Evaluates the effectiveness of on-label Paricalcitol versus Cinacalcet with Low-Dose Vitamin D.

During a 4-week washout period, participants stopped taking cinacalcet or other vitamin D receptor activators (VDRAs). (Participants who were naive to cinacalcet or VDRAs did not have to wash out). At randomization, participants entered a 28-week open-label treatment period, during which they received either cinacalcet or paricalcitol. Participants who were assigned to receive paricalcitol were dosed according to the approved label in their respective geographic regions (i.e., IV at sites in the US and Russia and oral at sites in Europe). Supplemental cinacalcet was administered to participants in the paricalcitol arms who developed hypercalcemia (defined as >= 10.5 mg/dL). The evaluation period was from Weeks 21 to 28.

Inclusion Criteria

1. Male or female patients >= 18 years old.

2. Patient was diagnosed with Stage 5 chronic kidney disease (CKD) and had been receiving intravenous (IV) or oral vitamin D receptor activators (VDRAs) or cinacalcet during the 8 weeks prior to the screening period or naïve patients who had not received VDRA or cinacalcet within 8 weeks of screening.

3. Patient was on maintenance HD (hemodialysis) 3 times weekly (TIW) for at least 3 months prior to screening and was expected to remain on HD for the duration of the study.

4. For entry into the Pre-Treatment Washout Period (for patients who were not naïve to VDRAs and cinacalcet), the patient had to have screening laboratory values of:

   • iPTH level 130 to 700 pg/mL
   • Serum Total Alkaline Phosphatase level >= 40 U/L
   • Calcium level <= 10.0 mg/dL (2.49 mmol/L)
   • Calcium-phosphorus product (CaxP) <= 75 mg2/dL2 (US) and <= 70 mg2/dL2 (non-US)

Exclusion Criteria

1. Patient had a history of parathyroidectomy.
2. Patient had a current malignancy (with the exception of basal or squamous cell carcinoma of the skin), or clinically significant liver disease, in the opinion of the investigator.
3. Use of known inhibitors (i.e., ketoconazole) or inducers (i.e., carbamazepine) of cytochrome P450 (including grapefruit and/or grapefruit juice) 3A (CYP3A) or drugs metabolized by cytochrome P450 2D6 (CYP2D6) (e.g., flecainide, vinblastine, thioridazine, and most tricyclic antidepressants) within 2 weeks prior to study drug administration. Commonly used beta blockers such as metoprolol and carvedilol are allowed but are metabolized by CYP2D6; thus, an adjustment to a lower dose may have been required.
4. Patient was known to be human immunodeficiency (HIV) positive.