How differences in the CYP2C9 gene change warfarin metabolism

Correlation Between Phenotypic Activity of CYP2C9 and Genetic Polymorphism in CYP2C9 and Warfarin Metabolism.

Not applicable Interventional Hadassah Medical Organization · NCT00162474

This study will test whether healthy adults with different CYP2C9 gene types process warfarin differently by measuring drug metabolism after dosing.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment1000 (estimated)
Ages20 Years to 50 Years
SexAll
SponsorHadassah Medical Organization Academic / other
Locations1 site (Jerusalem)
Trial IDNCT00162474 on ClinicalTrials.gov

What this trial studies

Warfarin anticoagulant effect varies widely and CYP2C9 is a key enzyme in S-warfarin metabolism. Healthy volunteers are genotyped for CYP2C9 variants and given warfarin and phenytoin to measure in vivo metabolic activity. Investigators will compare warfarin pharmacokinetics across genotype groups and correlate the phenytoin metabolic ratio with warfarin metabolism. Participants with significant illnesses, regular drug use, or known hypersensitivity to study drugs are excluded for safety and to avoid confounding results.

Who should consider this trial

Good fit: Healthy adults aged 20–50 years with no significant disease, not taking regular medications, and without known hypersensitivity to warfarin or phenytoin are ideal candidates.

Not a fit: People with significant medical conditions, regular prescription drug use, outside the 20–50 age range, or with allergies to the study drugs are unlikely to benefit or be eligible.

Why it matters

Potential benefit: If successful, the results could help tailor warfarin dosing to a person’s CYP2C9 genotype and reduce dosing errors and bleeding risk.

How similar studies have performed: Previous research has already shown that CYP2C9 variants influence warfarin dose requirements, and this study builds on that established pharmacogenetic evidence by linking metabolism measures directly to genotype.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age range of 20-50 years old
* The absence of significant disease states

Exclusion Criteria:

* Known hypersensitivity to warfarin or phenytoin
* Known hepersensitivity to penicillins or cephalosporins (Dicloxacillin part)
* The presence of significant disease states
* Regular use of drugs (including birth control pills)

Where this trial is running

Jerusalem

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions HealthyHealthy Volunteers
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.