Normal response expected based on CYP2C9 genotype. Risk of SJS/TEN dependent on HLA-B*15:02 (not tested).
Therapeutic Recommendation
Use standard dose and adjust based on clinical factors.
Intermediate Metabolizer with an enzyme Activity Score of 1.5
Clinical Implication
Decreased CYP2C9 enzyme activity.
Normal response expected based on CYP2C9 genotype. Risk of SJS/TEN dependent on HLA-B*15:02 (not tested).
Therapeutic Recommendation
Use standard dose and adjust based on clinical factors
Intermediate Metabolizer with an enzyme Activity Score 1
Clinical Implication
Decreased CYP2C9 enzyme activity.
Increased risk of adverse effects (e.g., sedation, ataxia, dizziness, leukopenia, suicidal ideation). Risk of SJS/TEN dependent on HLA-B*15:02 (not tested).
Therapeutic Recommendation
Use standard initial or loading dose for first dose, then use a ~25% dose reduction for subsequent doses. Thereafter, adjust according to therapeutic drug monitoring, response, and adverse effects.
Poor Metabolizer
Clinical Implication
Little to no CYP2C9 enzyme activity.
Increased risk of adverse effects (e.g., sedation, ataxia, dizziness, leukopenia, suicidal ideation). Risk of SJS/TEN dependent on HLA-B*15:02 (not tested).
Therapeutic Recommendation
Use standard initial or loading dose for first dose, then use a ~50% dose reduction for subsequent doses. Thereafter, adjust according to therapeutic drug monitoring, response, and adverse effects.
Unable to Genotype or Assay Failure
The analysis failed to yield an informative result and thus no genotype is reported.
Unknown Phenotype
This individual is carrying at least one allele with uncertain/unknown function and the predicted phenotype cannot be determined at this time.