Term
| digitalis glycosides - digoxin (Lanoxin) |
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Definition
| used in treatment of CHF to: 1) increase myocardial contraction & 2) decrease heart rate; indirect positive effect: increased urine output in pts w/ CHF |
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Term
| digitalis glycosides - digoxin (Lanoxin) - MoA: Increased Myocardial Contraction |
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Definition
| most important of drug in treating CHF; directly increases intrinsic force of myocardial contraction --> increases CO, reverses SNS-induced reflex tachycardia, & increases excretion of accumulated salt & water; Mechanism: directly inhibits cell membrane bound Na/K-ATPase --> reduces Na transport out of cell --> increased intracellular Na conc. --> reduces Ca transport out of cell --> increases intracellular free Ca --> increased myocardial contractility |
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Term
| digitalis glycosides - digoxin (Lanoxin) - MoA: Decreases Heart Rate |
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Definition
| in addition to reversal of SNS-induced reflex tachycardia, "Vagal Slowing" occurs: central vagal stimulation + stimulation of receptors at autonomic ganglia & cardiac sites & possibly carotid baroreceptors; "Extravagal slowing": higher doses, lengthening of effective refractory period & decreased conduction velocity of electrical activity in AV-node; these drugs ARE NOT recommended to slow heart in NORMAL sinus tachycardia if there is no accompanying CHF |
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Term
| PK properties of digiToxin |
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Definition
| 95% absorbed from GI; 97% protein bound; onset of action: 1-2 hrs; T1/2: 5-7 days; TI: 14-26 ng/cc; Toxic levels: >34 ng/cc; Mode of inactivation: hepatic |
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Term
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Definition
| 60-80% absorbed in GI; 20% protein bound; Onset: 0.2-0.5 hrs; T1/2: 1.5-2 days; TI: 0.8-1.6 ng/cc; Toxic levels: >2.5 ng/cc; Mode of Inactivation: renal |
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Term
| Drug Interactions with Digitalis |
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Definition
| levels increase when taking phenylbutazone (plasma protein binding) & quinidine (displaces drug at binding sites); phenobarbital & phenytoin decrease plasma levels & T1/2 by inducing hepatic enzyme metabolism; bioavailability reduced by antacids, sulfasalazine, & bile acid-binding resins (cholestyramine) |
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Term
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Definition
1) administer "first day" loading dose followed by daily maintenance dose;
2) give ONLY a maintenance dose each day, longer period of time for pt to become fully digitalized |
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Term
| loading "digitalizing" dose |
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Definition
| amount of digitalis glycoside necessary to rapidly bring body stores to an effective level on 1st day |
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Term
| usual maintenance dose of digitalis |
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Definition
| amount of digitalis glycoside lost from body in 24 hrs which must be replaced once daily |
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Term
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Definition
| GI: anorexia, nausea, vomiting; Cardiac: all known arrhythmias, abnormal bradycardia, paroxysmal atrial tachycardias, ventricular tachycardias & fibrillations (SERIOUS & FATAL); CNS: mental disorientation, delirium; Blurred vision, white borders or halos on dark objects; Ca & drug are synergistic: rise in Ca --> arrhythmias in drugged person; K & drug are antagonists: in drug intoxication, increasing K alleviates toxic symptoms & lowering K aggravates symptoms; Acid-base imbalance & low Mg INCREASE toxicity |
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Term
| Treatment of Digitalis Toxicity |
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Definition
| 1) plasma drug levels helpful; 2) D/C drug or decrease dose; 3) D/C or decrease diuretics if K is too low; 4) Administer oral or infusion IV KCl if above measures don't work; To counteract arrhythmias: use lidocaine or propanolol; Tx life-threatening toxicity + overdose with severe hyperkalemia with digoxin immune fab (DIGIBIND) |
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Term
| digoxin immune fab (DIGIBIND) |
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Definition
| antigen binding fragments that bind to molecules of digoxin or digitoxin resulting in Fab-Fragment-digitalis complex that is excreted in urine; used for life-threatening digitalis glycoside toxicity + overdose characterized by severe hyperkalemia |
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Term
