DENOSUMAB (Xgeva, Prolia)
Denosumab, marketed by AMGEN as Xgeva and Prolia, is a monoclonal antibody that inhibits RANKL, a molecule decisive in the formation of osteoclasts (the cells that “eat” bone). Denosumab role in the spectrum of osteoporosis therapies remains to be established. There is not evidence that denosumab will be more efficacious than other better known agents . Neither there is lack of information regarding denosumab long-term safety. Until those data will be availaible, it seems reasonable to use denosumab as second-line therapy for those patients unresponsive or intolerant to other therapies. Denosumab is injected subcutaneously twice yearly and, overall, is well tolerated. More frequent adverse effects are musculo-skeletal pain, fatigue, weakness and hypophosphatemia.
Suggested readings: N Engl J Med. 2009 Aug 20; 361(8): 818-20. Curr Opin Rheumatol. 2009 Jul; 21(4):369-73
BAZEDOXIFEN (Viviant, Conbriza)
Bazedoxifen is a third generation of Selective Estrogen-Receptor Modulators(SERM) sold by PFIZER under the tradename Viviant in the US and Conbriza in Europe. SERM are a class of compounds that act on the estrogen receptor but, by contrast from pure receptor agonists and antagonists, SERM’s action is different in various tissues, thereby granting the possibility to selectively inhibit or stimulate estrogen-like action in various tissues. Thus, it was specifically designed to simultaneously prevent breast cancer and bone fractures by treating osteoporotic patients. Bazedoxifen 20 mg once daily increases bone density a reduces risk of vertebral fractures. Overall is well tolerated. However, as other SERM, bazedoxifen has an increased risk of deep venous thrombosis. Bazedoxifene may be an appropriate therapy for women who cannot take bisphosphonates or younger women at increased fracture risk who are concerned about the effects of long-term bisphosphonate therapy.
Suggested readings: J Bone Miner Res. 2011 Mar;26(3):519-29. Osteoporos Int. 2012 Jan;23(1):351-63