Dr. Mujtaba Hasnain, from Newark Beth Israel Medical Center, Newark, New Jersey, discusses his abstract for the National Kidney Foundation’s 2015 Spring Clinical Meetings (SCM15), Chitosan; A Novel Salivary Phosphorous Binder, with Dr. Kenar Jhaveri, AJKD Blog Editor.
AJKDblog: Why don’t you tell us a little about your research and abstract being presented at the NKF 2015 Spring Meetings?
In uremic patients, hyperphosphatemia is associated with cardiovascular calcification and increased cardiovascular mortality. Despite the use of phosphate binders, only half of hemodialysis (HD) patients achieve recommended serum phosphate levels. A hyperphosphoric salivary content, which correlates linearly with serum phosphate, has been reported in HD patients.
A 46-year-old woman presented for routine monthly follow up in peritoneal dialysis (PD) clinic. She was on peritoneal dialysis for the last 3 years. Her clearance was excellent (Kt/V 2.2) on continuous ambulatory peritoneal dialysis. Her serum calcium, PO4 and intact parathyroid hormone (iPTH) levels were 12 mg/dL, 7.0 mg/dL and 1117 pg/mL respectively. She has been non-adherent with low PO4 diet and refused to take all types of phosphate binders and sensipar due to unclear allergic reactions. She presented again one month later for routine follow up while maintained on same prescription of PD. Her laboratory data showed serum calcium of 12.1 mg/dL, while serum PO4 and iPTH levels improved to 6.7 mg/dL and 871 pg/mL respectively. On further questioning it was revealed that she started taking herbal capsules three weeks prior for weight loss. We requested that the patient to bring in those herbal capsules. We investigated it further and found “chitosan” in those capsules. This “chitosan” is an excellent phosphate binder in saliva. Further double blind, controlled trials are required to assess its precise efficacy and side effect profile. It can potentially help hundreds of thousands of dialysis patients whose serum phosphorous levels fall out of recommended levels.
AJKDblog: How does chitosan work as a potential binder?
Chitosan is an abundant natural polymer that is produced by the deacetylation of chitin obtained from crustacean shells. Its structure is similar to cellulose and is not cleaved by digestive enzymes. It has been used as a dietary fiber for weight reduction and hyperlipidemia. In HD patients, with high salivary PO4 content and average daily salivary production of 500 mL, a conservative estimate of at least 366 mg of bioavailable phosphate daily entering the gastrointestinal fluid could be proposed. Chitosan is an active salivary phosphate binder especially when chewed as a gum for prolonged time periods. It doesn’t need to be given with food which is a limitation with other binders; instead, it can be used in fasting periods.
AJKDblog: The improvement of phosphate levels in your patient appears very mild? Was the trend of phosphate over time downtrending on this agent?
Based on few trials which are available to date, it works very effectively if chewed as a gum. Initially, the drop in serum phosphate was less significant but the trend afterwards was more promising. This patient was taking herbal capsules which is potentially less efficacious in binding phosphate as compared to chewing gum for little extended time period. This might be the reason for milder drop of serum phosphate in our patient.
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