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Pharm 3 Test 2
Anticoagulants and Heart failure
Question | Answer |
---|---|
Digoxin benefits heart failure how? (1) | decreased sympathetic tone (HR reduced = more complete ventricular filling; afterload is reduced =more complete ventricular emptying; venous pressure reduced = decrease in cardiac distention, pulmonary congestion, peripheral edema) |
What is the second way that digoxin benefits heart failure? | increased urine production from increased renal blood flow leading to reduced blood volume= decreased cardiac distention, pulmonary congestion, and peripheral edema |
What is the third way that dig can benefit heart failure? | decreased renin release from increased arterial pressure causing less aldosterone and angiotensin II= decreased vasoconstriction, afterload, venous pressure, and retention of sodium and water. |
What are the effects digoxin has on the electrical part of the heart? | Can alter the electrical activity in noncontractile tissue (SA node, AV node, Purkinje fibers) as well as ventricular muscle (altering automaticity, refractoriness, impulse conduction) |
What is the most serious adverse effect of digoxin? | Cardiac dysrhythmias (caused by altering the electrical activity) |
What is the most common adverse effect of digoxin? | AV block with escape beats |
What are the most dangerous adverse effects of digoxin? | Ventricular flutter and fibrillation |
If dig is used in dosages recommended, dysrhythmias are... | uncommon. |
What are predisposing factors to dysrhythmias when taking digoxin? | hypokalemia ( most common cause secondary to diuretic use), elevated dig levels, (low therapeutic range, slightly > increase risk of toxicity), heart disease (greatly increases the risk of dig to cause dysrhythmias) |
What do you need to obtain to diagnose digoxin induced dysrhythmias? | Dig level, electrolytes, EKG |
How do you manage digoxin induced dysrhythmias? | withdraw dig and K+ wasting diuretics, monitor K+ levels, may need antidysrhythmic= phenytoin and lidocaine (most effective), treat bradycardia with atropine |
If OD of digoxin is severe, may need Fab antibody fragments (Digibind) that works how? | Binds dig preventing it from acting |
What are other adverse effects of digoxin? | anorexia, N/V, blurred vision, yellow tinge to vision, and appearance of halos around dark objects, and frequently precede development of dysrhythmias |
Dig and Diuretics together cause... | thiazides and loops can cause loss of K+ and increase the risk of dig induced dysrhythmias |
Dig with ACEI and ARBs cause... | can increase K+ and decrease therapeutic responses to dig |
Dig with Sympathomimetics cause... | dopamine and dobutamine can add to the positive inotropic effects on the heart |
Dig and Quinidine cause.. | plasma levels of dig to rise |
Dig and Verapamil cause... | can significantly increase levels of dig |
What is the half-life of digoxin? | 1.5 days without loading dose, takes 6 days (4 half-lives) to reach plateau levels. If D/C'd takes 6 days to be eliminated. |
Cardiac Glycosides have... | profound effects on the mechanical and electrical properties of the heart |
Digoxin is indicated for what? | Heart failure and dysrhythmias |
Digoxin works by? | reducing symptoms, increase exercise tolerance, and decrease hospitalizations. |
Does digoxin prolong life? | NO, in women it may shorten life |
What effects does digoxin have on the heart? | positive inotropic action = increases the force of the ventricular contraction |
First line drugs for all with s/s of volume overload. By reducing blood volume, decreasing venous pressure, arterial pressure, cardiac dilation, and pulmonary and peripheral edema is... | Diuretics |
Thiazides... | produce moderate diuresis, used for long-term therapy when edema is not too great, NOT for low GFR |
Loop diuretics | produce profound diuresis, preferred when cardiac output is greatly reduced, drug of choice with severe HF. Promote fluid loss when GFR is low. |
Potassium sparing | promote only scant diuresis, used to counteract potassium loss caused by thiazides and loops. Spironolactone prolongs life in HF by blocking aldosterone receptors. |
What drug is large molecular weight and prepared from lungs of cattle and intestines of pigs? | Heparin |
What drug has the presence of many negatively charged groups in structure, thus, highly polar and cannot readily cross membranes (GI tract) and cannot be taken PO. | Heparin |
Heparin works by doing what? | Promoting the inactivation of clotting factors, ultimately suppressing formation of fibrin. Since fibrin forms the framework of thrombi in veins, useful for prophylaxis of venous thrombosis. |
