Clin Drug Invest 2006; 26 (2): 63-74 ORIGINAL RESEARCH ARTICLE 1173-2563/06/0002-0063/$39.95/0 © 2006 Adis Data Information BV. All rights reserved. Alendronic Acid Produces Greater Effects than Risedronic Acid on Bone Density and Turnover in Postmenopausal Women with Osteoporosis Results of FACTS 1 -International David M. Reid, 1 David Hosking, 2 David Kendler, 3 Maria L. Brandi, 4 John D. Wark, 5 Georges Weryha, 6 Jo˜ ao F. Marques-Neto, 7 Keavy A. Gaines, 8 Nadia Verbruggen 8 and Mary E. Melton 8 1 Department of Medicine and Therapeutics, University of Aberdeen, Aberdeen, UK 2 Department of Bone and Mineral Metabolism, Nottingham City Hospital, Nottingham, UK 3 Clinical Research Centre, St Vincent’s Hospital, Vancouver, British Columbia, Canada 4 Department of Medicine, University of Florence, Florence, Italy 5 Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia 6 Service d’Endocrinologie, H ˆ opital de Brabois, Nancy, France 7 Department of Rheumatology, State University (Unicamp), Campinas, S˜ ao Paulo, Brazil 8 Merck & Co., Inc., Whitehouse Station, New Jersey, USA Background: The objective of the study was to evaluate the effects of alendronic Abstract acid once weekly relative to risedronic acid once weekly on bone mineral density (BMD), markers of bone turnover and tolerability in the treatment of osteoporosis in postmenopausal women. Methods: This was a randomised, double-masked, double-dummy multicentre international study (75 centres in 27 countries in Europe, the Americas and Asia-Pacific). A total of 1303 women were screened and 936 with low bone density (T-score ≤–2.0 at the spine, hip trochanter, total hip or femoral neck) were randomised; 91% (n = 854) completed the study. Patients were randomised to treatment with either active alendronic acid 70mg weekly (Fosamax ® ) and placebo identical to risedronic acid weekly or active risedronic acid 35mg weekly (Actonel ® ) and placebo identical to alendronic acid weekly for 12 months. The primary efficacy endpoint was the percentage change from baseline in hip trochanter BMD at 12 months. Secondary endpoints included the percentage change from baseline in lumbar spine, total hip and femoral neck BMD; biochem- ical markers of bone turnover (including serum bone-specific alkaline phospha- 1 Fosamax Actonel Comparison Trials.