Protocol HECT00306 aims to determine clinically appropriate doses of Hectorol (doxercalciferol capsules) when converting from Zemplar (paricalcitol injection) for the treatment of secondary hyperparathyroidism in Stage 5 chronic kidney disease on hemodialysis.

Inclusion Criteria:

• The subject must be receiving hemodialysis three times per week for a minimum of six months.
• The subject must have been receiving Zemplar Injection for a minimum of 3 months. The subject must have been on a stable dose regimen, three times per week administration for a minimum of four weeks.
• The central laboratory assessment must be within the following ranges: serum iPTH between 150-600 pg/mL, inclusive; corrected calcium < 10.0 mg/dL; phosphorus < 7.0 mg/dL.

Exclusion Criteria:

• In the opinion of the Investigator, the subject currently has poorly controlled diabetes mellitus, poorly controlled hypertension, active vasculitis, HIV infection, or any other clinically significant, unstable medical condition.
• Abnormal liver function as measured by ALT/AST greater than two times the upper limit of normal (ULN).
• The subject currently has malabsorption, severe chronic diarrhea, or ileostomy.
• Any evidence of active malignancy except for basal cell carcinoma of the skin. A history of malignancy is not an exclusion.