A Long-Term Safety Extension Trial of Ferric Citrate in Patients With End-Stage Renal Disease (ESRD) on Dialysis

Inclusion Criteria: 1. Males or non-pregnant, non-breast-feeding females who participated in the Safety Assessment Period (SAP), and if eligible, the Efficacy Assessment Period (EAP) of Study KRX-0502-304 2. Willing and able to give informed consent Exclusion Criteria: 1. Subjects on KRX-0502 (ferric citrate) in KRX-0502-304 who were treatment failures in first period 2. Any subject in Study KRX-0502-304 SAP who early terminated from the trial 3. Any subject who participated in Study KRX-0502-304 but declined EAP 4. Actively symptomatic gastrointestinal bleeding or inflammatory bowel disease 5. History of malignancy in the last five years 6. Previous intolerance to KRX-0502 (ferric citrate) 7. Intolerance to oral iron-containing products 8. Absolute requirement for oral iron therapy 9. Absolute requirement for Vitamin C (multivitamins \[Nephrocaps, Renaphro, etc.\] allowed) 10. Absolute requirement for calcium-, magnesium-, or aluminum-containing drugs with meals 11. Inability to tolerate oral drug intake 12. Any other medical condition that rendered the subject unable to or unlikely to complete the trial or that would interfere with optimal participation in the trial or produce significant risk to the subject 13. Inability to cooperate with study personnel or history of noncompliance 14. Unsuitable for this trial per Principal Investigator's (PI) clinical judgment.