Secondary hyperparathyroidism, a common consequence of chronic kidney disease, results from abnormal regulation of calcium and phosphate homeostasis. The early administration of calcium supplements or vitamin D attenuates the development and progression of hyperparathyroidism, preventing or retarding the emergence of many of the serious complications of chronic kidney disease. However, these vitamin D derivatives also have serious side effects, including hypercalcemia and hyperphosphatemia and, as a result, a high level of the calcium-phosphate product. These adverse outcomes have prompted the development of novel, nonhypercalcemic vitamin D analogues. Three of these analogues have recently been marketed for clinical use in patients with chronic kidney disease: 19-nor-1,25-dihydroxyvitamin D2 (paricalcitol), 1 -hydroxyvitamin D2 (doxercalciferol), and 22-oxacalcitriol.~Oral paricalcitol was developed to provide a convenient, alternative therapy, particularly for Peritoneal Dialysis patients in whom regular intravenous administration of paricalcitol is not practical. This study is designed to determine the proportion of patients with 'End stage renal failure' on haemodialysis or peritoneal dialysis and secondary hyperparathyroidism who achieved more than 30% reduction in baseline iPTH concentration at 24 weeks of treatment with Paricalcitol or Calcitriol capsules.
The purpose of this study is to determine whether oral paricalcitol is safer and more efficacious compared to oral calcitriol in the treatment of hyperparathyroidism in chronic kidney disease patients undergoing dialysis.