ANTIESTROGENS AND BONE

Anti-oestrogens are a class of non-steroid compounds with, depending o n the tissue, oestrogen-antagonist or oestrogen-agonist actions result ing from different mechanisms, especially by binding to oestrogen rece ptors. These compounds are commonly called anti-oestrogens because of their extensive use in treating breast cancer. Tamoxifen, the first of these complex compounds, has a partial agonist effect on the endometr ium and also affects bone and lipid metabolism. Currently, our knowled ge of anti-oestrogen action on bone is based on experimental work and a few clinical trials with tamoxifen. The animal studies show that tam oxifen has a preventive effect against bone hyper-remodelling resultin g form ovariectomy in the rat. Most of the clinical studies, including the most recent, show that tamoxifen has no deleterious effect, and p ossibly even a moderate protective effect against bone loss, in menopa used women. This effect on bone tissue, together with lowered plasma c holesterol levels, has led to the development of other compounds with a bone and lipid agonist effect and secondary effects limited to endom etrial hyperplasia. Third generation compounds include droloxifen keox ifen (or raloxifen) currently under investigation. This research shoul d lead to wider indications for anti-oestrogens in the prevention of t he effects of post-menopause oestrogen deficiency, particularly in pat ients with contraindications for oestrogen therapy.