Osteoporosis New Zealand

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Medications for the Treatment of Osteoporosis: HRT and SERMS

• Treatment with Hormone Replacement Therapy (HRT) is complex and is no longer recommended as a general strategy for the treatment or prevention of osteoporosis. However, in healthy younger (< 60 years) postmenopausal women, HRT is an effective alternative to bisphosphonates, and lowers the risk of osteoporotic fracture with similar efficacy.
• HRT has been shown to reduce the rate of clinical fracture in postmenopausal women (aged 50-79), not selected for high osteoporotic risk. The Women’s Health Initiative (WHI) found that five years of combined HRT reduced the risk of clinical vertebral fractures and hip fractures by 34% and other osteoporotic fractures by 23%.
• Long-term use of HRT is associated with a range of other effects on health, including cardiovascular disease, stroke, pulmonary emboli and invasive breast cancer. The latter relative risk increase after a mean of 5.6 years use was 24% (2.9% versus 2.3% of women, i.e. an absolute risk increase of 0.6%) with the increase in risk emerging after four years use in the WHI. This increased risk of breast cancer does not apply to oestrogen alone therapy.
• In women with premature menopause or primary ovarian failure, use of Oestrogen Replacement Therapy (ERT) or Combined Hormone Replacement Therapy until average age of menopause should be considered, particularly in those who are demonstrated to have a low bone density/peak bone mass.
• Selective oestrogen receptor modulators (SERMS). This is a class of medications that have oestrogen-like properties and effects on bone and lipids, but anti-oestrogenic or antagonistic effects on breast and mixed effects on other organs, including the uterus.
• They have a role in breast cancer prevention in those at high risk.
• Tamoxifen, a first generation SERM, has been shown to decrease the risk of fractures of spine, hip and wrist by 32% in large breast cancer prevention studies. It is not recommended for the treatment of osteoporosis as it is associated with an increased risk of thromboembolism and endometrial carcinoma.
• Raloxifene is a second generation SERM registered, but currently not funded, for use in New Zealand at this time. It has a similar effect to Tamoxifen on decreasing the risk of breast cancer by 50%. It has a better safety profile with fewer cases of uterine cancer, PE and cataracts reported. Eight year data shows a significant reduction in risk for vertebral fractures. Raloxifene has a similar thromboembolism risk as oestrogen. Raloxifene may have a role in younger postmenopausal women who have an increased risk for breast cancer and have a low bone mass for age at menopause.