Fig. 1.

General schematic of the PK study. Eligible patients who met the criteria set for SV1 proceeded to SV2 and discontinued their active vitamin D and cinacalcet, if applicable, and underwent a drug washout period. Subjects entered the treatment phase if serum values at SV3 were as follows: iPTH ≥300 pg/mL, albumin-corrected serum calcium ≤9.8 mg/dL and phosphorus ≤6.5 mg/dL. PK plasma samples were collected after the first dose and before the last dose and at various times after that dose. The treatment period lasted 4 weeks, with the first and final visits scheduled to occur on the same day of the week. Additional blood samples were collected at 4, 12 and 48 h after the final dose for analysis of iPTH, corrected calcium, and phosphorus. iPTH intact parathyroid hormone, PK pharmacokinetic, SV screening visit, VDRA vitamin D receptor activator, wk week