CALCULATOR

Warfarin Maintenance Dose Calculator

Genetic variability contributes to interindividual differences in warfarin response. This calculator aims to help healthcare providers calculate the warfarin maintenance dose based on patients’ CYP2C9 and VKORC1 genotypes.

  • African
  • Severe liver/ kidney disease, malabsorption, chronic diarrhea
  • Presence of blood dyscrasia
  • Autoimmune diseases which interfere with coagulation
  • Pregnant patients
  • On interacting drugs other than CYP2C9 inducer and amiodarone
  • Untreated thyroid dysfunction
  • Clinically unstable - e.g. fluid overloaded, septic, hemodynamically unstable
  • Patients with increased warfarin sensitivity e.g. poor nutrition/ high bleeding risk/ recent or active bleeding/ recent major surgery (refer to NUH Warfarin guidelines)
  • Inherited protein C and protein S deficiency
Therefore, it is important to interpret the results in the context of the patient's clinical status and other concomitant drugs
Personal Information
cm
kg
Year
Genetic Information
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Concomitant Information
This calculator was created by Mr. Kim Ji Heon1, Dr. Elaine Lo2, Ms. Tan Su Ching2, A/Prof Doreen Tan3, Dr. Folefac Aminkeng3 and Prof Goh Boon Cher2,3
1Khoo Teck Puat Hospital, 90 Yishun Central, Singapore 768828
2National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074
3National University of Singapore, 21 Lower Kent Ridge Rd, Singapore 119077