Study designs. Study design of healthy volunteers treated with patiromer showing controlled diet and urine collection periods in the (A) dose-finding and (B) dose regimen studies. BID, two times per day; BMI, body mass index; Ca, calcium; K, potassium; Mg, magnesium; Na, sodium; P, phosphate; QD, daily; R, date of randomization; TID, three times per day.