Flashcards in Adrenergic Agonists Deck (35):
Epinephrine at low doses activates what receptors?
B1 and B2. Causes increased HR ad CO, vasodilation. Increased systolic BP and decreased diastolic BP. Bronchodilation.
Epinephrine at high doses activates what receptors?
A1, A2, B1, B2. Net effect increase HR and CO, increase systolic and diastolic BP. Increase MAP and TPR from A1/A2 activation of vasoconstriction.
Arrhythmias, cerebral hemorrhage, pulmonary edema, anxiety
Norepinephrine physiological effects
Activates A1, A2, B1. Increase in CO due to increased contractility (B1). Increase in MAP (systolic and diastolic) due to A1 activation. Decrease in HR as a baroreceptor reflex response.
Bronchospasm, anaphylaxis, cardiac arrest
Dopamine physiological effects at low doses?
Activate D1 and B1 receptors. Vasodilation in renal and splanchnic circulations (decrease in TPR due to D1 activation). Increase in HR and CO due to B1 activation.
Dopamine physiological effects at high doses?
Activates A1, A2, B1 receptors. Overall increase in MAP, TPR, and CO.
Dopamine toxicity at low and high doses?
Low dose toxicity: hypotension.
High dose toxicity: ischemia
Isopreterenol physiological effects?
Nonselective Beta agonist. Activate B1 receptors to increase HR, CO, systolic BP. Activate B2 to cause vasodilation, decrease in TPR. Bronchodilation caused by B2 activation.
Bradycardia or heart block when TPR is already too high
Angina with arrhythmias
Dobutamine physiological effects
Selective B1 agonist. Increase HR and increase CO.
Short term Rx for cardiogenic shock or CHF
Hypotension (excess Dobutamine will begin to activate B2 receptors. Arrhythmias.
Terbutaline and Albuterol Physiological effects
Selective B2 agonists. Bronchodilation and uterine relaxation.
Terbutaline and Albuterol Indications
Bronchospasm and COPD
Terbutaline and Albuterol Toxicity
Phenylephrine Physiological effects
Selective A1 agonist. Vasoconstriction (A1). Decrease in HR (baroreceptor reflex). Pupillary dilation (A1 activation- mydriatic agent). Decrease bronchiole and sinus secretions.
Hypotension during anasthesia
Mydriatic agent in ophthalmology
Clonidine Physiological Effects
Selective A2 agonist. Causes acute vasoconstriction (increase in BP), then long term decrease in BP due to negative feedback on presynaptic neurons in the CNS.
Hypertensive crisis if withdrawing from medication --> get excess sympathetic activation after A2 inhibition in the CNS.
Hypertension due to sympathetic activation
What are the indirect acting sympathomimetics? Basically, how do they function physiologically?
Either increase release of endogenous catecholamines or decrease reuptake of endogenous catecholamines.
Physiological effects of indirect acting sympathomimetics?
Increased TPR and MAP (A1, A2)
Positive inotropic and chronotropic effects (B1)
Toxicity of indirect acting sympathomimetics
Indications of indirect acting sympathomimetics
ADD, narcolepsy, nasal congestion
Contraindications of indirect acting sympathomimetics
Prior history of drug abuse
Patient has taken a monoamine oxidase inhibitor in the last two weeks.
Basic function amphetamine
Reverse monoamine reuptake transporter.
Basic functions Methylphenidate (Ritalin)
Dopamine reuptake inhibitor