A provider may consider testing for CYP2D6 variants prior to starting tamoxifen for breast cancer to:
1. Ensure the patient will not have increased adverse drug reactions to the tamoxifen
2. Identify potential drug-drug interactions that may occur with tamoxifen
3. Reduce the likelihood of therapeutic failure with tamoxifen treatment
4. Identify poor metabolizers of tamoxifen
Question 2
Ultra-rapid metabolizers of drugs may have:
1. To have dosages of drugs adjusted downward to prevent drug accumulation
2. Active drug rapidly metabolized into inactive metabolites, leading to potential therapeutic failure
3. Increased elimination of active, nonmetabolized drug
4. Slowed metabolism of a prodrug into an active drug, leading to an accumulation of prodrug