In combination with __________ , heparin acts directly to inhibit clotting factor activity, thereby effects develop quickly (within minutes of IV dose) | antithrombin III |
Heparin binds non-specifically to? | plasma proteins, mononuclear cells, and endothelial cells; free heparin highly variable, needs close monitoring |
When do the effects of heparin begin? | Immediately; duration is brief (hours) and half-life is short (1 1/2 hr). |
What are the uses of heparin? | PE, evolving stroke, DVT, heart surgery, renal dialysis, prevention of venous thrombosis, DIC, MI, lab samples, stored blood in vitro, preferred for anticoagulation in pregnancy |
What are the adverse reactions of heparin? | hemorrhage (10%), can be fatal Thrombocytopenia, hypersensitivity, local irritation, hematoma, osteoporosis with long-term use. |
What are the signs of blood loss? | decreased BP, increase heart rate, bruises, petechiae, hematomas, red or black stools, cloudy or discolored urine, pelvic pain, HA, faintness, lumbar pain. |
To decrease DVTs how much heparin do you give? | 5,000 units 2 hours before surgery |
What is heparin contraindicated with? | thrombocytopenia, uncontrolled bleeding, surgery of the eye, brain or spinal cord, lumbar puncture and regional anesthesia. |
What should you use extreme caution with while taking heparin? | hemophilia, increased capillary permeability, dissecting aneurysm, PUD, HTN, threatened abortion, liver, kidney disease |
Heparin and drugs that depress platelet aggregation can? | cause increased risk of bleeding |
What lab results should be monitored with heparin? | Activated partial thromboplastin time (APTT). Normal is 40 sec. Therapeutic levels 1.5- 2 times (60 to 80 sec). |
What two types of heparin are there? | sodium and calcium. Administered in units. |
Low dose heparin is used for? | pre and post surgical prophylaxis of thrombosis |
Intermittent IV therapy of heparin, will the levels fluctuate? | yes |
Where do you give the subcutaneous injections of heparin? | abdomen, rotate sites, not within 2 in of umbilicus Do not massage or aspirate |
What is the antidote for heparin? | protamine sulfate- small protein with multiple positive charged groups that bond to negative heparin forming inactive bond. Neutralization occurs immediately and lasts for 2 hours. Slow IV=20mg/min or 50 mg/min) 1mg will inactivate 100 units of heparin |
Heparin preparations composed of molecules that are shorter than those found in standard heparin are... | as effective, may be given on fixed-dose schedule, and no APTT monitoring required. Much less able to inactivate thrombin. Plasma levels highly predictable. |
What is the half life of low molecular heparin? | 2-4 times longer than large molecular weigh heparins |
What is low molecular weight heparins used for? | Pulmonary thrombolism, DVT, hip and knee replacement surgeries Given SQ, QD, BID and based on body weight |
What are the adverse effects of Lovenox, Fragmin, Oraran, and Normiflo? | same as heparin but fewer incidences of bleeding and thrombocytopenia; may be used at home; cost is higher than heparin but no routine lab work or f/u's |
Coumadin acts as... | antagonist of vitamin K (required by clotting factors thereby blocking their action); absorbed readily; 99% bound to albumin in blood, which causes more free drugs of other stuff |
When does Coumadin start working? | Onset 36-72 hours (not good in emergencies), half-life is 42 hours (varies), peak effect 5-7 days; D/C effects last several days |
What are the uses of Coumadin | prevention of venous thrombosis and PE, prosthetic heart valves, a-fib; off label use- prevention of TIAs and to reduce recurrent MI. |
What are the adverse effects of Coumadin? | hemorrhage (commonly first seen as bleeding in gingiva): if severe may need fresh or frozen plasma to replace clotting factors, or use of vitamin K (phytonadione) to overcome the block caused by coumarins. |
What are the contraindications of Coumadin? | Pregnancy: category X (crosses the placenta), lactation (enters breast milk), severe thrombocytopenia, uncontrolled bleeding, lumbar puncture, eye, brain, or spinal surgery, vit K deficiency, liver disease, alcoholism, hypersensitivity. |
Use extreme caution with Coumadin... | hemophilia, increased capillary permeability, dissecting aneurysm, GI ulcers, severe HTN, threatened abortion |
What labs do you monitor with Coumadin? | PT/INR- multiples observed PT by a correction factor. the object of treatment is to raise the INR to appropriate value. Usually 2-3. Adjust dose by result. |
How often is PT measured when on Coumadin? | Measure daily during the first five days, 2 times a wee for 1-2 weeks, 1 time a week for 1-2 months, then every 2-4 weeks. |