Anticoagulants- Chapter 26.pptx

Chapter 26 Coagulation Modifier Drugs  Hemostasis  General term for any process that stops bleeding  Coagulation is hemostasis that occurs because of the physiologic clotting of blood.  Complex relationship between substances that promote clot formation and e...

Chapter 26 Coagulation Modifier Drugs  Hemostasis  General term for any process that stops bleeding  Coagulation is hemostasis that occurs because of the physiologic clotting of blood.  Complex relationship between substances that promote clot formation and either inhibit coagulation or dissolve a formed clot  Thrombus: technical term for a blood clot  Embolus: thrombus that moves through blood vessels 2  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 3  Fibrinolytic System  Initiates the breakdown of clots and serves to balance the clotting process  Fibrinolysis: mechanism by which formed thrombi are lysed to prevent excessive clot formation and blood vessel blockage 4  Fibrinolytic System (Cont.)  Fibrin in the clot binds to a circulating protein known as plasminogen. This binding converts plasminogen to plasmin.  Plasmin is the enzymatic protein that eventually breaks down the fibrin thrombus into fibrin degradation products. This keeps the thrombus localized to prevent it from becoming an embolus. 5  Hemophilia  Rare genetic disorder  Natural coagulation and hemostasis factors are limited or absent.  Patients with hemophilia can bleed to death if coagulation factors are not given.  Two types inhibit platelet aggregation  Factor VII deficiency  Factor VIII and/or factor IX deficiency 6  Pharmacology Overview  Drugs that affect coagulation are some of the most dangerous drugs used today.  Numerous factors can affect their action. 7  Coagulation Modifier Drugs  Anticoagulants  Inhibit the action or formation of clotting factors  Prevent clot formation  Antiplatelet drugs  Inhibit platelet aggregation  Prevent platelet plugs 8 Coagulation Modifier Drugs (Cont.)  Hemorheologic drugs  Alter platelet function without preventing the platelets from working  Thrombolytic drugs  Lyse (break down) existing clots  Antifibrinolytic or hemostatic  Promote blood coagulation 9  Anticoagulants  Also known as antithrombotic drugs  Have no direct effect on a blood clot that is already formed  Prevent intravascular thrombosis by decreasing blood coagulability  Used prophylactically to prevent  Clot formation (thrombus)  An embolus (dislodged clot) 10  Embolus  Thromboembolic events  Myocardial infarction (MI): embolus lodges in a coronary artery  Stroke: embolus obstructs a brain vessel  Pulmonary emboli: embolus in the pulmonary circulation  Deep vein thrombosis (DVT): embolus goes to a vein in the leg 11  Anticoagulants--Heparins  Heparins  Action: inhibit clotting factors IIa (thrombin) and Xa  Unfractionated heparin: “heparin”  Low–molecular-weight heparins (LMWHs) Enoxaparin (Lovenox) Dalteparin (Fragmin) 12  Anticoagulants—Heparins (Cont.)  Heparins—part 2  Unfractionated heparin (heparin)  Relatively large molecule that is derived from animal sources  Frequent laboratory monitoring for bleeding times such as aPTT  Heparin for catheter flush (10 to 100 units/mL): no monitoring is needed 13  Anticoagulants--Heparins (Cont.)  Heparins—part 3  Low Molecular Weight Heparins (LMWH)  Enoxaparin (Lovenox) and dalteparin (Fragmin)  Synthetic smaller molecular structure  More predictable anticoagulant response  Frequent laboratory monitoring of bleeding times using tests such as aPTT not needed 14  Anticoagulants (Cont.)  Coumarins  Action: inhibit vitamin K–dependent clotting factors II, VII, IX, and X  Warfarin (Coumadin)  Warfarin (Coumadin)  Inhibits vitamin K synthesis by bacteria in the gastrointestinal tract  Inhibits production of vitamin K–dependent clotting factors II, VII, IX, and X, which are normally synthesized in the liver  Final effect prevention of clot formation 15  Anticoagulants: Factor Xa Drugs  Factor Xa Inhibitor  Fondaparinux (Arixtra)  Direct Oral Anticoagulants  Rivaroxaban (Xarelto)  Apixaban (Eliquis)  Edoxaban (Savaysa)  Betrixaban (Bevyxxa)  Inhibit thrombosis by their specific action against factor Xa 16  Anticoagulants  Direct thrombin inhibitors  Action: inhibit thrombin (factor IIa)  Natural Human antithrombin III (Thrombate)  Synthetic Lepirudin (Refludan) Argatroban (Argatroban) Bivalirudin (Angiomax) Dabigatran (Pradaxa) (oral) 17  Anticoagulants: Indications  Used to prevent clot formation in certain settings in which clot formation is likely  MI  Unstable angina  Atrial fibrillation  Indwelling devices, such as mechanical heart valves  Major orthopedic surgery 18  Anticoagulants: Contraindications  Drug allergy  Any acute bleeding process or high risk for such an occurrence.  