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BLOOD AND BLOOD FORMING ORGANS › ANTITHROMBOTIC AGENTS › ANTITHROMBOTIC AGENTS › Vitamin K antagonists
phenindione
B01AA02
Adult Dosing
- Initial dose: 100-200 mg on day 1, followed by 50-100 mg on day 2
- Maintenance dose: 25-100 mg daily adjusted based on INR (target range typically 2.0-3.0)
Pediatric Dosing
- Safety and efficacy not established; use generally avoided in pediatric patients
Indications
- Prophylaxis and treatment of venous thrombosis and pulmonary embolism
- Prevention of thromboembolic complications associated with atrial fibrillation or cardiac valve replacement
Mechanism of Action
- Vitamin K antagonist that inhibits the synthesis of vitamin K-dependent clotting factors (II, VII, IX, and X) and anticoagulant proteins C and S
Contraindications
- Hypersensitivity to phenindione
- Significant bleeding risk or active bleeding conditions
- Severe hepatic impairment
- Severe renal impairment
- Pregnancy (teratogenic and causes fetal bleeding)
- Uncontrolled severe hypertension
Adverse Reactions
- Major and minor hemorrhage
- Hypersensitivity reactions including severe hepatitis, fever, skin rash, and eosinophilia
- Agranulocytosis and leukopenia
- Nausea, diarrhea, and jaundice
Drug Interactions
- Enhanced anticoagulant effect and increased bleeding risk with CYP2C9 inhibitors, NSAIDs, antiplatelet agents, and broad-spectrum antibiotics
- Reduced anticoagulant efficacy with CYP2C9 inducers and vitamin K-rich foods
- Potentiation of effect by amiodarone, thyroid hormones, and various statins
Curated Content: Needs Vetting Before Put to Clinical Use