Double-blind study comparing doxercalciferol and placebo in vitamin D-replete CKD patients

OBJECTIVE

No well-controlled studies of the safety and efficacy of active vitamin D analogues have been conducted in vitamin D-replete (25-hydroxyvitamin D ≥ 30 ng/mL) patients. This study assessed the safety and efficacy of doxercalciferol in vitamin D-replete patients with secondary hyperparathyroidism.

METHODS

This was a randomized, double-blind, placebo-controlled, parallel study. Twenty-four vitamin D-replete (exogenous ergocalciferol or intrinsically replete) patients with elevated intact parathyroid hormone (iPTH) were randomized to receive doxercalciferol or matching placebo capsules for 24 weeks. The dose was regularly titrated to achieve target iPTH levels (CKD Stage 3: ≤ 70 pg/mL; CKD Stage 4: ≤ 110 pg/mL).

RESULTS

Eleven (92%) doxercalciferol patients met the iPTH target range at least once post randomization compared with four (33%) placebo patients. All 12 (100%) doxercalciferol patients achieved a 30% reduction in iPTH at least once post randomization, and more doxercalciferol patients (83%) maintained iPTH within the target range for up to 6 weeks compared with the placebo patients (17%). Doxercalciferol and placebo were well tolerated during the study. No adverse events of hypercalcemia were reported.

CONCLUSIONS

Doxercalciferol was well tolerated and effective in reducing iPTH in vitamin D-replete CKD patients without accompanying hypercalcemia. Further studies in a larger population of vitamin D-replete patients are needed.