Coagulation Modifier Drugs Lilley Reading and Workbook, Chap 27

Coagulation Modifier Drugs Anticoagulants Inhibit the action or formation of clotting factors Prevent clot formation Antiplatelet drugs Inhibit platelet aggregation Prevent platelet plugs Thrombolytic drugs Lyse (break down) existing clots Hemostatic or Antifibrinolytic drugs Promote blood coagulation

Hemostasis The process that halts bleeding after injury to a blood vessel Complex relationship between substances that promote clot formation and either inhibit coagulation or dissolve a formed clot

Anticoagulants Have no direct effect on a blood clot that is already formed Used prophylactically to prevent Clot formation (thrombus) An embolus (dislodged clot)

Coagulation System “Cascade” Each activated factor serves as a catalyst that amplifies the next reaction Result is fibrin, a clot-forming substance Intrinsic pathway and extrinsic pathway

Anticoagulants: Mechanism of Action Vary, depending on drug Work on different points of the clotting cascade Do not lyse existing clots Heparin & low-molecular-weight heparins enoxaparin (Lovenox) Turn off coagulation pathway and prevent clot formation Warfarin (Coumadin) All ultimately prevent clot formation

Anticoagulants Prevention of clot formation also prevents: Stroke Myocardial infarction (MI) Deep vein thrombosis (DVT) Pulmonary embolism (PE)

Anticoagulants: Indications Used to prevent clot formation in certain settings where clot formation is likely Stroke Atrial fibrillation Myocardial infarction (MI) / Unstable Angina Deep vein thrombosis (DVT) Pulmonary embolism (PE) Indwelling devices, such as mechanical heart valves Major orthopedic surgery

Anticoagulants: Adverse Effects Bleeding Risk increases with increased dosages May be localized or systemic May also cause Nausea, vomiting, abdominal cramps, thrombocytopenia, others

Anticoagulants Heparin Monitored by activated partial thromboplastin times (aPTTs) Goal: Therapeutic range based on body weight based dosage aPTT between 1.5 – 2.5 times normal control level Parenteral – IV bolus followed by infusion Never mixed with any other medication Short half-life (1 to 2 hours) Effects reversed by protamine sulfate Obtained from sheep, cows, and pigs

Heparin: Nursing Implications Anticoagulant effects seen immediately Laboratory values are done daily to monitor coagulation effects (aPTT) Intravenous doses are usually double checked with another nurse Ensure that SC doses are given SC, not IM SC doses should be given in areas of deep subcutaneous fat, and sites rotated Bleeding precautions

Anticoagulants Low-molecular-weight heparins enoxaparin (Lovenox) dalteparin (Fragmin) More predictable anticoagulant response Do not require frequent laboratory monitoring Given subcutaneously – rotate sites Patient may be instructed for home administration Bleeding precautions Protamine sulfate can be given as an antidote in case of excessive anticoagulation

Anticoagulants warfarin sodium (Coumadin) Given orally only – usually late afternoon – same time daily Monitored by INR (INR) - 2-4 depending on diagnosis (Prothrombin time – lab-specific -- 1 ½ - 2 ½ times the control 12-15 sec) Dose changed according to INR results phytonadione (Vitamin K) can be given if toxicity occurs

Warfarin - Nursing Implications Assess: Patient history, medication history, allergies Contraindications Baseline vital signs, laboratory values Potential drug interactions—there are MANY! History of abnormal bleeding conditions Usually started 2-3 days prior to heparin infusion being discontinued - until PT-INR levels indicate adequate anticoagulation Full therapeutic effect takes several days Monitor PT-INR regularly—keep follow-up appointments Antidote is phytonadione (Vitamin K)

Warfarin -- Nursing Implications Many herbal products have potential interactions—increased bleeding may occur Capsicum pepper Garlic Ginger Gingko Ginseng Feverfew

Antiplatelet Drugs Indications Antithrombotic effects Adverse effects Reduce risk of fatal and nonfatal strokes Adverse effects Vary according to drug

Antiplatelet Drugs Prevent platelet adhesion Aspirin dipyridamole (Persantine) clopidogrel (Plavix) and ticlopidine (Ticlid) ADP inhibitors tirofiban (Aggrastat), eptifibatide (Integrilin) New class, GP IIb/IIIa inhibitors

