Role of raloxifene on platelet metabolism and plasma lipids

This study was performed to understand the metabolic effects of raloxifene, a selective oestrogen receptor modulator, on platelets in healthy non-obese postmenopausal women. The data were compared to untreated subjects.

Platelet nitric oxide activity (NO) and peroxynitrite level, platelet inducible and endothelial nitric oxide synthase expression and plasma lipids were evaluated at baseline and after 12 months of raloxifene or placebo treatment.

A significant increase of platelet NO and reduction of platelet peroxynitrite levels, as well as a decrease of inducible nitric oxide synthase expression, was observed 12 months after raloxifene therapy as compared to baseline or placebo treatment. Moreover, raloxifene treatment caused a significant increase in high-density lipoprotein cholesterol and a decrease of total cholesterol and low-density lipoprotein cholesterol were observed versus baseline values (P < 0.05). A significant positive correlation was observed between high-density lipoprotein cholesterol and platelet NO (r = 0.76, P < 0.005) in the raloxifene group.

Our results showed that raloxifene improves platelet metabolism in healthy postmenopausal women through an increase of the bioavailability of platelet NO by a reduction of iNOS and the beneficial effects on lipid metabolism. This mechanism of action of raloxifene on platelet activity may explain some cardiovascular protective effects of this selective oestrogen receptor modulator.