Efficacy and Safety Study of Cinacalcet for the Treatment of Hypercalcemia in Patients With Primary Hyperparathyroidism Unable to Undergo Parathyroidectomy

Inclusion Criteria: * age ≥ 18 years * diagnosis of primary hyperparathyroidism (HPT) * subjects must have the following laboratory values: 1. local/historical laboratory result showing a corrected total serum calcium \> 1 mg/dL (0.25 mmol/L) above the upper limit of normal and ≤ 12.5 mg/dL (3.12 mmol/L) within the past 12 months, and * local/historical laboratory result showing a plasma parathyroid horone (PTH) \> 75% of upper limit of normal within the past 12 months, and * one central laboratory draw at the screen visit showing a corrected total serum calcium \> 11.3 mg/dL (2.82 mmol/L) and ≤ 12.5 mg/dL (3.12 mmol/L), and * one central laboratory draw at the screen visit showing a plasma PTH \> 55 pg/mL (5.8 pmol/L) OR 2. two central laboratory draws performed during the screening period at least 7 days apart, showing a * corrected total serum calcium \> 11.3 mg/dL (2.82 mmol/L) and ≤ 12.5 mg/dL (3.12 mmol/L), and * plasma PTH \> 55 pg/mL (5.8 pmol/L) * not able to undergo parathyroidectomy for ≥ 1 of the following reasons: * failed parathyroidectomy * comorbid conditions contraindicating parathyroidectomy * parathyroidectomy not considered appropriate or is not feasible by primary physician and subject * before any study-specific procedure is performed, the appropriate written informed consent must be obtained Exclusion Criteria: * symptoms attributable to hypercalcemia, requiring immediate medical intervention, as judged by the investigator (including acute kidney stone, nausea and vomiting requiring intravenous hydration, confusion, lethargy, stupor, or coma) * unstable medical condition, defined as having been hospitalized within 30 days before the date of informed consent, or otherwise unstable in the judgment of the investigator * administration of drugs that increase serum calcium concentration, including but not limited to thiazide diuretics or lithium * initiated bisphosphonate therapy or changed bisphosphonate dose within 12 weeks before the date of informed consent * current administration of drugs for ventricular arrhythmia * unable to provide informed consent, or is at risk for poor compliance with study procedures * currently enrolled in another investigational device or drug study(s), or completed such study within 30 days before the date of informed consent * known hypersensitivity to or unable to tolerate cinacalcet * received treatment with cinacalcet within 60 days before the date of informed consent * history of seizures or an adjustment of anti-seizure medication within 12 weeks before the date of informed consent * family history or diagnosis a genetic syndrome, such as familial benign hypocalciuric hypercalcemia (FBHH) or multiple endocrine neoplasia type 1 (MEN1) and type 2 (MEN2), where primary HPT is one of the clinical manifestations of familial benign hypocalciuric hypercalcemia (FBHH) * refused to use highly effective contraceptive measures (as determined by the investigator) throughout the study * pregnant or breastfeeding