Pharm - Adrenergic Agents Flashcards
Adrenergic agents
= Direct sympathomimetics - Epi - NE - DA = Indirect sympathomimetics - Ephedrine - cocaine = Adrenergic agonists - phenylephrine - clonidine - isoproterenol - albuterol = Adrenergic antagonists - methyldopa - phenoxybenzamine - prazosin - propranolol - metoprolol
Epinephrine
MOA
- low dose: beta-agonist
- incr heart rate and contractility -> incr CO and systolic BP
- beta2-agonism -> relax vascular and respiratory smooth muscle -> bronchodilator (and mild decr in diast BP)
- hi dose: alpha-agonist
- vasoconstriction -> incr BP (syst and diast)
USE:
- cardiac arrest and severe hypotension
- bronchospasm in asthma and anaphylaxis
- wide-angle glaucoma when administered as ophthalmic solution
SIDE FX:
- HTN, arrhythmia, MI, pulm edema, headache, anxiety
OTHER: given with local anesthetics to decrease systemic absorption and thus increase concentration at desired site
Norepinephrine
MOA
- potent alpha and beta-1 agonist
- alpha -> vasoconstriction -> incr BP (syst and diast)
- beta-1 -> incr contractility (causes incr HR too, but concurrent incr in BP causes reflex bradycardia, so no change in HR actually observed)
USE:
- pressor in emergency tx of severe hypotension and shock
SIDE FX
- angina, MI, arrhythmia, decr renal blood flow
Dopamine
MOA
- hi dose: alpha-1 agonist -> vasoconstriction -> incr BP (syst & diast)
- med dose: beta-1 agonist -> incr HR and contractility (incr CO)
- low dose: D1 agonist -> incr renal perfusion
USE: pressor to tx hypotension and shock
SIDE FX: arrhythmia, angina, HTN, nausea
OTHER: Dobutamine is a beta-1 agonist used for decompensated CHF or cardiogenic shock
Ephedrine
MOA
- stim release of NE and Epi; also direct stim of alpha- and beta-
- overall increase in BP (syst & diast), bronchodil, and incr in CO
- stim CNS causing insomnia, decr appetite, and improved athletic performance
USE: nasal decongestion (also pseudoephedrine)
SIDE FX: HTN, tremor, anxiety, arrhythmia,
OTHER: Amphetamine enters CNS and stim release of NE, Epi, and dopamine. Leads to decr appetite and insomnia. OD -> psychosis, arrhythmia, seizure, death
Methylphenidate derivative of amphetamine used for narcolepsy and ADHD in children
Cocaine
MOA
- block Na/K-ATPase -> prevent reuptake of NE, serotonin, DA -> euphoria
- vasoconstriction -> cardiac ischemia
- block V-gated Na chan -> local anesthetic
USE: ENT surg local anesthetic
SIDE FX: HTN, abuse, cardiac ischemia, arrhythmia, and infarct, seizure, paranoia
OTHER: Reserpine inhib neuron storage of NE, DA, serotonin. in past: tx HTN, but caused depression and parkinsonism
Guanethidine inhib NE release: in past tx HTN, but causes orthostat hypotension -> shock
Phenylephrine
MOA - alpha-1 agonist -> vasoconstriction and pupil dilation USE - severe hypotension and shock - tx nasal congestion - produce mydriasis (retinal exam) SIDE FX OTHER: Midodrine is alpha-1 agonist to tx hepatorenal syndrome and orthostatic hypotension
Clonidine
MOA
- alpha-2 agonist (vasomotor center of medulla) -> decr central adrenergic activity (NE) with a resulting decrease in vasoconstriction and a decr in CO and HR
USE: tx HTN
SIDE FX: rebound hypotension
OTHER: use in pt with renal disease (no decr in renal blood flow)
Isoproterenol
MOA
- beta-1 and -2 agonist -> incr HR and contractility (incr CO, slight decr syst BP); peripheral vasodilation (overall decr MAP and diast BP); bronchodilation
USE
- tx torsades de pointes (with Mg)
- tx cardiac arrest or complete heart block
SIDE FX
OTHER: Fenoldopam is a D1 agonist -> splanchnic and renal vasodilation -> tx severe HTN
Albuterol
MOA
- beta-2 agonist -> bronchodilation; transcellular shift of potassium into cells
USE
- tx asthma
- hi dose: tx hyperkalemia
SIDE FX
OTHER: Sameterol: long acting beta-2 agonist (prevent asthma attack)
Terbutaline, ritodrine: beta-2 agonist -> reduce uterine contraction in preterm labor; tx bronchospasm in status asthmaticus
Methyldopa
MOA
- alpha-2 agonist (vasomotor center of medulla)
USE
- tx moderate HTN
SIDE FX: (+) Coombs’ test
OTHER: good for renal disease (no decrease in renal perfusion)
Phenoxybenzamine
MOA
- irreversible alpha antagonist (more 1 than 2) -> decr BP
USE
- tx pheochromocytoma (pre-surg or chronic tx for non-resectable)
SIDE FX
OTHER: phentolamine: short acting, reversible alpha antagonist -> dx pheo (larger than expected decr in in BP upon administration)
Prazosin
and other "-osin" drugs MOA - selective alpha-1 antagonist -> periph vasc relax -> decr BP - decr prostatic and bladder neck contraction -> improved urinary flow in BPH USE - tx HTN - tx benign prostatic hypertrophy (BPH) SIDE FX: first dose syncope OTHER
Propranolol
MOA
- beta-1 and -2 antagonist -> HR and contractility decr -> decr CO -> reflex peripheral vasoconstriction -> overall decr BP
- bronchoconstriction
USE
- tx cardiovascular (HTN, CAD)
- tx tachycardia assoc w/ hyperthyroid
- tx chronic migraines (causes cerebral vasodilation)
SIDE FX: bronchoconstriction, fasting hypoglycemia (beta-2 block decr glycogenolysis)
OTHER: pindolol, timolol, carvedilol
Metoprolol
MOA
- selective beta-1 antagonist -> decr HR and contractility -> decr CO
USE
- tx HTN, CAD (esp in pt with diabetes)
- tx wide angle glaucoma (reduce aq humor production - betaxolol)
SIDE FX
OTHER: esmolol, acebutolol
