Chewing Gum Aids Phosphate Control

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Used between meals to bind salivary phosphate, it may be a useful adjunct to sevelamer hydrochloride.

Adding salivary phosphate-binding chewing gum to traditional phosphate-binder therapy could improve hyperphosphatemia control in hemodialysis (HD) patients, data show.

Researchers noted that even with the use of phosphate binders, only about 50% of HD patients achieve serum phosphate levels recommended by the Kidney Disease Outcomes Quality Initiative guidelines. Previous research shows that salivary phosphate levels correlate with serum phosphate although salivary phosphate content is much higher than serum phosphate levels.

In a new study, Vincenzo Savica, MD, of the University of Messina in Italy, and colleagues tested a hypothesis that binding salivary phosphate during periods of fasting in addition to using phosphate binders with meals could improve hyperphosphatemia treatment.

Their study included 13 HD patients with serum phosphate levels above 6.0 mg/dL despite treatment with sevelamer hydrochloride. The investigators tested a newly formulated gum containing 20 mg of chitosan, a natural polymer shown to have phosphate-binding capability. They instructed patients to chew the gum between meals twice daily for two weeks in addition to adhering to their prescribed regimen of sevelamer hydrochloride.

By the end of week 2, salivary phosphate decreased 55% from baseline (from 73.21 to 33.19 mg/dL) and serum phosphate decreased 31% from baseline (7.6 to 5.25 mg/dL), according to a report in the Journal of the American Society of Nephrology (2009;20:639-644).

Salivary phosphate returned to baseline by day 15 following discontinuation of the chewing gum; serum phosphate levels took 30 days to return to baseline. The gum did not affect parathyroid hormone and serum calcium levels.

Although chitosan seems to affect salivary phosphate binding in the mouth acutely, the delayed recovery in serum phosphate merits further studies, the investigators stated. It is possible that when chitosan is solubilized in the stomach at acidic pH, it could be retained on the GI mucosa for a prolonged time, thus exerting further phosphate binding. The daily removal of an additional phosphate load from GI fluids could support sevelamer treatment, they noted.

The authors concluded that salivary phosphate binding could be a useful approach to the dietary management of serum phosphate level reduction in HD patients. Moreover, chewing the gum during fasting periods, as an add-on to taking phosphate binders during meals, appears to result in better hyperphosphatemia control.

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