Evaluation of CYP2D6 enzyme activity using a 13C-dextromethorphan breath test in women receiving adjuvant tamoxifen.

ABSTRACT:

Background

In tamoxifen-treated patients, breast cancer recurrence differs according to CYP2D6 genotype and endoxifen steady-state concentrations (Endx Css). The ¹³C-dextromethorphan breath test (DM-BT), labeled with ¹³C at the O-CH3 moiety, measures CYP2D6 enzyme activity. We sought to examine the ability of the DM-BT to identify known CYP2D6 genotypic poor metabolizers and examine the correlation between DM-BT and Endx Css.

Methods

DM-BT and tamoxifen pharmacokinetics were obtained at baseline, 3, and 6 months following tamoxifen initiation. Potent CYP2D6 inhibitors were prohibited. The correlation between baseline DM-BT with CYP2D6 genotype and Endx Css was determined. The association between baseline DM-BT (where values ≤0.9 is an indicator of poor in vivo CYP2D6 metabol

SUBMITTER: Safgren SL 

PROVIDER: S-EPMC4356640 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature