Pharmacologic Profile

General Use

Prevention and treatment of thromboembolic disorders, including deep vein thrombosis (DVT), pulmonary embolism (PE), and atrial fibrillation (AF)-induced stroke and systemic thromboembolism. Also used in the management of myocardial infarction (MI) sequentially or in combination with thrombolytics and/or antiplatelet agents.

General Action and Information

Contraindications

Underlying coagulation disorders, ulcer disease, malignancy, recent surgery, or active bleeding.

Precautions

Anticoagulation should be undertaken cautiously in any patient with a potential site for bleeding. Pregnant or lactating patients should not receive warfarin or dabigatran. Heparin does not cross the placenta. All anticoagulants should be used cautiously in patients receiving epidural analgesia.

Interactions

Warfarin is highly protein bound and may displace or be displaced by other highly protein-bound drugs. The resultant interactions depend on which drug is displaced. Bleeding may be potentiated by aspirin or large doses of penicillins or penicillin-like drugs, cefotetan, valproic acid, or NSAIDs. Apixaban, dabigatran, edoxaban, and rivaroxaban have a number of other significant drug-drug interactions. See individual drugs.

Nursing Implications

Assessment

• Assess patient taking anticoagulants for signs of bleeding and hemorrhage (bleeding gums; nosebleed; unusual bruising; tarry, black stools; hematuria; ↓ hematocrit or BP; guaiac-positive stools; urine; nasogastric aspirate).
• Assess patient for evidence of thrombosis. Symptoms will depend on area of involvement.
• Lab Test Considerations: Monitor prothrombin time (PT) or international normalized ratio (INR) with warfarin therapy, activated partial thromboplastin time (aPTT) with full-dose heparin therapy, and hematocrit frequently during therapy.
• Toxicity and Overdose: If overdose occurs or anticoagulation needs to be immediately reversed, the antidote for heparins is protamine sulfate; for warfarin, the antidote is vitamin K (phytonadione); for dabigatran, the antidote is idarucizumab; for rivaroxaban and apixaban, the antidote is andexanet alfa. Administration of fresh frozen plasma or prothrombin complex concentrate may also be required in severe bleeding due to warfarin, oral direct thrombin inhibitors, or oral factor Xa inhibitors.

Implementation

• Inform all health care providers caring for patient of anticoagulant therapy. Venipunctures and injection sites require application of pressure to prevent bleeding or hematoma formation.
• If apixaban, dabigatran, edoxaban, or rivaroxaban must be discontinued for reasons other than bleeding, consider replacing with another anticoagulant; discontinuation ↑ risk of thrombotic events.
• Use an infusion pump with continuous infusions to ensure accurate dosage.

Patient/Family Teaching

• Caution patient to avoid activities leading to injury, to use a soft toothbrush and electric razor, and to report any symptoms of unusual bleeding or bruising to health care provider immediately.
• Instruct patient not to take OTC medications, especially those containing aspirin, NSAIDs, or alcohol, without advice of health care provider.
• Review foods high in vitamin K (see Food Sources for Specific Nutrients) with patients on warfarin. Patient should have consistent limited intake of these foods, as vitamin K is the antidote for warfarin and greatly alternating intake of these foods will cause the INR to fluctuate.
• Emphasize the importance of frequent lab tests to monitor the degree of anticoagulation with unfractionated heparin or warfarin.
• Instruct patient to carry identification describing medication regimen at all times and to inform all health care providers caring for patient of anticoagulant therapy before laboratory tests, treatment, or surgery.

Evaluation/Desired Outcomes

• Prevention of undesired clotting and its sequelae without signs of hemorrhage. Prevention of stroke, MI, and death in patients at risk.