Chewing Chitosan-Loaded Gum Reduces Phosphate Levels in ESRD Patients

Barbara Boughton

February 16, 2009

February 16, 2009 — Chewing chitosan-loaded gum twice daily can significantly decrease salivary phosphate and serum phosphate levels in hemodialysis patients and may help improve treatment for hyperphosphatemia, according to a preliminary study published in the March issue of the Journal of the American Society of Nephrology.

Hyperphosphatemia is known to contribute to vascular calcification and cardiac mortality, but only half of hemodialysis patients currently maintain the recommended levels for serum phosphate. The researchers hypothesized that the chitosan-loaded gum, which binds to salivary phosphate and was used in the study for 13 patients during periods of fasting, might help decrease both serum and salivary phosphate levels. The result might then be improved control of hyperphosphatemia and thus decreased cardiovascular risk.

“The results of our study suggest that salivary PO4 binding could be a useful approach to the dietary management of serum PO4 level reduction in HD (hemodialysis) patients and that chewing sessions in fasting periods, as an add-on to phosphate binders at meals, leads to a better control of hyperphosphatemia,” Vincenzo Savica, MD, from the Department of Nephrology and the Nephrology and Dialysis Units, Papardo Hospital, Messina, Italy, and colleagues report in the study.

“Given the importance of hyperphosphatemia in the high morbidity and mortality of patients with [end-stage renal disease], the requirement to achieve neutral PO4 balance by means of different PO4 binders with different mechanisms of action could be helpful to improve patient compliance and reduce pill burden,” the authors write.

In the study, 13 patients with serum phosphate levels higher than 6.0 mg/dL were asked to chew 20 mg of the chitosan-loaded chewing gum twice daily for 2 weeks between meals. All patients were also treated with sevelamer hydrocholoride and were placed on a diet with a protein content of 1.2 g/kg per day. The open study enrolled patients who were undergoing hemodialysis 3 times per week for a year or more. The effects of the chewing gum regimen on salivary and serum phosphate levels were evaluated for 6 weeks after the study began.

Results revealed that salivary phosphate and serum phosphate decreased significantly after 1 week of chewing the chitosan-loaded gum, and even more after 2 weeks. At week 1, the patients’ salivary phosphate levels had decreased from 73.21 to 52.02 mg/dL (P < .01), and serum levels decreased from 7.60 to 5.38 mg/dL (P < .00001). After 2 weeks, salivary phosphate levels were reduced to 33.19 mg/dL (P < .00001) and serum levels decreased to 5.25 mg/dL (P < .00001). After discontinuing the chewing gum regimen, it took 15 days for patient salivary phosphate to return to baseline levels, but 30 days for serum phosphate to return to levels seen at the study’s initiation. No patients reported adverse events from the chewing gum.

While parathyroid hormone and serum calcium concentrations were not significantly changed by chewing the chitosan gum, there was a trend toward declining parathyroid hormone levels throughout the study. Since hyperphosphatemia influences parathryroid hormone synthesis and secretion, further studies on this effect in larger studies could clarify the biological action of the chitosan chewing gum, the authors write.

The investigators conclude that their observations are preliminary and need to be confirmed by a randomized, double-blind placebo-controlled clinical trial with a larger hemodialysis patient population. Yet they note that the study offers hope for an additional way to treat hyperphosphatemia and its associated cardiovascular risk. “Adding salivary phosphate binding to traditional phosphate binders could be a useful approach for improving treatment of hyperphosphatemia in hemodialysis patients,” they write.

J Am Soc Nephrol. 2009;20:639–644.


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