<qa>  What is the effect of inhibiting osteoclasts?Hyperphosphatemia is frequently seen in patients with end-stage renal disease ESRD. Hyperphosphatemia usually results in a high calcium-phosphorus product CPP which may subsequently lead to artery and become a risk factor of cardiovascular complications. Alendronate, due to its effect of inhibiting osteoclasts, is approved for treatment of osteoporosis. Previous reports found the use of bisphosphonates could suppress arterial calcification in hemodialysis dialysis patients. The aim of this study is to evaluate the safety and efficacy of alendronate to suppress coronary artery and aortic calcifications, as well as to improve bone density in chronic peritoneal dialysis PD patients. 