Hormone replacement and selective estrogen receptor modulators (SERMS) in the prevention and treatment of postmenopausal osteoporosis

Abstract

For many years, hormone replacement therapy (HRT) has been regarded as one of the most reliable means of prophylaxis and treatment for postmenopausal osteoporosis. As HRT ameliorates menopausal symptoms, it is widely prescribed among early postmenopausal women. A variety of different modes of replacement that suit each individual requirement are available in terms of schedule (cyclic or combined application of gestagens) and route of application (oral or transdermal). HRT effectively prevents spinal bone loss and delays bone loss at the hip up to a very old age. With continued use after menopause, HRT might theoretically halve the incidence of vertebral and hip fractures. However, long-term use or use of HRT in old age is rarely practiced, and the actual benefit of a transient use for future fracture prevention remains unclear. Raloxifene is the first member of the novel class of selective estrogen receptor modulators (SERMs) that has been approved for the prophylaxis and treatment of postmenopausal osteoporosis. It combines the positive effects of estrogen on the skeleton with estrogen-antagonistic effects on sex tissues. Thus, raloxifene maintains bone mass and decreases the incidence of vertebral fractures in osteoporotic women, but avoids many of the side effects that are responsible for the poor long-term compliance to HRT such as resumption or continuation of regular menses, breast tenderness, or breast cancer. It even markedly reduces the risk of breast cancer. Both estrogen and raloxifene are characterized by a large number of extraskeletal effects that have to be taken into account when counseling postmenopausal women on the use of these agents for the prevention or treatment of osteoporosis.