Antiplatelet Drugs: Nursing Implications Concerns and teaching tips Same as for Anticoagulants Dipyridamole should be taken on an empty stomach Drug-drug interactions Adverse reactions to report Monitoring for abnormal bleeding

Antifibrinolytic Drugs Prevent the lysis of fibrin Results: promote clot formation Used for prevention and treatment of excessive bleeding resulting from hyperfibrinolysis or surgical complications aminocaproic acid (Amicar) desmopressin (DDAVP) Similar to ADH Also used in the treatment of diabetes insipidus

Antifibrinolytic Drugs: Indications Prevention and treatment of excessive bleeding Hyperfibrinolysis Surgical complications Excessive oozing from surgical sites such as chest tubes Reducing total blood loss and duration of bleeding in the postoperative period

Antifibrinolytic Drugs: Adverse Effects Uncommon and mild Rare reports of thrombotic events Others include: Dysrhythmia, orthostatic hypotension, bradycardia, headache, dizziness, fatigue, nausea, vomiting, abdominal cramps, diarrhea, others

Thrombolytic Drugs Drugs that break down, or lyse, preformed clots Older drugs streptokinase and urokinase Newer drugs Tissue plasminogen activator (TPA) Anisoylated plasminogen-streptokinase activator complex (APSAC)

Thrombolytic Drugs (cont’d) streptokinase (Streptase) anistreplase (Eminase) alteplase (t-PA, Activase) reteplase (Retavase) tenecteplase (TNKase) drotrecogin alfa (Xigris)

Thrombolytic Drugs: Mechanism of Action Activate the fibrinolytic system to break down the clot in the blood vessel quickly Activate plasminogen and convert it to plasmin, which can digest fibrin Reestablish blood flow to the heart muscle via coronary arteries, preventing tissue destruction

Thrombolytic Drugs: Indications Acute MI Arterial thrombolysis DVT Occlusion of shunts or catheters Pulmonary embolus Acute ischemic stroke – Code Green

Thrombolytic Drugs: Adverse Effects BLEEDING Internal Intracranial Superficial Other effects Nausea, vomiting, hypotension, anaphylactoid reactions Cardiac dysrhythmias

Nursing Implications Assess: Patient history, medication history, allergies Contraindications Baseline vital signs, laboratory values Potential drug interactions—there are MANY! History of abnormal bleeding conditions

Thrombolytic Drugs: Nursing Implications Follow strict manufacturer’s guidelines for preparation and administration Monitor IV sites for bleeding, redness, pain Monitor for bleeding from gums, mucous membranes, nose, injection sites Observe for signs of internal bleeding (decreased BP, restlessness, increased pulse)

Anticoagulants: Patient Education Education should include: Importance of regular lab testing Signs of abnormal bleeding Measures to prevent bruising, bleeding, or tissue injury Wearing a medical alert bracelet Avoiding foods high in vitamin K (tomatoes, dark leafy green vegetables) Consulting physician before taking other meds or OTC products, including herbals

Coagulation Modifier Drugs Nursing Implications Monitor for therapeutic effects Monitor for signs of excessive bleeding Bleeding of gums while brushing teeth, unexplained nosebleeds, heavier menstrual bleeding, bloody or tarry stools, bloody urine or sputum, abdominal pain, vomiting blood Monitor for adverse effects Increased BP, headache, hematoma formation, hemorrhage, shortness of breath, chills, fever

Review Antiplatelet agents act by: 1. preventing extension of existing clots. 2. preventing platelets from uniting. 3. dissolving existing clots. 4. increasing blood viscosity.

Review Doses of heparin are based on what laboratory report? 1. warfarin serum level 2. activated partial thromboplastin time (APTT) 3. Lee White clotting time 4. prothrombin time (PT) and INR

Review Nursing responsibilities involved in the administration of heparin subcutaneously include: 1. checking calculations with a second qualified nurse. 2. using a 20-gauge needle to inject the drug. 3. injecting the drug deep intramuscularly (IM). 4. aspirating before injecting the drug.

Review Clopidogrel (Plavix) is used to: 1. dissolve existing arterial blood clots. 2. prevent further movement of an embolus. 3. prevent platelet aggregation. 4. prevent extension of an existing thrombus.