Term
| what is the mechanism for drugs acting at alpha receptors? |
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Definition
| the phosphatidylinositol second messenger system (IP turnover) |
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Term
| what are the specific alpha agonists? |
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Definition
| norepinephrine, phenylephrine, methoxamine, metaraminol, phenylpropanolamine, and pseudoephedrine |
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Term
| what is the effect of norepinephrine administration? |
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Definition
| norepinephrine is a pressor, meaning it will vasoconstrict, increasing TPR, which will increase mean BP (systolic and diatolic). HR will be unchanged or drop slightly. |
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Term
| what is the purpose of norepinephrine administration? |
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Definition
| tx of hypotensive states (except those resultant from low blood volume) |
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Term
| what is the effect of phenylephrine administration? |
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Definition
| it is a pressor (*even though OTC, can increase BP), decongestant, and mydriatic |
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Term
| what is phenylephrine ususally used to treat? |
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Definition
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Term
| what is the effect of methoxamine administration? |
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Definition
| methoxamine is an IV pressor |
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Term
| what is the effect of metaraminol administration? |
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Definition
| it is a IV pressor which acts at alpha 1. it also stimulates the release of endogenous NE. |
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Term
| what was phenylpropanolamine? |
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Definition
| a decongestant/anorectic that has since been removed from the market, b/c of increased stroke/MI risk. just because something has been around for a long time, doesn’t meant it’s 100% safe. |
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Term
| what is the effect and typical purpose of pseudoephedrine? |
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Definition
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Term
| what are the ADRs fro all alpha agonists? |
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Definition
| anxiety, resp difficulty, forceful heart beat, headache, HTN w/violent headache, infiltration necrosis with IV (local alpha receptors causing overconstriction of blood vessels), rebound nasal congestion (exact opposite effect after a certain amount of accumululation or exposure) |
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Term
| what is the one drug that has specific alpha 2 specificity? what is the effect of its administration? |
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Definition
| clonidine, which causes hypotension, sedation, bradycardia, and decreased central outflow of impulses in the sympathetic nervous system |
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Term
| where does clonidine work? |
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Definition
| not at the adrenergic terminal, but in the nucleus tractus solitarius in the brain stem -> "big heart control center" in the brain stem, drops BP |
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Term
| what is the mechanism for drugs acting at beta receptors? |
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Definition
| the adenylyl cyclase second messenger system |
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Term
| what are the specific beta (1+2) agonists? |
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Definition
| isoproterenol and dobutamine |
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Term
| what is the effect of isoproterenol administration? |
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Definition
| smooth muscle relaxation (bronchioles, intestinal tract), skeletal muscle vasodilation (TPR drop, *concurrent diastolic drop), increased cardiac output (positive inotropic, chronotropic, and rise in systolic pressure), glycogenolysis and hyperlipidemia, and myometrial relaxation |
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Term
| what is the effect of dobutamine administration? |
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Definition
| increased CO, SV w/out marked increase in HR. minor alterations in BP/TPR and a half-life of 2 min (is both alpha and beta stimulatory, but beta activity predominates) |
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Term
| what is dobutamine administered for? |
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Definition
| short term treatment of cardiac decompensation following cardiac sx, congestive heart failure, and acute MI via continous IV |
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Term
| what drug do we need to know that is specific for beta2 receptors? what is it used for? |
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Definition
| terbutaline, which is used typically for asthma tx or bronchospasm (for bronchodilatory effects) |
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Term
| what are ADRs for beta agonists? |
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Definition
systemic beta1: tachycardia
beta2: skeletal muscle tremors (possibly due to dilation) |
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Term
| what are the specific agonists? |
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Definition
| epinephrine, dopamine, and ephedrine |
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Term
| what is administration of epinephrine used for? is it dose dependent? |
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Definition
| epinephrine is used to relieve respiratory distress due to bronchospasm (low dose, beta receptors) and to prolong the effect of local anesthetics (high dose, wider distribution) |
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Term
| what is administration of dopamine used for? is it dose dependent? |
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Definition
| dopamine in low doses activates the D1 (dopamine) receptor, causing vasodilation of renal, mesenteric and coronary beds. in moderate doses, dopamine has a positive inotropic effect on the myocardium via the beta1 receptor. dopamine in high doses causes release of NE from nerve terminals (alpha1), resulting in vasoconstriction. |
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Term
| what is administration of ephedrine used for? |
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Definition
| ephedrine has alpha action; increased HR, CO, TPR, and BP and beta action; bronchodilation. it also enhances the release of NE. ephedrine is used for tx of asthma and nasal congestion |
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