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55 Cards in this Set
- Front
- Back
what drugs are used in management of stable heart failure?
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Diuretics (furosemide, thiazide, spironolactone (K+ sparing)
Vasodilators (Catopril, Emalopril, Benazopril, Lisinopril- angiotensin converting enzyme inhibitors) Positive Ionotropes- Digitalis glycosides like digoxin, digotoxin, ouabain, pimobendan Beta blockers( metoprolol, carvedolol, atenolol) aspirin and other anticoagulatnts like heparin |
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What are some diuretics used to treat stable heart failure?
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Furosemide, hydrochlororthiazide, chlorothiazide, spironolactone
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What are some vasodilators used to treat stable heart failure?
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Catopril, Emalopril, Benazopril, Lisinopril, Losartan, amlodipine, hydralizine
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How do drugs like emalopril work in the treatment of stable heart failure?
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They inhibit angiotensin converting enzyme...no RAAS compensation
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What are some positive ionotropes that are used to manage stable heart failure?
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dititalis glycosides, pimobendan
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What are some beta blockers that are used to treat stable heart failure?
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metoprolol, carvedolol, atenolol,
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How does managment of stable heart failure differ from management of emergency heart failure?
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Emergency management requires quick acting drugs with high activity that can typically be given IV.
Stable heart failure drugs alter hemodynamic properties and sympathetic and RAAS effects. |
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why are loop diuretics used in stable heart failure?
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therapeutic uses are similar to emergency heart failure. Pharmacological effects and adverse effects are the same as in emergency heart failure. They are used at lowest effective dose in stable heart failure to avoid side effects (electrolyte abnormalities, systemic alkylosis, and dehydration)
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why are other diuretics sometimes combined with furosemide diuretics in tx of stable heart failure?
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to increase diuretic activity of lasix, combat diuretic resistance due to hypertorphy of ascending loop of henle
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why do thiazide diuretics and K+ diruetics have less activity than loop diuretics?
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diuretic efficacy is moderate because less Na reabsorption occurs in the distal tubule (on 5% and 2% respective of where these drugs work.
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What electolyte abnormalities can be seen with thiazide diuretics?
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hypokalemia, hypomagensemia, hyponatremia
metabolic alkalosis increase Ca reabsorption |
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Pharmacological concerns with thaizide diuretics (how are they given, where are they eliminted and what iwll decrease effectiveness)
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given orally
excreted by kidneys decreased renal blood flow |
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why are thaizide diuretics sometimes used in heart failure tx.
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to potentiate the diuretic effect of furosemide
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adverse effects of thiazide diuretics
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dehydration and hypovolemia, electolyte imbalance, hyperglycemia and hypersenstivity reactions in patients allergic to sulfonamides, dehydration and lectorlyte abnormalites are more common when combined.
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Drugs that are considered potassium sparring diuretics are
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spironolactone, triameterene, amiloride
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How do K+ sparing diuretics cause diursis?
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competitive inhibition with aldosterone binding to receptors
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what hormone deficiency would decrease the effectiveness of K+ sparing diuretics?
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aldosterone
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how do postassium sparing diuretics effect electrolytes and protons?
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they are K+ sparing (hyperkalemia) and retain proton (acidosis)
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what other pharmacological effects of spironlactone may be more helpful than it's diuretic effect in heart failure patients?
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diuretic effect may be good for hemodynamic function (decreased preload and venous hydrostatic pressure) however the aldosterone bloackage may be more important in preventing direct myocardial injury to the heart caused by chronic elevated levels of aldosterone.
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Pharmacokinetic concerns with K+ diurectics
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given orally
onset of action is slow, long duration (2-3 days) |
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When is spironolactone used in heart failure
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to potentiate the diuretic effect of lasix
sometimes used at lower doeses not as a diuretic but as an aldosterone lbocker |
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adverse effects of potassium sparring diuretics?
