The purpose of this study is to evaluate the superiority of ZG-801 to placebo in Japanese hyperkalemia patients whose serum potassium value becomes normal in the Run-in period by comparing the change in the value at the Double-blind period week 4, and to further evaluate the efficacy and safety of ZG-801 in Japanese hyperkalemia patients administrated ZG-801 for maximum 9 weeks.

Inclusion Criteria:

• Patients whose serum potassium value (local) at the Run-in period baseline is ≥5.5mEq/L, < 6.5 mEq/L
• Age 20 - 80 years old at informed consent
• Patients who understand an overview of the study and voluntarily consented to participate in the study by documents.

Main Exclusion Criteria:

• Patients determined to require emergency treatment for hyperkalemia at the Run-in period baseline

• Patients with poorly controlled blood pressure

• Patients with heart failure in New York Heart Association Class IV

• Patients who have experienced heart transplant, liver transplant or kidney transplant or who are predicted that the need for them will occur during the study

• Patients who have taken any of the following medication within 7 days prior to the Run-in period baseline or currently administrated.

  1. Sodium polystyrene sulfonate
  2. Calcium polystyrene sulfonate
  3. Sodium zirconium cyclosilicate hydrate
  4. Potassium supplement

• Patients with or who have experienced a severe swallowing disorder, moderate to severe gastroparesis, severe constipation, bowel obstruction, incarceration, abnormal post-operative bowel motility disorders or severe gastrointestinal disorders. In addition, patients who have experienced bariatric surgery or major gastrointestinal surgery (e.g., bowel resection).

• Patients suspected to be with transient high potassium value.(ex. caused by dietary effects only)