Please select the eligibility criteria that correspond to the clinical trial below.
Title: An Open-label, Randomised, Active-controlled, Parallel Group, Multicentre, Phase 3 Study to Investigate the Safety and Efficacy of PA21 Compared With Sevelamer Carbonate Followed by a Randomised Comparison of PA21 Maintenance Dose Versus PA21-Low Dose in Dialysis Patients With Hyperphosphataemia
Brief Summary: This is a Phase 3, randomised, active controlled, multicentre study to investigate the safety and efficacy of PA21, a phosphate binder, for control of hyperphosphataemia in dialysis patients. The primary objective is to establish the efficacy of PA21 for lowering phosphate levels in these patients.


Options:
A: Inclusion Criteria:

* Dialysis patients with hyperphosphataemia (≥ 1.94 mmol/L; ≥ 6.0 mg/dL)
* Stable dose of phosphate binder
* Written informed consent

Exclusion Criteria:

* Hyper/hypo calcemia; hyper intact parathyroid hormone (iPTH)
* Other significant medical conditions
* Pregnancy
B: Inclusion Criteria:

1. Patients with a GFR of \< 45 ml/min;
2. Intact serum PTH \> 37 pg/ml;
3. Age \> 35 years (both genders and all races);
4. Able to perform two three-week balance studies;
5. Not on oral calcium or vitamin D other than multi vitamin, or willing to stop calcium or vitamin D for one month prior to entry in the study (day 1 of first calcium balance period);
6. Female patients must be post-menopausal (defined as last menstrual period at least 12 months prior to screening visit) or surgically sterile by hysterectomy;
7. On stable doses of diuretics, bisphosphonates, anti-epileptics (except dilantin) for at least 2 months.

Exclusion Criteria:

1. Serious underlying systemic disease (including uncontrolled diabetes, lupus, hypertension, amyloid, etc);
2. Taking drugs that alter calcium and phosphate balance or homeostasis including high dose cholecalciferol or ergocalciferol (1000 U/day or 50,000U/ wk, respectively), active vitamin D metabolites, calcimimetics, PTH analogues in the last 30 days;
3. Taking drugs that the investigator feels will alter calcium balance;
4. Plan to initiate dialysis in the next six months;
5. Hypercalcemia defined as serum calcium \> 10.5 mg/dl;
6. Hyperphosphatemia defined as serum phosphate \>5.5mg/ml;
7. Intestinal disease that alters absorption or normal intestinal function including celiac disease, small bowel resection, bariatric surgery;
8. Smoking
C: Inclusion Criteria:

* incident patients on haemodialysis (CKD stage 5);
* an informed consent will be provided at the study entry.

Exclusion Criteria:

* congenital prolongation of QT segment syndrome;
* QTc \>440 ms; increased QTd;
* bradycardia \<50 bpm;
* sintomatic arrhythmia or any other significant heart problems;
* electrolyte unbalances (especially hypokalemia, hypomagnesemia, hypocalcemia);
* abnormal liver function tests;
* hypothyroidism.
D: Inclusion Criteria:

* Males or non-pregnant, non-lactating females
* Age \> 18 years
* On thrice weekly hemodialysis or peritoneal dialysis for at least the previous three months prior to Screening Visit (Visit 0)
* Serum phosphorus levels ≥ 3.5 mg/dL and \< 8.0 mg/dL at Screening Visit (Visit 0)
* Serum phosphorus levels \> 6.0 mg/dL during the washout period (Visits 2 or 3)
* Taking 3 to 15 tablets/capsules per day of 667mg calcium acetate or 800 mg sevelamer (hydrochloride or carbonate), or any combination of these agents as reported by the patient at Screening Visit (Visit 0)
* Serum ferritin \<1000micrograms/L and Transferrin Saturation (TSAT) \<50% at the Screening Visit (Visit 0)
* Willingness to be discontinued from current phosphate binder(s) and initiated on KRX-0502 (ferric citrate)
* Willing and able to give informed consent
* Willing and able to stay on a constant dose of Vitamin D (or its analogs) and Sensipar (cinacalcet) for the treatment period, if applicable.

Exclusion Criteria:

* Parathyroidectomy within six months prior to Screening Visit (Visit 0)
* Actively symptomatic gastrointestinal bleeding or inflammatory bowel disease
* Serum phosphorus levels \>10.0 mg/dL documented in all of the three monthly laboratories (done routinely in the dialysis unit) in the three months prior to the Screening Visit (Visit 0)
* History of multiple drug allergies or intolerances
* History of malignancy in the last five years (treated cervical or non-melanomatous skin cancer may be permitted if approved by CCC)
* Previous intolerance to oral ferric citrate
* Absolute requirement for oral iron therapy
* Absolute requirement for Vitamin C (multivitamins \[Nephrocaps, Renaphro, etc.\] allowed)
* Absolute requirement for calcium-, magnesium-, or aluminum-containing drugs with meals
* Psychiatric disorder that interferes with the patient's ability to comply with the study protocol
* Inability to tolerate oral drug intake
* Planned surgery or hospitalization during the trial (scheduled outpatient access surgery allowed)
* Any other medical condition that renders the patient unable to or unlikely to complete the trial or that would interfere with optimal participation in the trial or produce significant risk to the patient
* Receipt of any investigational drug within 30 days of Screening Visit (Visit 0)
* Inability to cooperate with study personnel or history of noncompliance
* Unsuitable for this trial per Principal Investigator's clinical judgment

Answer: A