Pharmacokinetics and pharmacodynamics of cinacalcet in patients with renal failure receiving hemodialysis and hemodiafiltration therapy

Objective: Few studies have focused on the effects of dialysis on cinacalcet. In addition, there is no data available on hemodiafiltration (HDF) all over the world. Therefore, we studied the pharmacokinetics (PK) and pharmacodynamics (PD) of cinacalcet in patients undergoing hemodialysis (HD) or HDF to provide more guiding information on its use in these patients, especially in China. Materials and methods: In this open-label, single-dose, single-center study of 7 patients with renal failure who underwent dialysis, patients were randomly allocated to two groups consisting of 4 and 3 patients who received low-flux HD and HDF treatments, respectively. All participants underwent dialysis for 4 hours immediately after receiving single oral doses of a 25 mg cinacalcet tablet. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and electrochemical luminescence (EI) were used to determine the cinacalcet plasma concentrations and intact parathyroid hormone (iPTH) serum levels, respectively. Results: Peak concentration (C-max) and area under the curve (AUC) from time 0 to 24 hours (AUC(0-24h)) of the low-flux HD therapy group were 21.8 +/- 18.6 ng/mL and 145.3 +/- 91.8 ngxh/mL, respectively, which were similar to those of the HDF group (30.9 +/- 7.9 ng/mL and 161.6 +/- 26.5 ngxh/mL, respectively). iPTH concentrations of the HD therapy group decreased after cinacalcet administration and increased following its clearance. However, iPTH levels of subjects receiving HDF therapy did not change. Conclusion: Compared with healthy Chinese subjects, patients with renal failure had a higher C-max and AUC(0-24h), slightly prolonged time to C-max (t(max)) after administration of the same dose of cinacalcet. On HD treatment day, variation trends of iPTH in Chinese patients and healthy subjects were similar and significantly different from that on the HDF treatment day. Considering the high protein binding rate of cinacalcet. this may lead to the great free-drug clearance during HDF treatment.