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K+ and H+ retention= hyperkalemia + acidosis
potential for adverse reproduction affects |
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what diuretic used in hart failure is most likely to cause dehydration and electrolyte abnormalities?
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loop diuretics- furosemide
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ACE inhibitors include what drugs?
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Enalopril, Catopril, Lisinopril, Benazopril
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What is the effect on hemodynamics with ACE inhibitors?
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balanced vasodilation resutls in afterload reduction causing preload reduction
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How do ACE inhibitors cause vasodilation?
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they decrease Angiotensin II levels (angiotensin is a vasoconstrictor)
They also increase bradykinin levels which is a vasodilator (ACE breaks down bradykinin) |
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What are renal effects of ACE inhibitors?
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decrease water rentention because of angiotensin and aldosterone inhibition
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What is the benefit of decreased angiotensin and aldosterone in heart failue other than vasodilation and less water retention?
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less sympathetic and vasopressin release (angiotensin II increaes the activity of these systems)
Aldosterone and angiotensin blockade may prevent direct toxicity to myocardium (this may be one of the biggest benefits in heart failure given it is a weak vasodilator) |
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How are ACE inhibitors given?
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All are given orally but enalopril does have an IV form
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How are ACE inhibitors eliminated?
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most are renally eliminated but benazopril has significant billary excretion
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When are ACE inhibitors used in heart failure?
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Used in stable heart failure (shown to reduce morbidity and mortality)
would not be a very effective vasodilator in emergency heart failure and most need to be given orally a loop diuretic and ACE inhibitors are very common drugs in tx of heart failure (baseline drugs in heart failure) |
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why might ACE inhibitors drugs helpful in heart failure?
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because of hemodynamic effects (decreased resistance) but maybe more importantly b/c of decreased levels of angiotensin and aldosterone which can be toxic to the heart when chronically elevated
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what are other uses of ACE inhibitors?
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hypertension (decrease hypertension via vasodilation) and to decrease protein loss in protein losing nephropathies (less protein loss b/c they can lower intraglobmerular pressure)
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in what situation might benazopril be preferred to enalopril?
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in renal disease benazopril is preferred b/c it is eliminated by the liver
for example- cats with hypertension may have renal disease as a cause of hypertension. in this situation benazopril may be better thanenalopril due to less need for dosage modification. |
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What are the adverse effects of ACE inhibitors?
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-Excessive vasodilation can drop blood pressure
- renal enzyme elevations due to excessive vasodilation or decreaed efferent arterial dialtion. Efferent arteriol vasodilation can decrease glomerular filtration pressure and therefore decrease glomerular filtration. In particular if starting out at a low or normal glomerular pressure. - GI upset (more likely with catopril) - Increased K+ due to aldosterone inhibition -blood dysrazias, proteinuria and skin rash with catopril -cough reported in people |
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What other vasodilators can be used in stable heart failure?
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Hydralazine
Amlodopine (Ca channel blocker than mainly causes vasodilation) - can decrease afterload via vasodilation excessive doses awill decrease blood pressure and blood flow just like other vasodilator - Angiotensin II antagonist (also used for hypertension and may be beneficial in angiotensin blockade but remains to be seen if beneficial in heart failure) -Renin blockers have also been developed for use in heart failure. |
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What are some positive inotropes used in heart failure?
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pimobendan and digitalis glycosides
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Digitalis glycosides include what drugs?
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digitoxin, digoxin, and ouiabain
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What are the hemodynamic effects of digioxin in heart failure?
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increased heart contractility
Decreased heart rate increased contractility may improve cardiac output resulting in a reflex vasodilation and therefore decrease in peripherial vascular resistance |
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How do digitalis glycosides improve contractility?
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inhibit sodium potassium ATPase which causes increased sodium in cell
Increased calcium is then taken out of cell in exchange for Ca via sodium Ca exchanger resulting in increased intracellular Ca and therefore increased contractility |
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How do digitalis glycosides decrease heart rate?
