This study will evaluate the effectiveness of alendronate in treating the bone abnormality in polyostotic fibrous dysplasia and McCune-Albright syndrome. In these diseases, areas of normal bone are replaced with a fibrous growth similar to a scar. The weakened bone causes pain and increases patients' risk of bone fractures and bone deformities. Alendronate belongs to a class of drugs called "bisphosphonates," which are approved by the Food and Drug Administration to treat bone weakening, deformity and pain in other medical conditions. It is thought that bisphosphonates might work by slowing the activity of osteoclasts-cells that break down bone. Patients 12 years of age and older with polyostotic fibrous dysplasia or McCune-Albright syndrome may be eligible for this 3-year study. Candidates must also be enrolled in NIDCR's protocol 98-D-0145 (Screening and Natural History of Patients with Polyostotic Fibrous Dysplasia and McCune-Albright Syndrome). Participants will be randomly assigned to one of two treatment groups: they will take one capsule a day of either alendronate or placebo (a look-alike capsule that has no active ingredient). They will take the capsules for 6 months, stop for 6 months, then take them for another 6 months and then go off them for 6 months. They will then remain off the drug or placebo for an additional 12 months and complete the study with a final follow-up visit at 36 months. While taking alendronate or placebo, patients will also take calcium and vitamin D to prevent secondary hyperparathyroidism-a side effect of alendronate in which the bone does not release enough calcium. Patients will come to NIH for a physical examination and blood and urine tests every 6 months and for monitoring of their bone disease, vision, hearing, pain levels, functional evaluation, and photographs every 12 months. Many of the monitoring procedures, including imaging studies and biopsies, are performed for the screening protocol (98-D-0145) and will not be duplicated for this study. During the study periods when patients are taking alendronate or placebo, they will have blood samples drawn by their local physician once every 3 months and sent to NIH to check for secondary hyperparathyroidism. If at the end of the study alendronate is found to be effective, patients who were in the placebo treatment group will be offered alendronate for a 24-month period.
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