Impact of curcumin with and without (+/-) piperine on tamoxifen exposure.

2572Background: Tamoxifen is extensively used as endocrine therapy for breast cancer. It is a prodrug that is primarily metabolized by CYP2D6 and CYP3A4, particular into endoxifen. In daily practice, the herb curcumin is widely used among patients (pts) because of its presumed anti-tumor effects. Preclinical studies show effects of curcumin on phase I and II drug metabolism, leading to altered plasma levels. We hypothesized that curcumin increases endoxifen exposure by affecting phase II metabolism. Therefore, we performed a randomized, 3-phase, cross-over study to compare tamoxifen exposure in breast cancer pts +/- curcumin, and with the addition of the bioenhancer piperine. Methods: Pharmacokinetic sampling (PK) was performed in 15 pts at the 28th, 56th and 84th day of the trial. In the 28 days prior to PK, tamoxifen (20 mg qd) was either given alone, or combined with curcumin (1,200 mg TID), or with curcumin + piperine (10mg TID) in this order or vice versa. Genotyping was performed to determine CYP2D6...