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104 Cards in this Set
- Front
- Back
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Name some sympathomimetics.
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1. Catecholamines
2. Synthetic catecholamines 3. Synthetic noncatecholamines |
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What effects do sympathomimetics have?
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They have effects similar to those produced by the SNS.
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What are some clinical uses of sympathomimetics?
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1. Increase myocardial contractility
2. Increase SBP 3. Sustain SBP during elimination of excess inhaled anesthetics 4. Sustain SBP during restoration of intravascular volume 5. Tx of bronchospasm 6. Management of anaphylaxis 7. Administration of local anesthetics |
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What is the disadvantage of sympathomimetics without beta-1 effects?
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1. Decrease in HR
2. Decrease in cardiac output |
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What are all sympathomimetics derived from?
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Beta-phenyethylamine
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Why does phenylephrine select alpha receptors?
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It lacks a hydroxyl group on carbon number 4.
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Why does isoproterenol select B1 and B2 receptors?
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It has an isopropyl group on the terminal amine.
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Why do albuterol, terbutaline, and metaproterenol select more of the B2 receptors?
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They have a hydroxyl group in 3,5 carbons of the benzene ring.
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How do sympathomimetics activate adrenoreceptors?
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1. Directly
2. Indirectly |
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What are the steps involved with the mechanism of action of sympathomimetics?
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1. The sympathomimetic binds to cell surface receptors
2. A conformational change occurs and G protein is activated 3. G protein encounters the effector protein 4. The effector protein is an intracellular enzyme or an ion channel 5. Concentration of an intracellular 2nd messenger changes or cell membrane potential changes |
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What are some factors of pharmacological effects of sympathomimetics?
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1. Density of alpha and beta receptors in the tissues
2. The anatomic distribution of A&B receptors |
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What is the relationship between sympathomimetics and receptors?
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There is an inverse relationship between the concentration of sympathomimetics and the numbers of receptors.
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What is the direct mode of action of sympathomimetics?
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Adrenergic receptors are activated directly.
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What is the indirect mode of action of sympathomimetics?
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1. Receptors are activated by the release of the endogenous norepi from post ganglionic sympathetic nerve endings.
2. Depletion of this neurotransmitter blunts the pharmacologic effects. |
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How are enzymes and catecholamines metabolized?
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MAO and COMT
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How are catecholamines terminated?
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By uptake back into post ganglionic sympathetic nerve endings.
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What is the role of the lungs with catecholamines?
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They are biochemical filters for central venous blood of endogenous catecholamines during pulmonary transit.
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How are noncatecholamines metabolized?
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MAO
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How is ephedrine excreted?
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Unchanged in urine
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List the natural catecholamines.
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1. Epinephrine
2. Norepineprhine 2. Dopamine |
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Where is epi released from?
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The adrenal medulla.
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What effect does epi have on receptors?
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1. A1=A2
2. B1=B2 |
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What are some clinical uses of epi?
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1. Added to local anesthetics
2. Tx for life-threatening allergic reactions 3. CPR drug 4. Infusion to increase myocardial contractility |
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How does epi affect the HR?
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It accelerates the rate of spontaneous phase 4 depolarization.
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How does epi affect cardiac output?
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1. Increases HR
2. Increases myocardial contractility 3. Increases venous return 4. Decreases SVR |
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How does epi affect renal blood flow?
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It decreases renal flow.
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How does epi affect B2 receptors?
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Bronchi are relaxed by increasing intracellular cAMP.
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What are the metabolic effects of epi?
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B1 effects increases:
1. glycogenolysis 2. adipose tissue lipolysis |
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What are some general side effects of epi?
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1. Mydriasis
2. Relaxation of GI smooth muscle 3. Increases activity of factor V (hypercoagulable state) |
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Where is norepi released from?
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Postganglionic sympathetic nerve endings.
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What receptors does norepi have an effect on?
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1. A1=A2
2. B1>B2 |
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What is norepi's effect on A1 receptors?
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Arterial and venous vasoconstriction.
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What are some cardiovascular effects of norepi?
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1. Intense vasoconstriction
2. Increased SBP 3. Increased diastolic BP 4. Increased MAP 5. Decreased HR (due to increased MAP) 6. Decreased cardiac output 7. Decreased tissue blood flow leading to metabolic acidosis |
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What is the immediate precursor of norepi?
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Dopamine
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What functions does Dopamine regulate?
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1. Cardiac
2. Vascular 3. Endocrine |
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What receptors does Dopamine effect?
