Summary
Tamoxifen is a known anti-cancer drug and established estrogen receptor modulator.
Few clinical studies have earlier implicated the drug in thrombotic complications
attributable to lower anti-thrombin and protein S levels in plasma. However, action
of tamoxifen on platelet signalling machinery has not been elucidated in detail. In
the present report we show that tamoxifen is endowed with significant inhibitory property
against human platelet aggregation. From a series of in vivo and in vitro studies tamoxifen was found to inhibit almost all platelet functions, prolong tail
bleeding time in mouse and profoundly prevent thrombus formation at injured arterial
wall in mice, as well as on collagen matrix perfused with platelet-rich plasma under
arterial shear against the vehicle dimethylsulfoxide (DMSO). These findings strongly
suggest that tamoxifen significantly downregulates platelet responses and holds potential
as a promising anti-platelet / anti-thrombotic agent.
Keywords
Antiplatelet drug - estrogen receptor - platelet aggregation - selective estrogen
receptor modulators (SERM) - thrombosis