Repeated-dose Safety, Efficacy, Pharmacokinetic and Pharmacodynamic of CTAP101, Immediate-release Calcifediol, High-dose Cholecalciferol, and Paricalcitol Plus Low-dose Cholecalciferol in Patients With Secondary Hyperparathyroidism, Chronic Kidney Disease 3-4 and Vitamin D Insufficiency

Inclusion criteria

• ✓. Be at least 18 years of age.
• ✓. Have stage 3 or 4 CKD (estimated glomerular filtration rate \[eGFR\] of ≥15 to \<60 millilter per minute per 1.73 meter square (mL/min/1.73 m2) using the Modification of Diet in Renal Disease equation).
• ✓. Be without any disease state or physical condition that might impair evaluation of safety and efficacy or which, in the Investigator's opinion, would interfere with study participation, including:
• ✓. Serum albumin ≤ 3.0 (grams per deciliter (g/dL);
• ✓. Serum transaminase (alanine transaminase, glutamic pyruvic transaminase, aspartate aminotransferase or glutamic oxaloacetic transaminase) \> 2.5 times the upper limit of normal at screening; and,
• ✓. Urinary albumin excretion ≤3000 microgram per milligram (μg/mg) creatinine.
• ✓. Exhibit during the initial screening visit:
• ✓. Plasma intact parathyroid hormone (iPTH) ≥70 picogram per milliliter (pg/mL) and \<400 pg/mL if receiving calcitriol or other 1α- hydroxylated vitamin D analog (paricalcitol or doxercalciferol); or

Exclusion criteria