Defining the role of raloxifene as a therapeutic agent for postmenopausal osteoporosis: focus on its pharmacological properties

Abstract

In this semiar, I propose to describe the pharmacological properties of raloxifene that provide a basis for its role in the treatment of postmenopausal osteoporosis. These pharmacological properties can be described as providing therapeutic benefits in the following three areas: 1) reduction in bone turnover, 2) increases in bone mineral density, and 3) risk reduction in fractures. While reloxifene shares these effects with conventional bisphosphonates that are in common use for postmenopausal osteoporosis, it exerts its antiresorptive effects through a different mechanism of action from those of the bisphosphonates. Furthermore, raloxifene exerts its stimulatory or inhibitory effects on estrogen in a tissue-specific fashion as a selective estrogen-receptor-modulator (SERM), thereby providing a wide range of clinical benefits that result from its ability to exert estrogen-like beneficial effects in tissues other than bone while at the same time inhibiting estrogen-like deleterious effects in other tissues. I therefore propose to define the role of raloxifene as a viable therapeutic option in the treatment of postmenopausal osteoporosis in light of these unique pharmacological features. Current data suggests that raloxifene can be positioned somewhere in between hormone replacement therapy (HRT) and bisphosphonates, and is highly likely to be suitable for use in patients between the ages of 55 and 70, while other agents may be indicated in special populations, such as premenopausal patients, postmenopausal patients with hot flushes, or elderly patients who may be placed at accelerated risk of developing femoral neck fractures. Thus, as a novel therapeutic option with unique clinical benefits, a far greater role may be expected for raloxifene in the treatment of postmenopausal osteoporosis than for other conventional therapeutic agents.