Sevelamer Dosing for Hyperphosphatemia in Dialysis Patients
For patients with hyperphosphatemia on dialysis, sevelamer hydrochloride should be initiated at 800-1600 mg three times daily with meals, with dose titration by one tablet per meal every two weeks to achieve target serum phosphorus levels of 3.5-5.5 mg/dL. 1
Initial Dosing Algorithm
The FDA-approved dosing for sevelamer hydrochloride in dialysis patients is based on baseline serum phosphorus levels:
| Serum Phosphorus | Sevelamer Hydrochloride 800 mg | Sevelamer Hydrochloride 400 mg |
|---|---|---|
| >5.5 and <7.5 mg/dL | 1 tablet three times daily with meals | 2 tablets three times daily with meals |
| ≥7.5 and <9 mg/dL | 2 tablets three times daily with meals | 3 tablets three times daily with meals |
| ≥9 mg/dL | 2 tablets three times daily with meals | 4 tablets three times daily with meals |
Dose Titration
- Adjust dosage based on serum phosphorus concentration with a goal of lowering serum phosphorus to 5.5 mg/dL or less 1
- Increase or decrease by one tablet per meal at two-week intervals as necessary 1
- The average effective dose in clinical trials was approximately three 800 mg tablets per meal 1
- The maximum average daily dose studied was 13 g 1
Timing of Administration
- Sevelamer hydrochloride should be taken with meals to effectively bind dietary phosphate 2
- The general consensus is that phosphate binders should be taken 10-15 minutes before or during meals for optimal efficacy 3
Monitoring
- Monitor serum phosphorus levels every 2-4 weeks during dose titration, then monthly 2
- Monitor serum calcium levels, especially when switching from calcium-based binders 2
- The goal is to maintain serum phosphorus between 3.5-5.5 mg/dL 2
Patient Selection and Considerations
Sevelamer is particularly beneficial for:
- Patients with hypercalcemia (corrected serum calcium >10.2 mg/dL) 2
- Patients with low parathyroid hormone levels (<150 pg/mL) 2
- Patients with severe vascular or soft tissue calcifications 2
- Patients whose total elemental calcium intake from calcium-based binders exceeds 1,500 mg/day 2
Combination Therapy
- For patients who remain hyperphosphatemic despite maximum tolerated doses of sevelamer, combination therapy with calcium-based binders may be considered 2
- Total elemental calcium intake should not exceed 1,500 mg/day and total daily calcium intake should not exceed 2,000 mg/day 2
Common Side Effects and Management
- Most common adverse reactions include gastrointestinal symptoms: dyspepsia, diarrhea, nausea, vomiting, and constipation 1
- More serious but less common adverse events include dysphagia, bowel obstruction, and gastrointestinal ulcers 1
- In clinical studies, approximately 38% of patients discontinued sevelamer due to gastrointestinal side effects 4
Clinical Efficacy
Sevelamer has been shown to effectively reduce serum phosphorus levels in multiple studies:
- In a randomized crossover study, sevelamer demonstrated similar efficacy to calcium carbonate in reducing serum phosphorus (-3.3 mg/dL vs -3.9 mg/dL) but with significantly less hypercalcemia 5
- A 2014 randomized controlled trial showed that sevelamer carbonate significantly reduced serum phosphorus by 2.14 mg/dL compared to placebo 6
By following this dosing regimen and monitoring protocol, sevelamer can effectively control hyperphosphatemia in dialysis patients while minimizing the risks of hypercalcemia associated with calcium-based phosphate binders.