(Z)-2-[4-(1,2-diphenylbut-1-enyl)phenoxy]-N,N-dimethyl-ethanamine
Absorption：Tamoxifen C max is 40 ng/mL (range, 35 to 45 ng/mL), T max is approximately 5 h after dosing, and steady state is achieved in about 4 wk.
Metabolism：Tamoxifen is extensively metabolized. The major metabolite is N-desmethyl tamoxifen. It is a substrate of CYP450 3A, 2C9, 2D6, and an inhibitor of P-glycoprotein.
Elimination：Tamoxifen t ½ is 5 to 7 days; 65% of a dose is excreted over a 2-wk period, with fecal excretion as the primary route of elimination.
Aminoglutethimide, phenobarbital ：Tamoxifen concentrations may be reduced.
Anastrozole ：Plasma concentrations of anastrozole may be decreased. Do not coadminister.
Bromocriptine ：Tamoxifen concentrations may be increased.
Cytotoxic agents ：Increased risk of thromboembolic events.
Letrozole ：Plasma concentrations may be decreased by tamoxifen, reducing the therapeutic effect.
Rifamycins (eg, rifampin) ：Tamoxifen plasma levels may be reduced, decreasing the antiestrogenic effect.
Warfarin ：Increased hypoprothrombinemic effect.
