Patients with chronic kidney disease who were receiving RAAS inhibitors and who had serum potassium levels of 5.1 to less than 6.5 mmol per liter received patiromer ( at an initial dose of 4.2 g or 8.4 g twice a day ) for 4 weeks ( initial treatment phase ) ; the primary efficacy end point was the mean change in the serum potassium level from baseline to week 4 .