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1. D1=D2
2. B>A |
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Where are D1 receptors located?
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Postsynaptic location.
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What are the effects of D1 receptors?
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Vasodilation of:
1. Renal mesenteric vessels 2. Coronary vessels 3. Cerebral vessels |
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Where are D2 receptors located?
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Presynaptic location
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What are the effects of D2 receptors?
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1. Inhibits adenylate cyclase activity
2. Inhibits release of norepi |
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What should be used to dilute catecholamines?
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D5W
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What should be used to tx local infiltration of dopamine?
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Phentolamine
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What effect does dopamine have on insulin?
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It induces it, causing hyperglycemia.
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What are the clinical uses of dopamine?
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1. Increases cardiac output
2. Increases myocardial contractility 3. Increases renal blood flow 4. Increases glomular filtration rate 5. Increases sodium excretion 6. Increases urine output |
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What is the renal dose of dopamine?
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1-3 mcg/kg/min IV
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What are the risks of renal dose dopamine?
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1. Tachycardia
2. Cardiac dysrhythmias 3. MI 4. Decreased ventilatory response to hypoxia 5. Increased pulmonary shunting 6. Development of mesenteric ischemia |
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What are the cardiac side effects of dopamine?
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1. Increased HR
2. Increased SBP 3. Increased SVR 4. Uncompensated increase in splanchnic oxygen requirements |
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What is the cardiac effect of dopamine and dobutamine give together?
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It has the same effect as IABP:
1. Increased coronary perfusion 2. Increased cardiac output 3. Decreased afterload |
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What are the ventilatory effects of dopamine?
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Depressed response to arterial hypoxemia.
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What effect does dopamine have on the eyes?
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Increased intraocular pressure
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List the synthetic catecholamines.
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1. Isoproterenol
2. Dobutamine |
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What is the most potent B1 and B2 agonist?
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Isoproterenol
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What effect does isoproterenol have on receptors?
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B1=B2
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How is isoproterenol metabolized?
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1. In the liver by COMT
2. Minimal uptake by postganglionic nerve endings |
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What drug is known as the "chemical pacemaker"?
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Isoproterenol
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What are the clinical uses of isoproterenol?
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1. Increases HR for pts receiving temporary or permanent pacers
2. Bronchodilator |
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What are the B1 effects of isoproterenol on the cardiovascular system?
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1. Increased HR
2. Increased myocardial contractility 3. Increased cardiac automaticity |
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What are the B2 effects of isoproterenol on the cardiovascular system?
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1. Decreased SVR
2. Increased cardiac output 3. Increased SBP 4. Decreased MAP |
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What are some undesired cardiac side effects of isoproterenol?
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Increased HR and myocardial contractility lead to:
1. Decreased coronary blood flow 2. Increased oxygen requirements |
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What receptors does dobutamine effect?
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B1>B2
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What effect do dobutamine isomers have on receptors?
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Agonist and antagonist effects on A1 receptors.
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What are clinical uses of dobutamine?
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1. Tx of CHF
a. Increases cardiac ouput b. No change in SVR 2. Decreases afterload in combo with dopamine |
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How is dobutamine used to treat increased PAP.
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Tx for increased PAP after MVR:
1. Increases cardiac output 2. Decreases SVR 3. Decreases PVR |
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How does dobutamine effect coronary arteries?
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It vasodilates coronary arteries.
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How might dobutamine affect a pt with a hx of Afib?
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It could create an excessive increase in HR.
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List the synthetic noncatecholamines.
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1. Mephentermine
2. Metaraminol 3. Methoxamine 4. Amphetamine 5. Phenylephrine 6. Ephedrine |
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What receptors does ephedrine effect?
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1. A1=A2
2. B1=B2 |
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How is ephedrine metabolized?
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1. MAO
2. Conjunction at liver |
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What are clinical uses of ephedrine?
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1. Increases SBP for SNS blockage produced by regional anesthesia or inhaled agents.
2. Tx for hypertension in parturients. 3. Anitemetic |
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What are the cardiovascular effects of ephedrine?
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1. Increased SBP
2. Increased diastolic BP 3. Increased HR 4. Increased cardiac output 5. Increased coronary blood flow 6. Increased skeletal blood flow 7. Increased myocardial contractility |
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Does tachyphylaxis occur with ephedrine?
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Yes. Receptor sites still are still occupied by ephedrine or there is a depletion of norepi stores.
