Adrenergic Agonists & Antagonists Flashcards
Name the three direct-acting adrenergic agonists
Endogenous catecholamines
B-adrenergic agonists
A-adrenergic agonists
What are the three endogenous catecholamines?
Epinephrine
Norepinephrine
Dopamine
At low concentrations of epinephrine, which receptors are activated?
Beta 1 & 2
At high concentrations of epinephrine, which receptors are activated?
More alpha 1 & some beta 1
Which concentration of epinephrine can cause a baroreceptor reflex to occur?
High concentration
*Low does not increase MAP with B2 & B1 activation
What are the uses for epinephrine?
Cardiac arrest
Anaphylactic shock
Acute asthmatic attack
Which receptors does norepinephrine act on?
A1, A2, B1
*NOT B2
Can norepinephrine cause a baroreceptor reflex kick in?
Yes- no B2 action with norepinephrine
What are the uses for norepinephrine?
Treat shock
What are the control systems of the baroreceptor reflex?
Changes in vasculature lead to reading by baroreceptors on carotid sinus, this leads to change in heart contraction by sympathetic centers and change in heart rate by vagal centers
Which non-selective adrenergic agonist acts on Beta1 & Beta2 receptors and is used to stimulate the heart in patients with brachycardia or heart block?
Isoproterenol
Which selective adrenergic agonist acts on B1 and produces less increase in HR and less decrease in PVR than isopreternol?
Dobutamine
*also increases O2 consumption for stress test
Which selective adrenergic agonist acts on B2 receptors and is used in asthma attacks?
Albuterol
Which selective adrenergic agonist acts on A1 receptors and is used as a nasal decongestant or to produce mydriasis?
Phenylephrine
Which selective & partial adrenergic agonist acts on A2 receptors and inhibits the release of NE, reducing sympathetic outflow?
Clonidine
What are the two classes of indirect-acting adrenergic agonists?
Releasing agents & uptake inhibitors
Which releasing agent causes NE release, acts on A1 and B1 receptors and is used for ADHD and narcolepsy?
Amphetamine
Which releasing agent also causes NE release and is oxidized by MAO?
Tyramine
*if patient is taking MAO inhibitor (antidepressant), tyramine can cause vasopressor episodes
Which uptake inhibitor blocks monoamine reuptake resulting in potentiation and prolonging of central and peripheral actions?
Cocaine
What are the two mixed-acting adrenergic agonists that act by causing release of NE?
Ephedrine and pseudoephedrine
Which mixed-acting agonist is a poor substrate for COMT & MAO, having long duration, penetrates CNS, and is used as a pressor agent for spinal anesthesia?
Ephedrine
Which mixed-acting agonist is one of four ephedrine enantiomers and is commonly used in decongestant mixtures (sudafed)?
Pseudoephedrine
Name the two types of alpha & beta antagonists
Non-selective alpha or beta antagonists
A1 or B1 selective antagonists
Name the two types of non-selective alpha antagonists
Phenoxybenzamine
Phentolamine
Which non-selective alpha antagonist acts irreversibly on A1 & A2 receptors, has been found unsuccessful for hypertension cases, and is used prior to tumor removals for pheochromocytoma?
Phenoxybenzamine
Which non-selective alpha antagonist acts reversibly on A1 & A2 receptors, can be used to control hypertension in pheochromocytoma pre-ops & surgical removals, and can be used as an antidote for hypertension due to stimulate drug overdoses?
Phentolamine
Which selective alpha antagonist is specific for A1 receptors, is used for hypertension (not a DOC), and for symptom relief of benign prostatic hyperplasia?
Prazosin
Which non-selective beta antagonist acts on B1 & B2 receptors and cause respiratory crisis in COPD or asthma patients?
Propranolol
Which beta selective antagonist acts on B1 receptors and is used in diabetic hypertension patients?
Atenolol
Which partial beta antagonist competes with NE and is preferred in patients with diminished cardiac reserve or brachycardia?
Pindolol
What are adverse effects of beta blockers?
Bronchoconstriction (avoid with asthmatic patients)
Hypoglycemia (avoid in patients with insulin-dependent diabetes due to B2 inhibition of gluconeogenesis —> B1 blocker preferred)
CNS - sedation, dizziness, fatigue etc.