6.2 Adrenergic Meds Flashcards
What are the A1 agonists?
Phenylepherine
Milodrine
What are the indications and SA of phenylpherine?
selectively stimulates A1 receptor, short half life (2-3 hr) used to maintain BP
If just want vasocontriction (HR ok) use phenylephrine/neosynephrin
ALSO in nasal decongestants (OTC sudafed)- controls congestion by vasoconstriction
SA- high BP, so don’t give with HTN
What are the indications and SA of milodrine?
Prodrug, Selective to A1. Used for pt with poor autonomic fxn (eg parkinsons)
Eg orthostatic hypotension, maintains BP;
SA- Black box warning- causes supine HTN
What are the subcategories of A2 agonists?
Central acting
Peripheral acting
What are the indications for clonidine?
Lower BP
alpha-2 receptors in CNS suppress outflow of sympathetic activity lower BP
Vasoconstriction nasal decongestant
What are the indications for clonidine?
HTN
Reducing diarrhea in DM pts w/ autonomic neuropathy
Relieve w/d sxs – narcotics, alcohol, and tobacco addiction decr craving
** 100% bioavailability PO
What are the side effects of clonidine?
Dry mouth
Sedation
Sexual dysfunction
Caution: w/d rxn follow abrupt d/c of long term therapy
What is brimodinine used for?
Alpha-2 selective reduce prod of aqueous humor
Lower intraocular pressure (i.e. open-angle glaucoma)
What is guanfacine used for?
Alpha-2 selective (more than clonidine) -- central Lower BP ER formulation (Intuniv®) -- for ADHD
What is guanabenz used for?
Centrally acting alpha-2 agonist
Extensively metabolized by liver = many DDI
What is methydopa used for?
Centrally acting antihypertensive
Metabolized to alpha-methyl-NE (in brain) activate alpha-2 in CNS lower BP
Used with pregnanct PTs to lower BP- centrally acting HTN
What is tizanidine used for?
Central acting alpha-2 stimulator
Muscle relaxant tx muscle spasticity d/t spinal or cerebral dz
What subcategories of Beta agonists are there?
Non-selective
B1 selective
B2 selective
** Can be dose-dependent
What is isoproterenol used for?
Receptor?
Non-selective Beta agonist, relaxes all smooth muscle, esp. RESP and GI. for asthma
What is dobutamine used for? Receptor?
B1 selective
+ inotrope, increase cardiac output, with less reflex tachycardia
What is levalbuterol used for? Receptor?
B2 selective
Bronchial dilation
What is Terbutaline used for? Receptor?
Asthma
Tocolytics- prevents smooth muscle contractions, e.g. in pregnancy
What is metaproterenol used for? Receptor?
B2
Tx asthma
Less beta-2 selective than albuterol or terbutaline more prone to cardiac stimulation
Resistant to COMT
What receptor for albuterol? Use?
B2
Asthma
What is levalbuterol used for?
R-enantiomer of albuterol
Tx asthma, COPD
B2
What does pirbuterol target?
B2
What is formoterol used for?
Receptor?
Long duration Bronchial dilation may persist for 12hrs
Tx: Asthma and COPD
What is anformoterol used for?
R,R) enantiomer of formoterol
Twice as potent as Formoterol
What is levodopa used for? receptor?
Dopamine agonist
Treatment of Parkinson’s disease or prolactinemia
Converts to dopamine stimulate dopamine receptors
What is fenoldopam used for? Receptor?
D1 agonist peripheral vasodilation
Treatment of severe HTN (ICU med)
What are the 4 mechanisms of indirect-acting sympathomimetics?
Displace storage- Drug comes in, displaces neurotransmitter from vesicles that store them, so when signal for release comes, cause excessive release
Inhibit reuptake
MAO Inhibiter
COMT inhibitor
What are examples of indirect sympathomimetics that displace storage?
