ALENDRONATE TO IMPROVE BONE MINERAL DENSITY IN BOYS W/DUCHENNE MUSCULAR DYSTROPH

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Fractures are a significant source of morbidity in boys with Duchenne muscular dystrophy (DMD), as they not only cause discomfort, but can also precipitate early loss of ambulation (1;2). This is likely related to progressive weakness and subsequent immobility, which has been associated with osteoporosis. Glucocorticoids have been used in the treatment of DMD to slow the progression of weakness and loss of function and have been shown to induce osteoporosis (3). The combination of immobility and glucocorticoid treatment, may, thus predispose these children to fractures resulting from minimal trauma. The use of Dual Energy X-ray Absorptiometry (DXA) has allowed the determination and monitoring of bone mineral density (BMD) in children. DXA scans have shown significantly decreased BMD in boys with Duchenne muscular dystrophy (4;5). Thus, treatment to improve BMD could potentially decrease the risk of fractures and its associated morbidity. The use of bisphosphonate medications in children with osteoporosis improves BMD without significant side effects (6-8). We propose a randomized, double-blinded, placebo controlled study using weekly oral alendronate, a bisphosphonate to improve bone mineral density in boys with Duchenne muscular dystrophy. The control group will receive daily Vitamin D and calcium and a weekly placebo pill. The experimental group will receive these supplements as well as weekly oral alendronate. Bone mineral density will be evaluated at baseline, 6 months, and a year. We hypothesize that the boys receiving alendronate, a bisphosphonate, and oral calcium and vitamin D supplements will have a greater improvement in bone mineral density than boys receiving oral supplements alone.