A prospective randomized pilot study on intermittent post-dialysis dosing of cinacalcet.

Background: Treatment of secondary hyperparathyroidism (SHPT) is important in management of patients with end-stage renal disease on hemodialysis (HD). Calcimimetic agent, cinacalcet provides an option for control of SHPT in patients who fail traditional therapy. It may not have optimal results in non-compliant patients. To enhance compliance, we evaluated effectiveness of post-dialysis dosing of cinacalcet (group AD) as compared to daily home administration (group D) in a prospective randomized trial of HD patients with refractory SHPT.

Methods: After 2-week run-in phase, patients were randomly assigned to two treatment groups. In group AD (N = 12), patients were administered cinacalcet on the day of dialysis (3 times/week) by dialysis staff, while in control group D (N = 11), cinacalcet was prescribed daily to be taken by patients at home. Intact parathyroid hormone (i-PTH), serum calcium, phosphorus, and alkaline phosphatase were followed for 16 weeks and compared to baseline in both groups. Data were analyzed using between-groups linear regression for repeated measures.

Results: No significant decline in i-PTH occurred in group AD at 16 weeks as compared to a significant drop in group D (p = 0.006). However, subgroup analysis showed effectiveness of post-dialysis dosing in patients with less severe SHPT (p = 0.04).

Conclusion: Although daily dosing overall was more effective for treatment of SHPT, dialysis dosing was effective in patients with less severe SHPT. This warrants a larger study considering the limitations of this pilot trial. In the meantime, dialysis dosing can be considered in non-compliant patients with less severe SHPT.