Novel therapeutic options for osteoporosis.

Osteoporosis remains a significant clinical problem despite effective therapies. Many patients cannot or will not take currently available therapies. For this reason, research continues in search of more effective and more tolerable agents. Arzoxifene and TSE-424 are investigational selective estrogen receptor modulators that have been shown to be effective in animal studies and are now in clinical studies. Tibolone is a tissue-specific steroid that is currently used in Europe for the prevention and treatment of osteoporosis. Multiple studies have shown efficacy in improving bone mineral density, but no fracture studies have been conducted to date. Although studies of the effect of isoflavones on bone mineral density have been encouraging, a large multicenter study in Europe recently showed no effect of isoflavones on fractures. The investigational bisphosphonates ibandronate and zoledronic acid may offer the advantage of less frequent dosing. The newly described agent osteoprotegerin has been shown in early studies to inhibit bone turnover. Finally, the issue of efficacy of statins in bone continues to be debated with no prospective, randomized studies yet to confirm the suggestion of benefit seen in epidemiologic studies.