Low enrollment rate

The primary objective of this study is to evaluate the efficacy and safety of paricalcitol in participants with moderate to severe secondary hyperparathyroidism (SHPT) undergoing hemodialysis who are resistant to treatment with calcitriol.

This is a multi-center, prospective, open label, one arm, phase IV study designed to demonstrate paricalcitol efficacy and safety in the treatment of moderate to severe secondary hyperparathyroidism in calcitriol resistant participants on dialysis.

Following screening, participants began an 8-week controlled calcitriol therapy period. Participants whose parathyroid hormone (PTH) levels decreased were to be discontinued from the study. Those whose PTH levels did not decrease began paricalcitol therapy using a dose calculated by 0.04 to 0.1 microgram per kilogram (mcg/kg). Paricalcitol was administered intravenously at anytime during the subjects' dialysis. The paricalcitol dose was to be titrated every 2 weeks until iPTH was reduced or up to 4 months, after which it was to be adjusted monthly for 1 year based on serum PTH, calcium, phosphorus, and albumin measurements.

Inclusion Criteria:

• Male and female participants > 18 years of age, with chronic kidney disease (CKD) stage V;
• Participants with diagnosis of calcitriol resistance defined as: Episodes of hypercalcemia and/or hyperphosphatemia (defined as an episode of calcium or phosphorus above Upper Limit of Normal or documented by medical history stating that the treatment with calcitriol was discontinued due to hypercalcemia and/or hyperphosphatemia) that precludes treatment continuation and/or persistent PTH above 600pg/mL during the calcitriol therapy;
• PTH value at screening visit between 600 pg/mL and 2,000 pg/mL;
• Stable clinical conditions;
• Participant has voluntarily consented to participate in the study, by signing and dating an informed consent form, approved by an Institutional Review Board (IRB)/Independent Ethics Committee (IEC), after the nature of the study has been explained and all his questions about the study have been elucidated. The informed consent must be signed before any study-specific procedures are performed.

Exclusion Criteria:

• Previous parathyroidectomy;
• Presence of hypercalcemia (corrected Ca > 10.5 mg/dL) and/or hyperphosphatemia (P > 6.0 mg/dL) and/or Ca x P product > 60, at screening visit (corrected Ca calculated by: [4 - participant's serum albumin (g/dL)] x 0.8 + participant's serum Ca value);
• Severe and/or unstable clinical conditions, e.g., congestive heart failure, advanced cancer, advanced HIV disease, severe endocrinopathies, uncompensated diabetes mellitus, life-threatening cardiac arrhythmias, etc;
• Abnormal liver tests (> 1.5 times above upper limit of normal);
• Pregnant or breast-feeding women;
• Evidence of vitamin D toxicity;
• Known hypersensitivity to any study drug components.

Early termination leading to no efficacy evaluation. All adverse events occurred during calcitriol challenge phase.