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Cytochrome P-450 2C9 Isoenzyme

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Cytochrome P-450 2C9 Isoenzyme, CYP2C9

  • Precautions
  • CYP2C9 Deficiency related to Warfarin toxicity
  1. Higher risk for Warfarin toxicity and bleeding complications
  2. Start with lower doses
  3. Reaching a steady-state INR on Warfarin requires >3 months
  4. Voora (2005) Thromb Haemost 93:700-5 [PubMed]
  • Interactions
  • Metabolized by CYP2C9 (Substrates)
  • Interactions
  • Inhibitor of CYP2C9
  1. Neuropsychiatric drugs
    1. Fluoxetine (Prozac)
  2. Cardiopulmonary Drugs
    1. Amiodarone
    2. Zafirlukast (Accolate)
    3. Fluvastatin (Lescol)
  3. Antibiotics and Antifungals
    1. Fluconazole (Diflucan)
    2. Ketoconazole
    3. Metronidazole (Flagyl)
    4. Ritonavir
    5. Trimethoprim-sulfamethoxazole (Septra)
  • Interactions
  • Inducer of CYP2C9
  1. Neuropsychiatric drugs
    1. Carbamazepine
    2. Phenobarbital
    3. Phenytoin
  2. Antibiotics
    1. Rifampin