Warfarin

INTRODUCTION

Indications

Prophylaxis and treatment of Venous thrombosis, Pulmonary embolism, Atrial fibrillation with embolization. Management of myocardial infarction: ↓ risk of death, ↓ risk of subsequent MI, ↓ risk of future thromboembolic events. Prevention of thrombus formation and embolization after prosthetic valve placement.

Action

Interferes with hepatic synthesis of vitamin K–dependent clotting factors (II, VII, IX, and X). Therapeutic Effects: Prevention of thromboembolic events.

Adverse Reactions/Side Effects

GI: cramps, nausea. Derm: dermal necrosis. Hemat: BLEEDING. Misc: fever.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Watch for signs of bleeding and hemorrhage, including bleeding gums, nosebleeds, unusual bruising, coughing up blood, black/tarry stools, hematuria, or a fall in hematocrit or blood pressure. Notify physician or nursing staff immediately if warfarin causes excessive anticoagulation.

• Monitor any appreciable symptoms of DVT such as pain, swelling, warmth, and redness to determine if drug therapy is effective in preventing or reducing venous thrombosis. Request or administer objective tests (Doppler ultrasound) if symptoms increase.

• In patients with deep vein thrombosis (DVT), watch for signs of pulmonary embolism such as shortness of breath, chest pain, cough, and bloody sputum. Notify physician or nursing staff immediately if these signs occur.

• Monitor skin reactions, and report any severe or untoward reactions such as dermal necrosis.

Interventions

• Use caution with any physical interventions that could increase bleeding, including wound débridement, chest percussion, joint mobilization, and application of local heat.

• Recommend or implement other physical methods to decrease DVT and prevent thromboembolism, including graduated compression stockings and intermittent pneumatic compression pumps.

• Implement early mobilization and ambulation to reduce the risk of new or increased DVT. Early ambulation appears to be safe in patients with DVT if the patient is receiving adequate anticoagulant therapy (INR values in acceptable range), does not have an active pulmonary embolism, or have other risk factors that contraindicate ambulation.

Patient/Client-Related Instruction

• Instruct patient to immediately report signs of GI bleeding, including abdominal pain, vomiting blood, blood in stools, or black, tarry stools.

• Remind patient that excessive vitamin K intake negates warfarin's therapeutic effects. Refer patient to the physician or a nutritionist regarding appropriate dietary intake of foods rich in vitamin K (leafy green vegetables, dairy products, and so forth).

• Instruct patient or family/caregivers to report other troublesome side effects such fever, nausea, or stomach cramps.

Pharmacokinetics

Absorption: Well absorbed from the GI tract after oral administration.

Distribution: Crosses the placenta but does not enter breast milk.

Protein Binding: 99%.

Metabolism and Excretion: Metabolized by the ...