Autonomics: Adrenergic Agonists and Antagonists Flashcards
Alpha 1
Gq Transmembrane - Phospholipase C to increase DAG and IP3 to increase intracellular calcium.
Contraction of vascular smooth muscle, contracts pupil muscle causing dilation, erects hair, contracts prostate, increases force of contraction on heart, increases glycogenolysis, decreases renin release.
Alpha 2
Gi - decrease adenylyl cyclase to decrease cAMP
multiple effects on CNS, causes platelet aggregation, inhibition of neurotransmitter release in presynaptic nerve terminals, contracture of vascular smooth muscle, inhibition of lipolysis in fat cells and decreased insulin secretion.
Beta 1
Gs Increase adenylyl cyclase to increase cAMP
HEART, increase HR at SA node, and conduction velocity at AV node, increase force of contracture, conduction velocity, cardiac output, increases renin release.
Beta 2
Gs Increase adenylyl cyclase to increase cAMP
Vasodilation of blood vessels, stimulated glycogenolysis in muscles to promote contractility (Tremor), bronchiodilation, increase in glucagon secretion, and relaxation of uterus
Beta 3
Gs Increase adenylyl cyclase to increase cAMP
activates lipolysis, relaxes detrusor muscle
Dopamine 1
Gs Increase adenylyl cyclase to increase cAMP
Vasodilation in renal, mesenteric and coronary vasculature, increases GFR, renal blood flow and Na secretion.
Norepinephrine (levophed)
alpha -1 alpha -1 beta -1 beta -3
Heart: increases pacemaker, conduction, force of contraction, decreases HR by vagal response.
Arteries: Vasoconstriction
Veins: venoconstriction
Decrease in HR, MPB slightly increased, net peripheral resistance increased. Used to maintain BP in shock and hypotension
Adverse: tissue necrosis and sloughing in extravasation. anxiety, hyperglycemia, arrhythmias, and cerebral hemorrhage.
Epinephrine
alphas and betas
Heart: increase pacemaker, conduction, force of contraction, and rate.
Arteries: vasoconstriction except in most arterial beds - vasodilation in skeletal muscle.
Lungs: bronchodilation, decongestion
HR increase, MBP remains unchanged, decrease in net peripheral resistance. Used for anaphylactic shock - bronchodilator, maintain heart, beta attenuates histamine release.
Adverse: restlessness, tremor, palpitations, cerebral hemorrhage, tachycardia, arrhythmias, hyperglycemia.
Isoproterenol
betas
Heart: increase pacemaker, conduction, force and rate of contraction.
Vasodilation in arteries, bronchodilation in lungs
HR increases, MBP decrease, Net resistance decreases. Used as bronchodilator and emergency stimulant.
Adverse: Palpitation, headache, flushed skin, tachycardia, cardiac ischemia and arrhythmias.
Dopamine
dopamine-1, beta-1, alpha-1
Effects highly dependent on dose used.
Increased heart output, blood pressure, improved renal and intestinal perfusion.
HR increases, MBP increase, net resistance decrease. Used for short term cardiovascular support. Used when BP in low and able to administer drug through IV. Used during congestive heart failure, and reserves the kidneys in periods of shock.
Adverse: tachycardia, excessive vasoconstriction, can produce ischemic necrosis and sloughing, headaches, nausea, vomiting.
Dobutamine
beta-1, beta-2 > alpha-1
Increases output and stroke volume without similar increase in rate of heart, no real change in vascular resistance.
Mild alpha-1 agonist (racemic mixture).
Used for short-treatment of cardiac decompensation.
Adverse: Blood pressure and heart rate increase during rapid infusion, hypertensive patients may experience exaggerated pressor response, arrhythmias, increase oxygen demand of tissues.
Beta -2 Selective
Active bronchodilators, delay premature labor (tocolysis), minimize beta-1 stimulation on heart, vasodilators.
Increase usefulness in treatment of asthma, bronchospasm, and emphysema.
Asthma: inhalation forms are preferred, oral routes accepted. Arterial oxygen tension may fall during treatment due to vasodilation of pulmonary beds.
Adverse: tremor, underlying increase risk of cardiovascular disease, tachycardia (adverse beta-1 stimulation).
Albuterol
Short-acting beta-2 selective
Ipratropium
Short-acting beta-2 selective
Levalbuterol
short-acting beta-2 selective
Metaproterenol
short-acting beta-2 selective
Arformoterol
long-acting beta-2 selective
Fromoterol
long-acting beta-2 selective
Indacaterol
long-acting beta-2 selective
Salmeterol
long-acting beta-2 selective
Not recommended for acute treatment of asthma due to slow onset
Terbutaline
long acting beta-2 selective
Subcutaneous or intravenous for emergency asthma attack.
Mirabegron
Beta-3 selective agent
Relaxes detrusor smooth muscle of urinary bladder to increase capacity. Orally active with 50hr half life (hepatic biotransformation).
Contraindications: Bladder or urinary obstruction, pregnancy or breast feeding, renal or hepatic dysfunction, MAO-inhibitor therapy, hypertension.
Adverse effects: hypertension, sinus tachycardia or heart, gastric distress, increased UTI, headache, increased risk of respiratory infections.
Oxymetazoline
Alpha-1 selective agent
Therapeutic: Nasal decongestant, mydriasis, maintenance of blood pressure through surgery (vasoconstriction)