Four Week, Pharmacodynamic/Pharmacokinetic, Efficacy, and Safety Study of Lunacalcipol (CTA018)

Inclusion Criteria: * Subject must have a body mass index (BMI) between 18 and 35 kg/m2, inclusive. * Prior to study entry, subjects must be undergoing maintenance HD tiw, be in stable condition (ie, on maintenance HD for at least 8 weeks) and be expected to remain on HD for the duration of the study. * Subject must be willing and able to discontinue vitamin D and/or bone metabolism therapy for a minimum 2 week wash-out prior to administration of study drug and through the EOS visit. This includes vitamin D supplements daily dose containing more than 1000 IU of ergocalciferol or cholecalciferol) and analogs (calcitriol, paricalcitol, doxercalciferol), cinacalcet, teriparatide, calcitonin, maintenance glucocorticoids (greater than a prednisone equivalent of 5 mg/day), selective estrogen receptor modulators (SERMs; raloxifene or tamoxifen) or other drugs that may affect Ca metabolism. * Subjects must not have taken bisphosphonates for at least 3 months (90 days) prior to the first dose of study drug. * Subject laboratory values must be within the following ranges: * Plasma iPTH ≥350 pg/mL (35 pmol/L) and \<1000 pg/mL (100 pmol/L) * Total serum Ca ≥8.4 mg/dL (2.1 mmol/L) and \<10.0 mg/dL (2.5 mmol/L) * Serum P ≥2.5 mg/dL (0.8 mmol/L) and \<6.2 mg/dL (2.0 mmol/L) * Total serum 25-hydroxyvitamin D level at screening must be ≥15 ng/mL (37 nmol/L). * Subject must be willing and able to comply with study instructions and commit to all clinic visits for the duration of the stu…