The “sliding scale” approach to phosphate binder dosing was discussed and challenged in a symposium presentation by Professor Rajnish Mehrotra at ASN Kidney Week 2014. Prof Mehrotra explained how increasing the dose of phosphate binders in response to uncontrolled serum phosphorus was not likely to be effective and that nephrologists should consider alternative strategies to achieve phosphate control.
Early in his presentation, Prof Mehrotra highlighted how nephrologists ask a lot of their patients, including multiple dialysis sessions per week, a wide range of dietary restrictions and a high medication burden. Against that backdrop, it is perhaps not surprising that dialysis patients do not follow all their nephrologist’s instructions, with low adherence to phosphate binders one of the more common issues. As we have discussed previously on COMPACT RENAL, there are many reasons behind non-adherence to medication, but high pill burden is a particular issue with phosphate binding therapy. Prof Mehrotra outlined how:
- The median pill burden in a dialysis patient is 19 per day, with 25% of patients prescribed 26 or more tablets.
- Phosphate binders constitute 51% of the pill burden in dialysis patients.
- Prescribing on a sliding scale to achieve phosphate control may not necessarily result in a higher dose, as a higher prescribed dose is associated with worse adherence.
- Even if patients do adhere, higher doses will lead to a lower self-reported quality of life, as well as potential adverse events from the therapies.
So what alternatives exist to dosing on a sliding scale? Prof Mehrotra outlined four strategies that can be used, ideally in combination, to achieve phosphate control without dose escalation:
- Preserve residual kidney function,
- Increase dialysis frequency and time,[3,4]
- Select more potent phosphate binders, and
- Judicious dietary choices.
As regards phosphate binder selection, reducing medication frequency is not an effective option, so physicians can consider using more potent drugs in order to achieve phosphate control. Prof Mehrotra highlighted data from 2011 which showed lanthanum carbonate and combinations of magnesium and calcium carbonate as having high binding potency.6 Newer data, not discussed by Prof Mehrotra, also shows that sucroferric oxyhydroxide is an active ingredient with high phosphate binding capacity.
Discussing dietary choices, the importance of dietary was emphasized with a specific focus on avoiding inorganic sources of phosphate and selecting foods with beneficial protein:phosphorus ratios.
In summary, Prof Mehrotra’s presentation challenged the conventional sliding scale approach to dose escalation and was a welcome reminder to the audience of the importance of a multi-strategy approach to phosphate control in dialysis patients.
See also the previous ASN 2014 article:
November 7th, 2014; ASN 2014 (Part 1) – Preview of ASN Kidney Week 2014
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2. Sedlacek M, Dimaano F, Uribarri J. Relationship between phosphorus and creatinine clearance in peritoneal dialysis: Clinical implications. Am J Kidney Dis. 2000;36(5):1020-1024. doi:10.1053/ajkd.2000.19105.
3. FHN. In-Center Hemodialysis Six Times per Week versus Three Times per Week. N Engl J Med. 2010;363(24):2287-2300. doi:10.1056/NEJMoa1001593.
4. Rocco MV, Lockridge RS, Beck GJ, et al. The effects of frequent nocturnal home hemodialysis: the Frequent Hemodialysis Network Nocturnal Trial. Kidney Int. 2011;80(10):1080-1091. doi:10.1038/ki.2011.213.
5. Fishbane S, Delmez J, Suki WN, et al. A Randomized, Parallel, Open-Label Study to Compare Once-Daily Sevelamer Carbonate Powder Dosing With Thrice-Daily Sevelamer Hydrochloride Tablet Dosing in CKD Patients on Hemodialysis. Am J Kidney Dis. 2010;55(2):307-315. doi:10.1053/j.ajkd.2009.10.051.
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7. Wilhelm M, Gaillard S, Rakov V, Funk F. The iron-based phosphate binder PA21 has potent phosphate binding capacity and minimal iron release across a physiological pH range in vitro. Clin Nephrol. 2014;81(04):251-258. doi:10.5414/CN108119.
8. Sullivan C, Sayre SS, Leon JB, et al. Effect of food additives on hyperphosphatemia among patients with end-stage renal disease: a randomized controlled trial. JAMA J Am Med Assoc. 2009;301(6):629-635. doi:10.1001/jama.2009.96.
9. Sherman RA, Mehta O. Dietary Phosphorus Restriction in Dialysis Patients: Potential Impact of Processed Meat, Poultry, and Fish Products as Protein Sources. Am J Kidney Dis. 2009;54(1):18-23. doi:10.1053/j.ajkd.2009.01.269.