Antiplatelets+vs.+Anticoagulants+vs.+Thrombolytics

-Alter formation of platelet plug by decreasing responsiveness of platelets to stimuli that would cause them to stick and aggregate on a vessel wall. -Used to treat: -CV diseases that are prone to produce occluded vessels -Maintenance of venous and arterial grafts -Prevent cerebrovascular occlusion -Adjuncts to thrombolytic therapy -Tx of MI and prevention of reinfarction -Contraindications: Allergy, pregnancy, and lactation -Caution: Bleeding disorder, recent surgery, closed head injury -Adverse effects: Bleeding,Headache, dizziness, and weakness -Drug-to-drug interaction: Other blood-clotting drugs -**Prototype Drug:** **Aspirin** à **Indications** for: Reduction of risk of recurrent TIA’s or strokes in males w/hx of TIA due to fibrin or platelet emboli; reduction of death or nonfatal MI in pt’s w/hx of infarction or unstable angina; MI prophylaxis; also used for its anti-inflammatory, analgesic, and antipyretic effects. à **Action**: Inhibits platelet aggregation by inhibiting platelet synthesis of thromboxane A2 à A**dverse effects**: Acute aspirin toxicity w/hyperpnea, possibly leading to fever, coma, CV collapse, nausea, dyspepsia, heartburn, epigastric discomfort, GI bleeding, occult blood loss, dizziness, tinnitus, difficulty hearing, anaphylactoid rxn. -Also mentioned in lecture:
 * __1. Antiplatelet Drugs__**
 * -Anegrelide/Agrylin**: Oral drug used to treat essential thrombocythemia to reduce elevated platelet counts and decrease risk of thrombosis. Works to decrease bone marrow production of platelets, so patients need to have their platelet count monitored regularly.
 * Nursing Considerations: Plt count w/antiplatelets

-**Action:**Interfere w/coagulation process by interfering w/clotting cascade and thrombin formation. Include: Warfarin, heparin, antithrombin, argatroban, bivalirudin, desirudin. Can be used orally (warfarin) or parenterally (heparin, antithrombin, agatroban, bivalirudin) -**Adverse Effects:** BLEEDING (most common), nausea, GI upset, diarrhea, hepatic disfunction. Warfarin associated w/alopecia, dermatitis, bone marrow depression, prolonged and painful erections. -**Drug-Drug Interactions:** -Increased bleeding if heparin combined w/oral anticoagulants, salicylates, penicillins, or cephalosporins. Decreased anticoagulation w/nitroglycerin. -Warfarin: interactions with several drugs. See Table 48.3 p. 793. Careful monitoring, adjustment is necessary with warfarin dosage to prevent adverse effects. Oral drug à maintain a state of anticoagulation in sutiations where pt. is susceptible to potential clot formation. Interferes w/formation of Vitamin K dependent clotting factors in liver. Eventaul effect is a depletion of clotting factors and a prolongation of clotting times. Readily absorbed thru GI tract, metabolized in liever, excreted in urine/feces. Used to tx pt’s with afib, artificial heart valves, or valvular damage that meks them susceptible to thrombus and embolus formation. Also used to treat/prevent venous thrombosis and embolization after acute MI or pulmonary embolism. Not used during pregnancy or lactation bc of bleeding complications for mom and baby. Reversal agent: Vitamin K. Naturally occurring substance à inhibits conversion of prothrombin to thrombin à blocking conversion of fibrinogen to fibrin (final step in clot formation) à injected IV or subq à immediate onset of action. Does NOT cross placenta (some adverse fetal effects reported in pregnancy though). **Indicated for**: acute tx/prevention of venous thrombosis & pulmonary embolism/ tx of afib w/embolization; prevention of clotting in blood samples and in dialysis and venous tubing; dx and tx of disseminated intravascular coagulation. Also used as an adjunct in tx of MI and stroke. Not the drug of choice for outpatients b/c it’s injected. May be started on heparin that switched to oral warfarin. Reversal agent for Heparin: Protamine Sulfate. · Low Molecular Weight Heparins: Inhibit thrombus and clot formation by blocking factors Xa and IIa. Do not greatly affect thrombin, clotting, or prothrombin times; therefore, they cause fewer systemic adverse effects. Block angiogenesis, the process that allows cancer cells to develop new blood vessels. Are indicated for specific uses in the prevention of clots and emboli formation after certain surgeries or bed rest Naturally occurring anticoagulant. Used w/o reported adverse effects during pregnancy and lactation. Given to IV to patients w/hereditary antithrombin III deficiencies who are undergoing surgery or obstetrical procedures that put them at risk for thromboembolism. Used for replacement therapy in congenital antithrombin III deficiency. IV thrombin-inhibiting drug used to treat thrombosis in heparin induced thrombocythemia. IV drug that inhibits htrombin. Used w/aspirin to prevent ischemic events in patients undergoing transluminal coronary angioplasty.
 * __2. Anticoagulants__**
 * -Contraindicated** in presence of known allergy. Should NOT be used w/any conditions that could be compromised by increased bleeding tendencies, including hemorrhagic disorders, recent trauma, spinal puncture, GI ulcers, recent surgery, intrauterine device placement, TB, presence of indwelling catheters, threatened abortion. Contraindicated in pregnancy, renal or hepatic dz. Caution w/CHF pt’s, thyrotoxicosis, senility, or psychosis bc of potential for unexpected effects & in those w/diarrhea or fever (can alter normal clotting process by loss of Vitamin K fr. intestine or activation of plasminogen)
 * 1. Warfarin/Coumadin:**
 * Nursing considerations: PT or INR
 * 2. Heparin:**
 * Nursing Considrations: PTT
 * 3. Antithrombin/Thrombate III**:
 * 4. Argatroban/Acova:**
 * 5. Bivaliruidn/Angiomax:**

-Activate the natural anticlotting system, conversion of plasminogen to plasmin. Activation of this system breaks down fibrin threads and dissolves any formed clot. Effective only if pt. has plasminogen in the plasma. **Indications** à Tx of AMI (to dissolve clot &prevent further tissue damage, if used w/in 6h after onset of s/s), treat pulmonary emboli & eschemic stroke & to open up clotten IV catheters. **Pharmicokinetics**** à **Must be injected & are cleared fr. body after liver metabolism. Cross placenta, associated w/adverse fetal effects. **Contraindicated in:** allergy, any condition that can be worsened by dissolution of clots like: surgery, active internal bleeding CVA w/in last 2 mos., aneurysm, obstetrical delivery, organ biopsy, GI bleeding, rupture of noncompressible vessel, recent major trauma, known blood clotting defects, cerebrovascular dz, uncontrolled HTN, liver dz, pregnancy/lactation. **Adverse effects**** à **Bleeding, arrhythmias, hypotension, hypersensitivity (rahs, flushin, anaphylactic rxn). **Drug-Drug Interaction**** à ** Risk of hemorrhage increased if used with any anticoagulant or antiplatelet drug. Streptokinase/Streptase/Kabikinase: Converts endogenous plasminogen to plasmin, which breaks down fibrin clots, fibrnogen and other plasma proteins; lyses thrombi and emboli. Indicated for coronary artery thrombosis, mgt. of acute evolving transmural MI, lysis of pulmonary emboli, tx of DVT, arterial thrombosis & embolism, opening of occluded atriovenous cannulae. Adverse effects: H/A, angioneurotic edema, hypotension, skin rash, bleeding, breathing difficulties, pain fever, anaphylactic shock
 * __3. Thrombolytics__**
 * -Prototype: **