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Definition
| synthetic beta-1-adrenergic agonist; IV only to treat severe, refractory CHF; 1) increases CO by increased ventricular beta-1-receptor action (positive inotropic effect), 2) causes tachycardia & increase in cardiac oxygen demand & arrhythmia; tolerance can develop |
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Term
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Definition
| endogenous catecholamine; used only IV to treat severe, refractory CHF; exerts positive inotropic effect by direct activation of heart beta-1 receptors --> increases HR & oxygen demand; at low to intermediate doses, it increases RENAL blood flow due to activation of DA receptors --> enhances Na & H2O excretion; SEs: arrhythmia, tachycardia, increased risk of ischemic heart dx; tolerance can develop |
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Term
| inamrinone & milrinone [Primacor] |
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Definition
| non-glycoside, non-catecholamine postive inotropic drugs; phosphodiesterase inhibitors --> increases ventricular cell cAMP --> increses free Ca availability --> increased contractility during systole, also improves diastolic relaxation by stimulation more SR Ca uptake during diastole; used IV for severe, refractory CHF after tolerance from catecholamines develops; also has peripheral vasodilator effects; Toxicities: thrombocytopenia (I only), hazardous in pts w/ ischemic heart disease |
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Term
| ACE Inhibitors - captopril (Capoten), enalapril (Vasotec), fosinopril (Monopril), quinapril (Accupril) |
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Definition
| inhibits angiotensin converting enzyme --> decreases angiotensin II formation --> inhibits vasoconstriction & release of aldosterone --> decreases preload & afterload --> indirectly increases CO & exercise capacity & decreases pulmonary & peripheral congestion; corrects high endogenous aldosterone-related & diuretic-induced hypOkalemia; some are prodrugs activated in liver; SEs: non-productive cough, hyperkalemia, hypotension, angioedema, avoid during pregnancy |
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Term
| diuretics - thiazides (HCTZ), loop (furosemide), K-sparing (spiranolactone, eplerenone) |
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Definition
| drugs the reduce extracellular fluid volume, reduce preload, relieve pulmonary congestion, & reduce peripheral edema |
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Term
| ARBs - losartan (Cozaar), valsartan (Diovan), candesartan (Atacand) |
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Definition
| competitive antagonists of A-II that decreases vasoconstriction & aldosterone levels; DO NOT cause as much cough as ACE-Is; may contribute better inhibition of A-II contribution to cardiac hypertrophy than ACE-Is |
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Term
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Definition
| dilates arterial resistance vessels by inhibiting vasoconstriction produced by NE or A-II or vasopression --> reduces impedance (afterload) to left ventricular ejection --> beneficial hemodynamic effects in CHF; some can decrease preload or ventricular filling pressure by increasing venous capacitance through venodilation |
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Term
| nitroglycerin [Minitran], isosorbide dinitrate [Isosordil] |
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Definition
| direct vasodilators that primarily reduce preload; tolerance can occur with long-term use |
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Term
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Definition
| direct vasodilator that primarily reduces afterload |
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Term
| nitroprusside [Nitropress] |
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Definition
| direct vasodilator that primarily reduces both preload & afterload; given IV only |
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Term
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Definition
| direct vasodilator that decreases both arterial & venous smooth muscle tone by increasing intracellular cGMP; also has diuretic action due to its natural natriuretic capability; given IV only |
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Term
| beta-blockers - bisoprolol [Zebeta], metoprolol [Lopressor, Toprol XL], carvedilol [Coreg] |
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Definition
| dangerous in pts with severe CHF b/c they acutely precipitate potentially fatal exaggeration of low CO; used in less severe CHF pts for long-term use; prevents down-regulation of beta-adrenergic receptor #'s & related fcns, preventing excessive tachycardia & arrhythmias; also inhibits over-expression of RAAS in CHF by inhibiting renin release from kidney |
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