Comparison of the efficacy of two injectable forms of vitamin D3 and oral one-alpha in treatment of secondary hyperparathyroidism in patients on maintenance hemodialysis.

ABSTRACT

In the present study, we compared the efficacy of two intravenous forms of vitamin D3[Calcijex 1,25(OH)2D3 and One-Alpha 1(OH)D3] and that of oral One-Alpha in the treatment of secondary hyperparathyroidism in patients receiving maintenance hemodialysis. Twenty patients were assigned to 1 of 2 treatment groups (A and B) which were matched for age, sex, and duration of maintenance hemodialysis. None of the patients included had chronic liver disease or had received drugs known to interfere with hepatic enzymes. All patients had received a stable dose of oral calcium and One-Alpha for a minimum period of 1 year, which maintained corrected serum calcium at the upper limit of the normal range. At the start of the study, oral One-Alpha was replaced by Calcijex in group A and injectable One-Alpha in group B. Treatment was maintained for 3 months (phase I). Subsequently, injectable vitamin D3 was discontinued and all patients received their previous dose of oral One-Alpha for a period of 1 month. Finally, oral One-Alpha was discontinued again and the injectable forms of vitamin D3 were crossed over in the 2 treatment groups for another 3 months (phase II). The results showed that the serum concentrations of 1,25(OH)2D3, measured 48 h after intravenous injection of One-Alpha, were not different from that produced by an equivalent dose of Calcijex in the same group of patients. Furthermore, overall analysis of intact parathyroid levels during the cross-over, using ANOVA with repeated responses, indicated that the two analogues were equipotent as regards suppression of PTH secretion. In our study, treatment with intravenous vitamin D3 led to significant suppression of PTH secretion. These results were achieved by a lower drug dosage of vitamin D3 and at lower trough blood levels of 1,25(OH)2D3 as compared to those of oral One-Alpha. Our findings are in favor of the early use of either forms of injectable vitamin D3 in the treatment of secondary hyperparathyroidism.