The effect of intraperitoneal 22-oxacalcitriol on secondary hyperparathyroidism in continuous ambulatory peritoneal dialysis patients (IPOX study).

Secondary hyperparathyroidism is a major complication in uremic patients undergoing dialysis. Various active metabolites of vitamin D are used as oral treatment; however, in some patients, parathyroid hormone (PTH) is not ideally suppressed. Intravenous injection of an active form of vitamin D inhibits PTH more effectively than does oral administration. However, intravenous administration is often restricted by the complication of hypercalcemia. In the calcitriol analog 22-oxacalcitriol (OCT), the 22nd carbon atom is replaced by oxygen. The OCT analog has been reported to have a lesser hypercalcemic effect than does calcitriol. The present study was planned to determine whether intraperitoneal administration of OCT would be a more effective treatment of secondary hyperparathyroidism than intravenous administration is in CAPD patients who manage themselves at home. The results showed that OCT is stable in dialysis solution and that its intraperitoneal administration was effective for suppressing PTH in patients with secondary hyperparathyroidism.