Introduction
Renvela (sevelamer carbonate) is a phosphate binder medication used to control serum phosphorus levels in patients with chronic kidney disease (CKD) on dialysis. It belongs to a class of non-calcium, non-aluminum phosphate binders that work by binding dietary phosphate in the gastrointestinal tract.
Mechanism of Action
Sevelamer carbonate is a polymeric amine that binds phosphate through ion exchange and hydrogen bonding in the gastrointestinal tract. Unlike calcium-based binders, it does not contribute to calcium absorption. The drug forms insoluble complexes with phosphate ions from dietary sources, preventing their absorption and facilitating fecal elimination. This mechanism helps reduce serum phosphate levels without adding calcium load to the body.
Indications
- Control of serum phosphorus in patients with chronic kidney disease on hemodialysis
- Control of serum phosphorus in patients with chronic kidney disease on peritoneal dialysis
- Not indicated for use in patients not on dialysis or for prevention of renal osteodystrophy
Dosage and Administration
Initial dose: 800-1600 mg with each meal based on serum phosphorus levels Titration: Adjust by 400-800 mg per meal at 2-week intervals as needed Maximum dose: 13 grams per day (clinical experience limited beyond this dose) Administration: Tablets should be taken with meals; do not crush, break, or chew tablets Special populations:- Pediatric patients: Safety and efficacy established for ages 6-17 years
- Geriatric patients: No dosage adjustment required
- Hepatic impairment: No specific recommendations
- Renal impairment: Specifically designed for patients with renal impairment on dialysis
Pharmacokinetics
Absorption: Not absorbed systemically; acts locally in the gastrointestinal tract Distribution: Confined to the gastrointestinal lumen Metabolism: Not metabolized systemically Elimination: Excreted unchanged in feces Protein binding: Not applicable due to lack of systemic absorptionContraindications
- Hypersensitivity to sevelamer carbonate or any component of the formulation
- Bowel obstruction
- Hypophosphatemia
- Fecal impaction (relative contraindication)
Warnings and Precautions
- May cause constipation, which could lead to bowel obstruction, perforation, or fecal impaction
- Use with caution in patients with swallowing disorders, severe gastrointestinal motility disorders, or major gastrointestinal surgery
- May reduce the absorption of concomitantly administered oral medications
- Monitor for signs and symptoms of vitamin deficiencies (A, D, E, K, and folic acid) with long-term use
- Not recommended for use in patients not on dialysis
Drug Interactions
Clinically significant interactions:- Oral medications: Separate administration by at least 1 hour before or 3 hours after Renvela
- Specifically affects absorption of:
- Ciprofloxacin (reduced bioavailability by approximately 50%) - Mycophenolate mofetil (reduced MPA exposure by 25-30%) - Thyroid hormones (monitor TSH levels closely) - Fat-soluble vitamins (A, D, E, K) - Antifungal agents (azole class)
Adverse Effects
Common adverse effects (≥5%):- Constipation (22%)
- Diarrhea (19%)
- Dyspepsia (16%)
- Nausea (14%)
- Abdominal pain (12%)
- Vomiting (9%)
- Bowel obstruction
- Intestinal perforation
- Fecal impaction
- Severe hypophosphatemia
- Vitamin deficiencies
Monitoring Parameters
- Serum phosphorus levels (monthly initially, then quarterly when stable)
- Serum calcium levels
- Serum bicarbonate and chloride levels (may cause metabolic acidosis)
- Vitamin levels (A, D, E, K) with long-term therapy
- Bowel function and symptoms of constipation
- Signs and symptoms of gastrointestinal obstruction
- Nutritional status
Patient Education
- Take with meals and snacks as directed
- Swallow tablets whole; do not crush, break, or chew
- Maintain adequate fluid intake to prevent constipation
- Report severe constipation, abdominal pain, or difficulty swallowing immediately
- Separate other medications by at least 1 hour before or 3 hours after Renvela
- Follow prescribed dietary restrictions for phosphorus control
- Regular follow-up with healthcare provider for monitoring
- Report any signs of vitamin deficiency (vision changes, bleeding tendencies, bone pain)
References
1. FDA Prescribing Information: Renvela (sevelamer carbonate) 2. National Kidney Foundation. KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update. Am J Kidney Dis. 2020;76(3 Suppl 1):S1-S107 3. Block GA, et al. Mineral metabolism, mortality, and morbidity in maintenance hemodialysis. J Am Soc Nephrol. 2004;15(8):2208-2218 4. Qunibi WY, et al. A randomized, double-blind, placebo-controlled trial of sevelamer carbonate in CKD patients on hemodialysis. Nephrol Dial Transplant. 2011;26(6):1948-1958 5. Tonelli M, et al. Oral phosphate binders in patients with kidney failure. N Engl J Med. 2010;362(14):1312-1324 6. ClinicalTrials.gov: Safety and efficacy studies of sevelamer carbonate 7. KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD)