N-Desmethyltamoxifen hydrochloride is the major metabolite of tamoxifen in humans. N-Desmethyltamoxifen, a poor antiestrogen, is a ten-fold more potent protein kinase C (PKC) inhibitor than Tamoxifen. N-Desmethyltamoxifen hydrochloride is also a potent regulator of ceramide metabolism in human AML cells, limiting ceramide glycosylation, hydrolysis, and sphingosine phosphorylation^[1][2][3]. In Vitro: N-desmethyltamoxifen hydrochloride (20-500 ng/ml; 48 hours) has a profound inhibitory effect upon all seven glioma lines (T98G, U87, U138, U373, ALW, AUK, CAS cells)^[1].
N-desmethyltamoxifen hydrochloride (1.5-10 μM; 114 hours) inhibits growth of MCF 7 human mammary carcinoma cells^[2].
N-desmethyltamoxifen hydrochloride, resulting from the CYP3A4/5-mediated catalysis of tamoxifen, is the major primary quantitative metabolite of tamoxifen^[3].