Tamoxifen-d3 hydrochloride is a deuterium-labeled derivative of Tamoxifen (Citrate), which is an orally active selective estrogen receptor modulator (SERM). It inhibits estrogen activity in breast cells while activating estrogen receptors in other cells such as those in bone, liver, and uterus. Tamoxifen Citrate acts as a potent Hsp90 activator, enhancing the ATPase activity of the Hsp90 molecular chaperone. Furthermore, it effectively suppresses infectious EBOV Zaire and Marburg (MARV) viruses with IC50 values of 0.1 μM and 1.8 μM, respectively. Tamoxifen Citrate also stimulates autophagy and induces apoptosis, and is capable of triggering gene knockout in CreER(T2) transgenic mice.