Warfarin is strongly contraindicated in pregnancy.  Other anticoagulants are rated in lower pregnancy categories (B or C).  **LMWHs are contraindicated in patients with an indwelling epidural catheter due to risk of epidural hematoma. 19  Anticoagulants: Adverse Effects  Bleeding  Risk increases with increased dosages.  May be localized or systemic  May also cause:  Heparin-induced thrombocytopenia (HIT)  Nausea, vomiting, abdominal cramps, thrombocytopenia, others  Use of warfarin: can cause skin necrosis and “purple toes” syndrome 20  Heparin-Induced Thrombocytopenia  Type I  Gradual reduction in platelets  Heparin therapy can generally be continued.  Type II  Acute fall in the number of platelets (more than 50% reduction from baseline)  Discontinue heparin. 21  Heparin-Induced Thrombocytopenia (Cont.)  Clinical manifestations  Thrombosis that can be fatal  Treatment: thrombin inhibitors lepirudin and argatroban 22 Treatment: Toxic Effects of Heparin  Symptoms: hematuria, melena (blood in the stool), petechiae, ecchymoses, and gum or mucous membrane bleeding  Stop drug immediately.  Intravenous (IV) protamine sulfate: 1 mg of protamine can reverse the effects of 100 units of heparin. 23  Treatment: Toxic Effects of Warfarin  Discontinue the warfarin.  May take 36 to 42 hours before the liver can resynthesize enough clotting factors to reverse the warfarin effects  Vitamin K1 (phytonadione) can hasten the return to normal coagulation.  High doses of vitamin K (10 mg) given IV will reverse the anticoagulation within 6 hours. 24  Treatment: Toxic Effects of Warfarin (Cont.)  Caution: when vitamin K is given, warfarin resistance will occur for up to 7 days.  Severe bleeding: transfusions of human plasma or clotting factor concentrates.  Life-threatening bleeding from warfarin: Kcentra and Profiline  IV vitamin K: risk of anaphylaxis. Risk is diminished by diluting it and giving it over 30 minutes. 25  Idarucizumab (Praxbind)  Specific antidote for dabigatran  Reverses the anticoagulant effects for dabigatran for emergency surgery or in life- threatening or uncontrolled bleeding 26  Andexxa (Coagulation Factor Xa [recombinant] Inactivated-zhzo)  Specific antidote factor Xa inhibitor  Rivaroxaban (Xarelto) & Apixaban (Eliquis)  Used for life-threatening or uncontrolled bleeding  Black Box Warning for thromboembolic events MI, ischemic stroke, cardiac arrest, sudden death 27  Drug Interactions: Anticoagulants  Enzyme inhibition of metabolism  Displacement of the drug from inactive protein- binding sites  Decrease in vitamin K absorption or synthesis by the bacterial flora of the large intestines  Alteration in the platelet count or activity 28  Drug Interactions: Anticoagulants  ALWAYS question an order if two anticoagulants are ordered!  EXCEPTION: Bridge therapy with heparin or enoxaparin and PO warfarin 29  Argatroban  Synthetic direct thrombin inhibitor  Used for active HIT and percutaneous coronary intervention procedures in patients at risk for HIT  Only given IV 30  Dabigatran (Pradaxa)  First oral direct thrombin inhibitor that is approved for prevention of strokes and thrombosis in patients with non-valvular atrial fibrillation  Prodrug that becomes activated in the liver  Specifically and reversibly binds to both free and clot- bound thrombin  Dose dependent on renal function  Adverse effects: bleeding, GI bleeding  No coagulation monitoring is required. 31  Enoxaparin (Lovenox)  Prototypical LMWH  Greater affinity for factor Xa than for factor Iia  Higher degree of bioavailability and longer elimination half-life  Lab monitoring is not necessary.  Injectable form  Used for prophylaxis and treatment  Pre-filled syringes  Do not expel air bubble 32  Heparin  Natural anticoagulant obtained from the lungs or intestinal mucosa of pigs  10 to 40,000 units/mL  DVT prophylaxis: 5000 units subcutaneously two or three times a day; aPTT does not need to be monitored when used for prophylaxis  When heparin is used therapeutically (for treatment), continuous IV infusion. Measurement of aPTT (usually every 6 hours until therapeutic effects are seen) is necessary. 