“amphetamine-like” = “displacers”
Ex: Amphetamine, methamphetamine, phendimetrazine (bontril), and methylphenidate
What are examples of indirect sympathomimetics that inhibit uptake?
NE transport inhibitor
Ex:
Atomoxitine (Strattera) – ADHD – selective for NE reuptake transporter
Sibutramine (Meridia) – weight loss – serotonin and NE reuptake inhibitor
Duloxetine – chronic pain, fibromyalgia – SNRI
Cocaine – local anesthetic – dopamine reuptake inhibitor at the “pleasure centers” in the brain – highly abuse
What are the many applications of sympathomimetics?
Treatment of Acute hypotension or shock (i.e. maintaining BP)
Ex: Levophed (norepinephrine); Neo-synephrine (phenylephrine)
Chronic orthostatic hypotension
Hypertension – Centrally acting alpha-2 agents
Inducing local vasoconstriction – decongestant
Bronchial dilation
Anaphylaxis
Mydriatic agent (i.e. phenylephrine)
Tocolytics – suppress premature labor
Weight loss
Narcolepsy – i.e. amphetamine, methamphetamine
ADHD
What is an alpha blockade? What causes it?
When alpha receptors stimulated, cause vasoconstriction, so when blocked, cause vasodilation in arterioles and vains
= lower BP and vascular resistance (afterload)
If BP too low with these meds, body will attemot to compensate, up HR, …. Keeps building until pt crashes
SA- reflex tachycardia- autonomic reflex kicks in, hr increases
Orthostatic HTN- causes peripheral vasculature to be less responsive to vasoconsteiction
Decreases resistance to flow of urine… promotes urinary outflow
What is prazosin used for? Receptor?
Blockade of alpha1 receptors in arterioles and veins
No reflex tachycardia d/t alpha 1 selective
Good PO absorption – 70% bioavailability
95% protein bound; T1/2 = ~3hrs
What is terazosin used for?
Receptor?
Less potent than prazosin
High specificity for alpha-1 receptors
>90% bioavailability; T1/2 = 12hrs
Tx: HTN, BPH
What do -osin meds do?
A1 blocker
What is yohimbine? Receptor?
Competitive alpha-2 blocker
Found in bark of Pausinytalia yohimbe and Rauwolfia root
Structure resemble reserpine
Enters CNS incr BP and HR (opposite to clonidine)
Also blocks 5HT
Tx: male sexual dysfunction – less conclusive than PDE5 inhibitors
What is phenooxybenzamine?
Receptor?
covalent bond to receptor irreversible blockade
Treatment of pheochromocytoma (adrenal tumor secrete lots of catecholamines)
What is phentolamine? receptor?
A2 blocker
Indications:
Pheochromocytoma
Extravasation necrosis from alpha agonists
HTN crises follow abrupt w/d of clonidine
Caution: in PUD enhance GI secretion d/t histamine release
SE:
Hypotension
Tachycardia
Arrhythmias
MI
What are the general effects of Beta blockers?
Lower BP
Increase airway resistance
Reduce intraocular pressure
Selectivity is dose-dependent
What are the B1 selective Beta blockers?
-olol
BBEAAM - We’ll have a list of drugs
What is notable about acebulol and esmolol?
Acebulol- B1 blocker and partial agonist– When binds to receptor, blocks the receptor, but stiumulates it a little= won’t lower BP as much
Esmolol- T1/2 10min!! Use if need a short acting B1 antagonist
What is propranolol used for?
Used off-label for panic attacks, anxiety; anti-arrythmic; migraine prophylaxis; hyperthyroid
What is labetolol used for?
partial agonist and A1 selective
What are side affects of beta blockers?
Bradycardia Mild sedation Cold hands Vivid dreams Depression – rare Nonselective agents – worsen preexisting asthma Depressed myocardial contractility and excitability Cautious in decompensated HF
What happens with beta blockers and asthma? heart failure?
With asthma- B2 blockers cause broncho constriction asthma exascerbation
Can case/worsen heart failure if used in decompensated HF
