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The calcimimetic AMG 073 reduces parathyroid hormone and calcium x phosphorus in secondary hyperparathyroidism
Jill S Lindberg1, Sharon M Moe, William G Goodman
1Ochsner Clinical Research Center, New Orleans, Louisiana 70121, USA. jlindberg@ochsner.org
Background:
A need exists for a therapy that lowers parathyroid hormone (PTH) without increasing calcium x phosphorus in patients with secondary hyperparathyroidism. The calcimimetic AMG 073 increases the sensitivity of the parathyroid calcium-sensing receptor to extracellular calcium, thereby reducing PTH secretion. Consequently, AMG 073 may provide a novel therapy for secondary hyperparathyroidism.
Methods:
Seventy-eight hemodialysis patients with secondary hyperparathyroidism were enrolled into this 18-week, double-blind, randomized, placebo-controlled, dose titration study. Daily oral AMG 073 doses were administered to determine the effect on PTH, serum calcium, phosphorus, and calcium x phosphorus.
Results:
The mean baseline PTH was similar in patients administered AMG 073 or placebo (632 +/- 280.1 pg/mL vs. 637 +/- 455.9 pg/mL, respectively). PTH decreased by 26.0% in the AMG 073-treated group, compared with an increase of 22.0% in the placebo group (P < 0.001). A greater proportion in the AMG 073 group (38%) had a decrease in PTH >or=30%, compared with the placebo group (8%) (P = 0.001). Decreases in PTH were independent of baseline vitamin D usage. Patients receiving AMG 073 had an 11.9% decrease in calcium x phosphorus compared with a 10.9% increase in the placebo group (P < 0.001). Use of vitamin D sterols, as well as both calcium and noncalcium-containing phosphate binders. were similar between treatment groups. Administration of AMG 073 was safe and well tolerated in this 18-week study.
Conclusions:
The calcimimetic AMG 073 decreases both PTH and calcium x phosphorus levels in hemodialysis patients with secondary hyperparathyroidism.