Men's Osteoporosis Support GroupDenosumab to transition from alendronate J Bone Miner Res. 2009 Jul 13. [Epub ahead of print]. Effects of Denosumab on Bone Mineral Density and Bone Turnover in Postmenopausal Women Transitioning from Alendronate Therapy. Kendler DL and others. PMID: 19594293. Denosumab binds to RANKL and is a potent inhibitor of bone resorption. For more information on the mechanism of action of denosumab see this Update. This study involved 504 postmenopausal women who were given 70 mg alendronate (Fosamax) once-weekly tablets for one month. They then either continued with the alendronate or 60 mg denosumab injections every six months for one year. The final outcome was evaluated via changes in bone mineral density (BMD) and biochemical markers of bone turnover. The denosumab showed significantly increased gains in BMD compared to alendronate at the lumbar spine, total hip, femoral neck and 1/3 radius. Median serum CTX levels were significantly decreased versus alendronate at all time points with denosumab. There was no difference in adverse events between the two regimens. The authors concluded, "Transition to denosumab produced greater increases in BMD at all measured skeletal sites and a greater reduction in bone turnover than did continued alendronate, with a similar safety profile in both groups." Editor's comments. Presumably the reason for this study is to show that denosumab will be effective in those who stop taking alendronate, or one of the other bisphosphonates, because they want to continue their therapy with denosumab. The one-month duration of alendronate therapy seems rather short to me, but at least it does indicate that after a brief period of taking alendronate the denosumab produces significantly increased BMD after one year of denosumab compared to one year of alendronate. Future studies showing the same effectiveness in individuals who have taken alendronate for several years would be helpful and informative. Hopefully those are forthcoming. A recent Update of two review articles on denosumab showed conflicting results, particularly concerning reduction of fracture risk and the risk of serious adverse events with denosumab. So there is still some question about the effectiveness and safety of denosumab. And it has not yet received FDA approval, so it is not currently available in the United States. Most results appear positive and the twice yearly 60 mg injection would be convenient if it finally gets final FDA approval. I'll continue to monitor its progress through the system.
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