Vasopressors Flashcards
phenylephrine
Noncatecholamine with mainly direct alpha1 agonist activity –> mainly causes peripheral vasoconstriction; tachyphylaxis
Ephedrine
Noncatecholamine with direct an indirect effects that increase BP, HR, contractility, and CO, also bronchodilates
What are alpha 1 receptors?
Postsynaptic receptors that when activated increase intracellular calcium and leads to muscle contraction
Alpha 1 effects
Mydriasis, bronchoconstriction, vasoconstriction, uterine contraction, contraction of sphincters, inhibits insulin secretion and lipolysis
What are alpha 2 receptors?
Presynaptic receptors that when activated inhibit adenylate cyclase that decreases entry of calcium and exocytosis of norepinephrine from vesicles
Alpha 2 effects
Vasoconstriction and negative norepinephrine feedback loop; CNS receptors cause sedation and decreased sympathetic outflow
What are beta 1 receptors?
Postsynaptic receptors located on the heart
Beta 1 effects
Positive chronotrope (HR), dromotrope (conduction), inotrope (contractility)
What are beta 2 receptors?
Postsynaptic receptors found in smooth muscle and glands
Beta 2 effects
Relaxes smooth muscle - bronchodilation, vasodilation, relaxation of uterus (tocolysis), bladder, and gut, stimulates glycogenolysis, gluconeogenesis, and insulin release; activates sodium/potassium pump (K into cell)
What is methyldopa? Effects?
Alpha 2 agonist that is converted to alpha methylnorepinephrine and alpha methylepinephrine, and caused decreased norepinephrine release and sympathetic tone
What is clonidine? Effects?
Alpha 2 agonist that is a sedative, anxiolytic, analgesic, antihypertensive, and negative chronotrope, bradycardia, respiratory depression
What is dexmedetomidine? Effects?
Alpha 2 agonist that causes sedation, analgesia, and sympatholytic without significant respiratory depression
What happens with rapid dexmedetomidine administration?
HTN but ongoing therapy can cause hypotension and bradycardia
Epinephrine beta 1
Direct beta 1 stimulation causes increase CO and myocardial demand by increasing contractility and HR
Epinephrine alpha 1
Decreases splanchnic and renal blood flow, increase coronary and cerebral perfusion pressure
Epinephrine beta 2
Relaxes bronchial smooth muscle, vasodilation in skeletal muscle may decrease diastolic BP
Epinephrine 1:1,000
1 mg per ml
Epinephrine 1:10,000
100 mcg/ml (0.1 mg/ml)
Epinephrine 1:100,000
10 mcg/ml (0.01 mg/ml)
Epinephrine 1:200,000
5 mcg/ml (0.005 mg/ml)
What is norepinephrine?
Direct alpha 1 and beta 1 stimulation
What is dobutamine? Effects?
Relatively selective beta 1 agonist increases CO and contractility, less increase in HR , while beta 2 prevents increased BP –> LV filling pressure decreases and coronary blood flow increases
Which patient is ideal for dobutamine?
Patients with CAD and CHF especially if peripheral vascular resistance and HR are high