33  Rivaroxaban (Xarelto)  First oral factor Xa inhibitor  Used for prevention of strokes in patients with a- fib; post-op thromboprophylaxis with orthopedic surgeries; treatment of DVT and PE  Adverse reactions: Peripheral edema, dizziness, headache, bruising, diarrhea, hematuria, and bleeding 34  Warfarin (Coumadin)  Coumadin  Most commonly prescribed oral anticoagulant  Careful monitoring of the prothrombin time/international normalized ratio (PT/INR)  A normal INR (without warfarin) is 1.0, but a therapeutic INR (with warfarin) ranges from 2 to 3.5, depending on the indication for use of the drug (e.g., atrial fibrillation, thromboprevention, prosthetic heart valve).  Variations in certain genes, CYP2CP and VKORC1  Many drug interactions  Dietary considerations 35  Audience Response System Question #1 A patient is receiving an IV infusion of heparin and was started on warfarin therapy the night before. Which statement is most correct? A. The patient is receiving a double dose of anticoagulants. B. The heparin therapy was ineffective, so the warfarin was started. C. The heparin provides anticoagulation until therapeutic levels of warfarin are reached. D. The heparin and warfarin work together synergistically to provide anticoagulation. NOTE: No input is required to proceed. 36  Answer to System Question #1 ANS: C Heparin has a faster onset and therefore is used to provide anticoagulation until therapeutic levels of warfarin are reached. 37  Antiplatelet Drugs  Work to prevent platelet adhesion at the site of blood vessel injury  Platelets normally flow through blood vessels without adhering to their surfaces  Collagen from damaged vessels stimulate platelet adhesion 38  Antiplatelet Drugs (Cont.)  Prevent platelet adhesion  Aspirin  Cilostazol (Pletal)  Clopidogrel (Plavix)  Prasugrel (Effient)  Ticagrelor (Brilinta)  Treprostinil (Remodulin)  Abciximab (ReoPro)  Eptifibatide (Integrilin)  Tirofiban (Aggrastat)  Anagrelide (Agrylin)  Dipyridamole (Persantine)  Vorapaxar (Zontivity) 39  Antiplatelet Drugs: Indications and Adverse Effects  Antithrombotic effects  Adverse effects  Vary according to drug 40  Aspirin  Available in many combinations with other prescription and nonprescription drugs  Contraindicated for flulike symptoms in children and teenagers  Reye’s syndrome  Aspiring and dipyridamole (Aggrenox)  Used for antiplatelet purposes 41  Clopidogrel (Plavix)  Most widely used ADP inhibitor  Oral use  Prasugrel (Effient), ticagrelor (Brilinta)  Similar to clopidogrel  Many drug interactions 42  Eptifibatide (Integrilin)  GP Iib/IIIa inhibitor  Usually administered in an ICU or cardiac catheterization lab setting  IV use  Others:  Tirofiban (Aggrastat)  Abciximab (ReoPro) 43  Thrombolytic Drugs  Drugs that break down, or lyse, preformed clots  Older drugs  Streptokinase and urokinase  Current drugs: t-plasminogen activators (tPa)  Alteplase (Activase, Cathflo Activase)  Tenecteplase (TNKase) 44  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 45  Thrombolytic Drugs: Indications  Acute MI  Arterial thrombolysis  DVT  Occlusion of shunts or catheters  Pulmonary embolus  Acute ischemic stroke 46  Thrombolytic Drugs: Adverse Effects  Bleeding  Internal  Intracranial  Superficial  Other effects  Nausea, vomiting, hypotension, anaphylactoid reactions  Cardiac dysrhythmias; can be dangerous 47  Audience Response System Question #2 A patient is receiving an IV infusion of a thrombolytic drug during treatment for an acute MI. The nurse notices that there is a slight amount of bleeding from the antecubital area where venous lab work was drawn. What will the nurse do first? A. Monitor the site for further bleeding. B. Apply pressure to the site with a gauze pad. C. Slow the rate of infusion of the thrombolytic drug. D. Stop the infusion of the thrombolytic drug. NOTE: No input is required to proceed. 48  Answer to System Question #2 ANS: B The most common undesirable effect of thrombolytic therapy is internal, intracranial, and superficial bleeding. If invasive procedures must be performed or injections given, appropriate pressure should be applied to bleeding sites, and all areas of venous or arterial catheter insertion should be closely watched for bleeding. This type of superficial bleeding is to be expected and does not warrant cessation of the thrombolytic therapy. 