indication

For the control of serum phosphorus in patients with Chronic Kidney Disease (CKD) on hemodialysis.

pharmacology

Patients with end-stage renal disease (ESRD) retain phosphorus and can develop hyperphosphatemia. High serum phosphorus can precipitate serum calcium resulting in ectopic calcification. When the product of serum calcium and phosphorus concentrations (Ca x P) exceeds 55 mg²/dL², there is an increased risk that ectopic calcification will occur. Hyperphosphatemia plays a role in the development of secondary hyperparathyroidism in renal insufficiency. An increase in parathyroid hormone (PTH) levels is characteristic of patients with chronic renal failure. Increased levels of PTH can lead to osteitis fibrosa, a bone disease. A decrease in serum phosphorus may decrease serum PTH levels. Treatment of hyperphosphatemia includes reduction in dietary intake of phosphate, inhibition of intestinal phosphate absorption with phosphate binders, and removal of phosphate with dialysis. Sevelamer taken with meals has been shown to decrease serum phosphorus concentrations in patients with ESRD who are on hemodialysis. In vitro studies have shown that the capsule and tablet formulations bind phosphate to a similar extent. Sevelamer treatment also results in a lowering of low-density lipoprotein (LDL) and total serum cholesterol levels.

mechanism of action

Sevelamer prevents hyperphosphatemia by binding to dietary phosphate in the gut, preventing its absorption and thus decreasing serum parathyroid hormone levels.

toxicity

Sevelamer has been given to normal healthy volunteers in doses of up to 14 grams per day for eight days with no adverse effects. Sevelamer has been given in average doses up to 13 grams per day to hemodialysis patients. There are no reported overdosages of sevelamer in patients. Since sevelamer is not absorbed, the risk of systemic toxicity is low.

absorption

Not absorbed following oral administration, however no absorption studies have been performed in patients with renal disease.

drug interactions

Ciprofloxacin: Sevelamer decreases ciprofloxacin bioavailability

Cyclosporine: Sevelamer decreases the effect of cyclosporine

Trovafloxacin: Sevelamer may decrease the absorption of orally administered Trovafloxacin. The Sevelamer formulation contains iron that may intefere with Trovafloxacin absorption. Administer Trovafloxacin 2 hours before or 6 hours after the Sevelamer dose to minimize the interaction.