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What receptors do amphetamines effect?
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A=B
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List amphetamines.
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1. Dextroamphetamine
2. Methamphetamine |
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What are side effects of amphetamines?
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Release of norepi in CNS causes:
1. Significant CNS stimulation 2. Appetite suppression |
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What effect does chronic administration of amphetamines have on anesthesia?
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It decreases CNS stores of catecholamines, thereby reducing anesthetic requirements.
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How do you treat amphetamine overdose?
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Acidification of urine.
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How does ephedrine act on receptors?
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Directly and indirectly.
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What receptors does phenylephrine effect?
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A1>A2>>>B
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How does phenylephrine affect A1 receptors?
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1. Direct effect
2. Small release of norepi |
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What are clinical uses of phenylephrine?
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1. Tx of hypotension due to regional or inhaled anesthetics
2. CAD and aortic stenosis 3. Carotid endarterectomy 4. Nasal decongestant 5. Prolonged use of local anesthetics |
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Why is phenylephrine useful in the tx of CAD and aortic stenosis?
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It increases coronary perfusion without a chronotropic effect.
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What are cardiovascular side effects of phenylephrine?
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1. With rapid IV injection:
a. Increased SBP b. Decreased CO 2. Impairment of left ventricular function in CAD |
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What are metabolic side effects of phenylephrine?
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Infusion during acute potassium loading interferes with movement of potassium across cell membranes into cells (hyperkalemia).
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What could happen if pt receives phenylephrine while on beta blockers?
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1. Pulmonary edema
2. Cardiovascular collapse |
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What is the tx for pulmonary edema caused by phenylephrine overdose?
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1. Nitroprusside
2. Nitroglycerine |
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What is the tx for cardiovascular collapse caused by phenylephrine overdose?
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Glucagon 1-5 mg IV
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Is morbidity and mortality improved if dopamine is used over dobutamine for renal perfusion?
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No
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In general, why is isoproterenol used?
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To treat complete heart block.
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In general, why is dobutamine used?
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To increase myocardial contractility, especially if HR and SVR are increased.
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In general, why is epi used?
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1. To prolong action of local anesthetic when added to LA solutions
2. Tx of life threatening allergic reactions 3. CPR 4. To increased myocardial contractility |
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In general, why is ephedrine used?
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To treat hypotension in association with:
1. Spinal or epidural in parturients 2. Overdose of inhaled or injected anesthetics 3. Hypovolemia |
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In general, why is phenylephrine used?
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1. Tx of hypotension
2. Tx of supraventricular cardiac tachydysrhythmias associated with hypotension 3. Topical nasal decongestant or mydriatic |
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List the tissues A1 receptors affect and the resulting agonist effect.
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1. Most vascular smooth muscle - contraction
2. Pupillary dilator muscle - dilation of pupil 3. Pilomotor smooth muscle - erects hair 4. Prostate - Contraction 5. Heart - Increases force of contraction |
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List the tissues A2 receptors affect and the resulting agonist effect.
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1. Postsynaptic CNS adrenoreceptors - Multiple effects
2. Platelets - Aggregation 3. Adrenergic and cholinergic nerve terminals - Inhibition of transmitter release 4. Some vascular smooth muscle - Contraction 5. Fat Cells - Inhibition of lipolysis |
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List the tissues B1 receptors affect and the resulting agonist effect.
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Heart - Increases force and rate of contraction
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List the tissue B2 receptors affect and the resulting agonist effect.
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1. Respiratory, uterine, and vascular smooth muscle - Promotes smooth muscle relaxation
2. Skeletal muscle - Promotes potassium uptake 3. Human liver - Activates glycogenolysis |
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List the tissues B3 receptors affect and the resulting agonist effect.
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Fat cells - Activates lipolysis
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List the tissues D1 receptors affect and the resulting agonist effect.
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Smooth muscle - Dilates renal blood vessels
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List the tissues D2 receptors affect and the resulting agonist effect.
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Nerve endings - Modulates transmitter release
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Where in the cardiovascular system are B2 receptors predominantly located?
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In the smooth muscle of the vasculature of skeletal muscle.
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List the alpha agonists.
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1. Phenylephrine
2. Clonidine |
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List the mixed alpha and beta agonists.
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1. Norepi
2. Epi |
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List the beta agonists.
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1 Dobutamine
2. Isoproterenol 3. Terbutaline 4. Albuterol |
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List the dopamine agonists.
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1. Dopamine
2. Fenaldopam |