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increase contractility can improve blood flow and pressure resulting in a reflex decrease in heart rate
-inhibition of sodium potasssium ATPase in baroreceptor sensitized the receptors to increases in blood pressure so that they decrease sympathetic discharge at a lower pressure. |
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What pharmacological effect do digitalis glycosides have on the kidney, GIT, and CNS
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in the kidney increase GFR
in the GIT they cause vomiting and diarrhea in CNS cause depression, disorientation, delerium |
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How are digitalis glycosides given, eliminated and excreted?
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given IV or orally
small amount undergoes hepatic metabolism (more for digitoxin) and undergoes intrahepatic recycling mainly renal excretion in dogs and horses and renal and hepatic in cats need to decrease dose in renal failure (in renal failure may be better to use digitoxin) |
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Uses of digitalis glycosides?
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Heart Failure
Used to tx heart failure due to systolic heart failure because it will increase contractility Decreased heart rate may also help as an increase in heart rate will increase myocardial oxygen demand resulting in myocaridal injury due to an oxygen deficit used to slow heart rate in tachyarrhythmias. May be used as an emergency drug in arrhythmia situation. |
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In what types of heart disease are digitalis glycosides contraindicated?
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in cases of diastolic failure associated with cardiac hypertrophy. In these cases systolic function is not a problem. May not be useful in valvular regurge (increased contractility may worsen regurge) but some feel decreased heart rate may make it useful in these cases
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What are some adverse effects of digitalis glycosides?
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GI upset
arrhythmias (tachyarrythmias and bradyarrhythmias) CNS depression very narrow therapeutic margin adverse effects are common with this drug requiring drug levels be monitored |
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what electrolyte and other abnormalities may increase digitalis toxicity and chances of arrthymias? which electrolyte abnormality is common with combined therapy?
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hypokalemia, hypomagnesemia, hypercalcemia, hypernatremia
also hypothyroidism, hyperthyrodism, hypoxemia remember that many patients on loop diuretics are hypokalemic as a side effect of the loop diuretics (often heart failure patients are on both these drugs) |
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how is digitalis toxicity monitored for and treated?
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monitor drug levels and check for clinical signs
to tx withdrawl drug, give antirrhythmic for arrhythmias, sometimes digibind and AB is given to bind digitalis glycosides |
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What is the advantage of pimobendam over other drugs such as amirinone or milrinone?
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it is a phsophodiesterase inhibitor like these drugs but is also senstitzed the myofibrils to CA. Therefore contractility is increased with less Ca in the cell. This is good because excess Ca in myocardial cells can be toxic cause arrhythmias, increase cardiac work load and oxygen consumption. It also allows it to work in times of acidosis unlike other inodilators
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why are pimobendan, milronone, and amrinone called inodialtors?
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the also cause vasodilation in addition to increased contractility via phosphodiesterase inhibition
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Why are negative ionotropes used in stable heart failure?
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the block the sympathetic system and RAAS (via BETA 1 blockade). These systems can be directly toxic to the heart.
They help improve heart fxn over a long period by preventing harmful effects of excessive sympathetic drive and also help block excessive RAAS |
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Why are BETA blockers not used in emergency heart failure?
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in emergency heart failure these drugs would take to long to work.. Could potentially decompensate the patient by decreasing heart rate and contractility.
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What beta blockers are beta 1 specific and which act on Beta 1 and BETA 2
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metopolol and atenolol are beta I specific
propanolol, timolol, and pindolol, are not beta specific caervedolol work on beta 1, beta 2 and alpha |
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side effects of beta blockers include?
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sudden withdrawal can cause tachycardia, sinus bradycardia, and decreased contracility, hypoglycemia, bronchospasm, hyperkalemia, GI side effects, sedation
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what other drug can be used in rate control in heart failure and to decrease the harmful effects of intracellular Ca?
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diltiazem (it is a Ca channel blocker)
This drug may also reduce contractility and heart rate |