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MedSurg I HTN Meds PRELOAD & AFTERLOAD

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olanjones's version from 2016-12-08 00:56

Drug Classes Affecting Preload

Question Answer Column 3
ThiazidesInhibit NaCl resorption increase excretion Na & ClDecrease BP over 2-4 weeks
Loop DiureticsInhibit NaCl resorption increase excretion Na & ClUsed more for CHF or to reduce edema (less for HTN control)
K+ sparing DiureticsReduce K & Na exchangeWatch K+ intake (risk for hyperkalemia)
Aldosterone Receptor blockersInhibit retention of Na & excretion of K+Watch K+ intake (risk for hyperkalemia); Cautious use with ACE-I or ARBs
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Drug Classes Affecting Afterload

Question Answer Column 3
Central acting α-Adrenergic AntagonistsReduce peripheral sympathetic tone, produce vasodilationDo not stop abruptly, must taper off or risk rebound HTN
Peripheral-Acting α-Adrenergic Antagonists (-zosin)Prevents release of norepi –> peripheral vasodilationHypotensive effect delayed 2-3 days & lasts 7-10 days after withdrawal
α1-Adrenergic BlockersBlock α1 effects – peripheral vasodilationUse HS dosing to reduce hypotension
Direct Vasodilatorscause vasodilation*Nitroglycerine also relaxes venous smooth muscle, reducing preload
Ganglionic BlockersInterrupts adrenergic control of arteries, causes vasodilationIV for initial BP control in dissecting AA
CCB Non-DihydropyridinesInhibit Ca++ across membrane, cause vasodilation, Decrease heart rate and slow AV conductionAvoid grapefruit juice- may increase effect
CCB Dihydropyridines (-dipine)Cause vascular smooth muscle relaxation, vasodilationmore potent for peripheral vasodilation
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Drugs Affecting Preload & Afterload

Question Answer Column 3
β-Adrenergic Blockers Cardioselective (β1) (-olol)Reduce vasoconstriction, Decrease renin secretionWatch in DM may mask hypoglycemic symptoms
β-Adrenergic Blockers Nonselective (β1& β2) Reduce vasoconstriction, Decrease renin secretionRisk for bronchospasm
Mixed α- and β-Blockers (-alol)same as α- and β-BlockersIV form used in HTN crisis – keep supine
Angiotensin-Converting Enzyme Inhibitors (-pril)Inhibit Angiotensin II mediated vasoconstriction & subsequent aldosterone & ADH productionMay be used with diuretics - but not w/ k-sparing
Angiotensin II Receptor Blockers (-sartan)Prevent action of A-II, cause vasodilation and increase Na excretionFull effect may not be seen for 3-6 weeks
Renin InhibitorsReduce conversion of angiotensinogen to angiotensin IMay cause angioedema
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