood vessels
- Increase duration of local Anesthesia
S/e of epinephrine
Arrhythmia
Pulmonary edema
Hemorrhage
CNS disturbance
Use of NE
Septic Shock
Hypotension
Never for asthma
Causes reflex bradycardia
Use of Isoproterenol
Emergency tx of heart block and severe bradycardia
Bronchial asthma
Electrophysiologic evaluation of tachyarrhythmia
S/e of Isoproterenol
Tachycardia
Arrhythmia
Palpitations
Coronary insufficiency due to no alpha effect
Drug of choice for cardiogenic and hypovolumic shock
Dopamine
Use of Dobutamine
Diagnostic cardiac Stress test
Short term management of heart failure with cardiogenic shock
It has a short half life so should be given with normal saline/glucose
Examples of alpha 1 agonists
Phenylephrine
Methoxamine
And other zolines
Main use of alpha 1 agonist
NASAL congestion
The zolines are mostly used as topical nasal decongestant
Examples of alpha 2 agonists
Methyldopa
Clonidine
Tizanidine
Guanfacine
Methyldopa?
Treat HTN in pregnant woman and in renal dysfunction pts
S/E -hemolytic anemia
- hepatitis
- drug induced lupus
- hyperprolactinemia
Clonidine?
Uses
- Essential HTN (HTN urgency)
- ADHD
- Tourette syndrome
- withdrawal symptoms from opiates and benzodiazepines
Examples of beta 2 selective agonist
Albuterol: fast acting asthma/Copd Sulbutamol Salmeterol: long duration asthma/Copd Formoterol: Metaproterenol Terbutaline + ritudrine : uterine relaxation and bronchospasm in asthma
Use of B2 selective agonist
Asthma
Examples of in direct acting adrenergic agonists
Amphetamime
Tyramine
Doc for ADHD
Amphethamine - methylphenidate
Use of in direct acting adrenergic agonists
ADHD
Narcrolepcy
Obesity
Depression
Use and example of mixed acting drugs
Ephedrine or pseudoephedrine
Used as a nasal decongestant and causes bronchodilation
Urinary incontinence
Hypotension
Cocaine
An indirect sympathomimetics
Used to confirm Horner syndrome as it causes mydriasis in intact SNS
Cocaine intoxication + beta blocker =coronary vasospasm
Dopamine application
For unstable bradycardia and shock
Increase hr and bp (at high dose)
Fendolpam ?
Use and s/e
Adrenergic agonist
Use: hypertensive crises, vasodilator, post-op HTN,
S/e - natriuresis, hypotension, tachycardia, headache, flushing
Fenoldopam receptors
D1
Increase HR and CO
Decrease BP via vasodilation
Use of Phenylephrine
Nasal decongestant
Mydriasis: ocular procedures
Ischemic priapism
Vasoconstrictor: hypotension
Tizanidine
A selective A2 agonist
Use- relief of spasticity
S/e- hypotension, weakness , Xerostomia
Midodrine
A direct sympathomimetic that acts on A1 receptor
Midodrine use and s/e
Use- autonomic insufficiency
Postural hypotension
S/e - exacerbate supine hypertension
Amphetamine use
ADHD
Obesity
Narcolepsy
S/e of Clonidine
CNS Depression Bradycardia Hypotension Respiratory depression Miosis Rebound HTN with abrupt cessation
