Pharmacokinetics of raloxifene and its clinical application

Hormone replacement therapy (HRT) administered to postmenopausal women relieves climacteric symptoms, prevents loss of bone mass, and counteracts the development of coronary artery disease. However, whereas all the benefits associated with HRT are achieved only following long-term therapy, the long-term compliance to the regimen is poor. The most common reasons for discontinuance are uterine bleeding, breast pains, and a fear of breast cancer. Long-term HRT may be associated with an increased risk of breast cancer. Consequently, there is a need for an "ideal estrogen", designed to pinpoint desired target tissues for estrogen, such as the bone and liver, while acting as an antiestrogen in uterus and breast tissues. Raloxifene belongs to a new class of compounds, selective estrogen receptor modulators (SERMs). It binds to and interacts with estrogen receptors, acting as an estrogen agonist in bone and liver, but as an estrogen antagonist in breast and uterus. Therefore, raloxifene represents a potentially important alternative to HRT in postmenopausal women for the prevention and treatment of osteoporosis and cardiovascular disease. Clinical studies regarding the drug's long term benefits are still required.