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Fig. 2 | BMC Cancer

Fig. 2

From: Profound reduction in tamoxifen active metabolite endoxifen in a breast cancer patient treated with rifampin prior to initiation of an anti-TNFα biologic for ulcerative colitis: a case report

Fig. 2

Proposed pathways induced by rifampin resulting in decreased endoxifen levels. Tamoxifen is bioactivated by CYP enzymes to form primary metabolites, NDM-tamoxifen and 4-OH-tamoxifen which are both further converted to the active metabolite endoxifen. Rifampin may lead to the marked reduction in endoxifen levels by (a) shunting tamoxifen metabolism to form alternate metabolites or (b) inducing phase II conjugating enzymes or drug transporters, such as P-glycoprotein, resulting in increased clearance of endoxifen

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BMC Cancer

ISSN: 1471-2407

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