Dr Slatopolsky serves as a consultant to Abbott Pharmaceuticals. Dr Plum is the Director of Research and Development for Deltanoid Pharmaceuticals, Inc. Dr Clagett-Dame is the Vice President, co-owner, and Chief Scientific Officer of Deltanoid Pharmaceuticals, Inc. Dr DeLuca is a co-owner and the Chief Executive Officer of Deltanoid Pharmaceuticals, Inc. All other authors state that they have no conflicts of interest.
Article first published online: 5 FEB 2007
Copyright © 2007 ASBMR
Journal of Bone and Mineral Research
Volume 22, Issue 5, pages 686–694, May 2007
How to Cite
Slatopolsky, E., Finch, J. L., Brown, A. J., Ritter, C. S., Mizobuchi, M., Plum, L. A., Clagett-Dame, M., Sicinski, R. R. and DeLuca, H. F. (2007), Effect of 2-Methylene-19-nor-(20S)-1α-Hydroxy-Bishomopregnacalciferol (2MbisP), an Analog of Vitamin D, on Secondary Hyperparathyroidism. J Bone Miner Res, 22: 686–694. doi: 10.1359/jbmr.070202
Published online on February 5, 2007
- Issue published online: 4 DEC 2009
- Article first published online: 5 FEB 2007
- Manuscript Accepted: 1 FEB 2007
- Manuscript Revised: 7 DEC 2006
- Manuscript Received: 13 JUL 2006
- vitamin D;
- secondary hyperparathyroidism;
Vitamin D analogs are being developed that retain therapeutic effects but are less calcemic and phosphatemic, a concern in CKD patients who are prone to vascular calcification. We tested a new analog of vitamin D, 2MbisP, and found that it suppresses PTH at doses that do not affect serum Ca or P.
Introduction: Calcitriol is used for the treatment of secondary hyperparathyroidism. However, its use is often limited by the development of hypercalcemia and hyperphosphatemia, an important consideration in patients with chronic kidney disease (CKD) because they are prone to vascular calcification. To minimize this toxicity, structural modifications in the vitamin D molecule have led to the development of calcitriol analogs with selective actions.
Materials and Methods: In this study, we compared the effects of 1,25(OH)2D3 and a new analog, 2-methylene-19-nor-(20S)-1α-hydroxy-bishomopregnacalciferol (2MbisP), on the development of secondary hyperparathyroidism and established secondary hyperparathyroidism in uremic rats and on mobilization of calcium and phosphorus from bone in parathyroidectomized rats. The clearance from circulation, half-life, and binding affinities to the vitamin D–binding protein and vitamin D receptor of this compound were also evaluated.
Results: Uremia produced a marked rise in plasma PTH, but treatment every other day for 2 wk with either 1,25(OH)2D3 (4 ng) or 2MbisP (250, 750, 1500, or 3000 ng) suppressed this increase by >50%. The suppression by 1,25(OH)2D3, however, was accompanied by increases in ionized calcium, phosphorus, and the calcium × phosphorus product, whereas these three parameters were unchanged by 2MbisP. The binding affinity of 2MbisP was 10–20 times less for the vitamin D receptor and 1000 times less for the serum vitamin D–binding protein compared with 1,25(OH)2D3. Also, 2MbisP was cleared more rapidly from the circulation (t½ = 10 min) than 1,25-(OH)2D3 (t½=7–9 h). In parathyroidectomized rats fed calcium-or phosphorus-deficient diets, daily injections of 2MbisP (1500 or 3000 ng), unlike 1,25(OH)2D3 (50 ng), had no effect on calcium or phosphorus mobilization from bone.
Conclusions: In uremic rats, 2MbisP can suppress PTH at doses that do not affect plasma calcium, phosphorus, and calcium × phosphorus product. This new vitamin D analog may represent an important tool in the treatment of secondary hyperparathyroidism in patients with CKD.