49  Alteplase (Activase)  t-PA made through recombinant DNA techniques  Fibrin specific so does not produce a systemic lytic state  Present in the body in a natural state  Very short half-life (5 minutes)  Indications: MI, strokes  Smaller doses to flush clogged IV or arterial lines (CathFlo Activase) 50  Antifibrinolytic Drugs  Prevent the lysis of fibrin  Result in promoting clot formation  Used for prevention and treatment of excessive bleeding resulting from hyperfibrinolysis or surgical complications  Treatment of hemophilia or von Willebrand’s disease  Aminocaproic acid (Amicar)  Tranexamic acid (Cyklokapron)  Desmopressin (DDAVP) 51  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 52  Aminocaproic Acid (Amicar)  Synthetic antifibrinolytic drug  Prevents and controls excessive bleeding that result from surgery or overactivity of fibrinolytic system  Oral or parenteral 53  Desmopressin (DDAVP)  Synthetic polypeptide  Similar to vasopressin, which is an antidiuretic hormone  Indications: diabetes insipidus; hemophilia  Nasal spray: used for nocturnal enuresis 54  Nursing Implications  Assess  Patient history, medication history, allergies  Contraindications  Baseline vital signs, laboratory values  Potential drug interactions  History of abnormal bleeding conditions 55  Heparin: Nursing Implications  IV doses are usually double checked with another nurse.  Ensure that subcutaneous doses are given subcutaneously, not intramuscularly.  Subcutaneous doses should be given in areas of deep subcutaneous fat and sites rotated. 56 Heparin: Nursing Implications (Cont.)  Do not give subcutaneous doses within 2 inches of:  The umbilicus, abdominal incisions, open wounds, scars, drainage tubes, or stomas  Do not aspirate subcutaneous injections or massage the injection site  May cause hematoma formation 57  Heparin: Nursing Implications (Cont.)  IV doses may be given by bolus or IV infusions.  Anticoagulant effects are seen immediately.  Laboratory values are done daily to monitor coagulation effects (aPTT).  Protamine sulfate can be given as an antidote in case of excessive anticoagulation. 58  LWMHs: Nursing Implications  Given subcutaneously in the abdomen  Rotate injection sites.  Protamine sulfate can be given as an antidote in case of excessive anticoagulation. 59  Warfarin (Coumadin): Nursing Implications  May be started while the patient is still on heparin until PT/INR levels indicate adequate anticoagulation  Full therapeutic effect takes several days.  Monitor PT/INR regularly; keep follow-up appointments.  Antidote is vitamin K. 60  Audience Response System Question #3 A 75-year-old man fell at home and hit his head against a table. His wife reports to their daughter that he does not have cuts or scratches, but there is a small lump on his upper scalp. She does not see any blood. He is taking warfarin and an antidysrhythmic as part of his treatment for chronic atrial fibrillation. What is the main concern at this time? A.Pressure should be applied to the lump for 3 to 5 minutes. B.He will need to take two doses of warfarin tonight to prevent blood clotting. C.He needs to be examined for possible internal bleeding from the fall. D.As long as there is no bleeding, there is no concern. NOTE: No input is required to proceed. 61  Answer to System Question #3 ANS: C Careful examination will be needed to ensure that there is no hematoma or other internal bleeding as a result of the fall even if superficial bleeding is not noted. 62  Warfarin (Coumadin): Nursing Implications  Many herbal products have potential interactions; increased bleeding may occur  Capsicum pepper  Garlic  Ginger  Ginkgo  St. John’s wort  Feverfew  Dong quai 63  Audience Response System Question #4 A 72-year-old woman is taking an over-the-counter multivitamin that contains ginkgo. Her physician has recommended that she start taking low-dose aspirin therapy as part of her treatment for transient ischemic attacks. What is the concern with taking these two drugs together? A. Increased risk of gastric ulcer B. Decreased action of the aspirin because of the interaction with the ginkgo C. Increased risk of bleeding because of the ginkgo D. Antagonism of the action of the aspirin because of the multivitamins NOTE: No input is required to proceed. 