Warfarin Review

Warfarin

Warfarin Review Video

Warfarin Review

Questions

Coagulation Cascade

Warfarin indirectly inhibits formation of which factors in the coagulation cascade?

Coagulation Cascade

What factor do direct oral anticoagulants (DOACs) inhibit?

Warfarin MOA

What enzymes does warfarin directly inhibit?

  • Glutamyl Carboxylase
  • Factors II, VII, IX, X
  • VKOR-C1
  • Vitamin K 2,3-quinone reductase
  • Factors IIa, VIIa, IXa, Xa
  • Factor Xa

Warfarin Metabolism

Which isomer is the more active form of warfarin?

Warfarin Metabolism

Match the CYP enzymes with the corresponding isomer of warfarin they metabolize. 

  • S-Warfarin
    CYP2C9
  • R-Warfarin
    CYP1A2
  • R-Warfarin
    CYP3A4
  • R-Warfarin
    CYP2C19

Pharmacogenetics of Warfarin

What genetic variations in which of the following enzymes are of MOST concern for warfarin dosing?

  • CYP2C9
  • VKOR-C1
  • CYP2D6
  • CYP1A2
  • CYP3A4

INR Goals

A patient with which of the following indications would we target an INR goal of 2.5-3.5?

  • A. Fib
  • VTE
  • Mechanical AVR
  • Mechanical MVR
  • Dual AVR MR

Warfarin Identification

  • Yellow
    7.5mg
  • Pink
    1mg
  • Teal
    6mg
  • White
    10mg
  • Lavender
    2mg
  • Orange
    5mg
  • Brown
    3mg
  • Green
    2.5mg
  • Blue
    4mg

Warfarin Identification

JD comes to your pharmacy for a refill of his warfarin. However, he cannot remember the dosage of his medication. On his profile he has active prescriptions for warfarin 4mg, 5mg, 7.5mg, and 10mg. You ask if he remembers anything about the warfarin he is currently taking and he states that he takes an orange pill on Monday, Wednesday, and Friday and a yellow pill on Saturday. Based on this information which prescriptions would you refill?

  • 5mg and 10mg
  • 4mg and 10mg
  • 5mg and 7.5mg
  • 4mg and 5mg
  • 4mg and 7.5mg

Perioperative Management of Warfarin

Which of the following procedures would be considered major and need interruption of warfarin therapy and bridging?

  • Prostate resection
  • Renal biopsy
  • Hernia repair
  • Epidural
  • Dental extraction

Warfarin Interactions

Match the following situations with the correct effect on the patients INR level.

  • Significantly increased ingestion of collard greens over the past week
    Subtherapeutic
  • Initiation of oral fluconazole to treat a yeast infection
    Supratheraputic
  • Discontinuation of daily Ensure nutritional supplements
    Supratheraputic
  • Initiation of CYP2C9 inducer
    Subtherapeutic

Warfarin Interactions

What drugs can displace warfarin binding to albumin?

  • Salicylic acid
  • Loratidine
  • Bactrim
  • Atorvastatin
  • Valproic acid

Warfarin Interactions

RG is currently on warfarin due to A. Fib. He comes into your pharmacy today with a new prescription for Cordarone. You notice that his physician did not adjust his warfarin dose appropriately for initiation of this new medication. You call the physician and recommend that RG's warfarin dose should be  by  to  to avoid a significant drug interaction.