Sevelamer is primarily used in the treatment of hyperphosphatemia, a condition commonly associated with chronic kidney disease (CKD). It works by binding to phosphate in the digestive tract, preventing its absorption into the bloodstream. This helps to lower and control phosphate levels in patients with CKD, particularly those on dialysis. By managing phosphate levels, sevelamer reduces the risk of complications such as bone disorders and cardiovascular issues, which are often linked to elevated phosphate in CKD patients. Additionally, it is sometimes preferred over other phosphate binders because it does not contain calcium or aluminum, making it suitable for patients who need to avoid these elements.