64  Answer to System Question #4 ANS: C Ginkgo may cause some increased bleeding times, so taking aspirin with ginkgo may put the patient at a higher risk for bleeding episodes. 65  Anticoagulants: Patient Education  Education should include:  Importance of regular laboratory testing  Signs of abnormal bleeding  Measures to prevent bruising, bleeding, and tissue injury  Wearing a medical alert bracelet  Consistent intake of foods high in vitamin K (tomatoes, dark leafy green vegetables)  Consulting physician before taking other drugs or over-the-counter products, including herbals 66  Antiplatelet Drugs: Nursing Implications  Concerns and teaching tips same as for anticoagulants  Drug-drug interactions  Adverse reactions to report  Monitoring for abnormal bleeding 67  Thrombolytic Drugs: Nursing Implications  Follow strict manufacturer’s guidelines for preparation and administration.  Monitor IV sites for bleeding, redness, and pain.  Monitor for bleeding from gums, mucous membranes, nose, and injection sites.  Observe for signs of internal bleeding (decreased blood pressure, restlessness, increased pulse). 68  Case Study The nurse is caring for a patient receiving IV heparin therapy for treatment of a pulmonary embolus. The patient is being converted to warfarin (Coumadin) therapy. The following questions relate nursing considerations when caring for this patient. 69  Case Study (Cont.) 1. Nursing considerations for conversion of IV heparin to oral warfarin (Coumadin) therapy will include A. immediate discontinuation of IV heparin and administration of oral warfarin (Coumadin) therapy only. B. overlapping therapy of IV heparin and warfarin are for at least 5 days. C. monitoring the INR and stopping the IV heparin when the INR is 1.0. 70 Answer to Case Study Question #1 ANS: B When the oral anticoagulant warfarin is prescribed, therapy is often initiated while the patient is still receiving heparin. This overlapping is done purposefully to allow time for the blood levels of warfarin to rise so that when the heparin is eventually discontinued, therapeutic anticoagulation levels of warfarin will have been achieved. Recommendations for overlapping therapy of heparin and warfarin are for at least 5 days; the heparin is stopped after 5 days when the INR is above 2. 71  Case Study 2. When converting from IV heparin to oral warfarin (Coumadin) therapy, the prescriber monitors which of the following to determine the next appropriate dose of warfarin? A. Platelet levels B. aPTT C. Red blood cell count D. PT/INR 72 Answer to Case Study Question #2 ANS: D For conversion from heparin to an oral anticoagulant such as warfarin, the dose of the oral drug is the usual initial dosage amount, with the prescriber using the PT/INR levels to determine the next appropriate dosage of warfarin. When there is continuous therapeutic anticoagulation coverage and warfarin has reached therapeutic levels, the heparin or LMWH may be discontinued without tapering. 73  Case Study 3. Which of the following should the nurse include when providing dietary teaching for the patient receiving warfarin (Coumadin) therapy? A. Avoid eating large amounts of food high in Vitamin K. B. Cranberry juice will provide you with needed nutrients while taking Coumadin. C. You must never eat spinach. D. You can only eat lettuce once a month. 74 Answer to Case Study Question #3 ANS: A For patients taking warfarin therapy, it is recommended to avoid eating or drinking large amounts of kale, spinach, Brussels sprouts, collard or mustard greens, lettuce, chard, and green tea. It is essential to take in foods with a consistent amount of Vitamin K each day. Beverages that may increase the effect of warfarin and to be avoided include cranberry juice and alcohol. 75  Case Study 4. The patient accidentally takes too much of the prescribed warfarin (Coumadin) and is readmitted to the hospital with bleeding. Which drug can the nurse anticipates administrating? A. Protamine sulfate B. Alteplase (Activase, Cathflo Activase) C. Reteplase (Retavase) D. Vitamin K 76 Answer to Case Study Question #4 ANS: D High doses of vitamin K (10 mg) given IV will reverse the anticoagulation of warfarin within 6 hours. Protamine sulfate is used to reverse heparin. Alteplase and reteplase are thrombolytics. 77