Merck osteoporosis drug builds bone density in mid-stage trial By Ransdell Pierson Sat Oct 13, 2012 12:26pm EDT (Reuters) - Hip and spine bone mineral density increased significantly among post-menopausal women on Merck & Co's experimental new osteoporosis drug who had previously taken a standard older company treatment, the drugmaker said on Saturday. The favorable results were seen in a mid-stage trial of Merck's odanacatib, a once-weekly pill which works by blocking an enzyme called cat-K found within bone cells. The enzyme plays a key role in the body's natural process of dissolving bone tissue. The study involved 243 women with osteoporosis who had previously been treated for at least three years with alendronate, the chemical name of Merck's Fosamax drug. It belongs to an older class of medicines called bisphosphonates whose sales have been hurt by rare reports of leg fractures and deterioration of jaw bone in patients taking them. "Odanacatib may be a viable alternative for patients who need continued therapy and who want benefits beyond what they received from bisphosphonates," senior Merck research executive Albert Leung said in an interview, referring to favorable data from the new trial. Patients were given 50-milligram weekly doses of odanacatib, or a placebo, for 24 months. All patients also received vitamin D3 and calcium supplements, if needed. At the end of the study, bone mineral density was shown to increase by a statistically significant degree at three pre-specified hip sites, including a 0.83 percent increase for the total hip. That compared with a 1.87 percent decline in bone mineral density for the total hip among patients receiving placebos. Bone mineral density increased by 2.28 percent at the lumbar spine among those taking odanacatib, compared with a 0.3 percent decrease for patients on placebos. There was no difference between the odanacatib and placebo groups in changes of bone mineral density in the forearm. The overall incidence of side effects were similar between the two treatment groups. Reporting By Ransdell Pierson; Editing by Tim Dobbyn