The Effect of Undaria pinnatifida Fucoidan on thePharmacokinetics of Letrozole and Tamoxifen in Patients With BreastCancer

摘要

>Background: Although the use of complementary and alternative medicines is widespread in cancer patients, clinical evidence of their benefits is sparse. Furthermore, while they are often assumed to be safe with regard to concurrent use of anticancer therapies, few studies have been carried out to investigate possible interactions. Fucoidans are a group of sulfated carbohydrates, derived from marine brown algae, which have long been used as dietary supplements due to their reported medicinal properties, including anticancer activity. The aim of this study was to investigate the effect of co-administration of fucoidan, derived from Undaria pinnatifida, on the pharmacokinetics of 2 commonly used hormonal therapies, letrozole and tamoxifen, in patients with breast cancer. >Methods: This was an open label non-crossover study in patients with active malignancy taking letrozole or tamoxifen (n = 10 for each group). Patients took oral fucoidan, given in the form of Maritech extract, for a 3-week period (500 mg twice daily). Trough plasma concentrations of letrozole, tamoxifen, 4-hydroxytamoxifen, and endoxifen were measured using HPLC-CAD (high-performance liquid chromatography charged aerosol detector), at baselineand after concomitant administration with fucoidan. >Results: Nosignificant changes in steady-state plasma concentrations of letrozole,tamoxifen, or tamoxifen metabolites were detected after co-administration withfucoidan. In addition, no adverse effects of fucoidan were reported, andtoxicity monitoring showed no significant differences in all parameters measuredover the study period. >Conclusions: Administration ofUndaria pinnatifida fucoidan had no significant effect onthe steady-state trough concentrations of letrozole or tamoxifen and was welltolerated. These results suggest that fucoidan in the studied form and dosagecould be taken concomitantly with letrozole and tamoxifen without the risk ofclinically significant interactions.