Compatibility of risedronate sodium tablets with food thickeners

The chemical compatibility of commercially available food thickeners used with risedronate sodium tablets is examined.

Plastic 250-mL disposable beakers were used to prepare solutions for compatibility testing. Two ounces of purified water at room temperature was added to each beaker. One risedronate sodium 35-mg tablet was also added to each beaker and allowed to disintegrate without agitation. After two minutes, the water was stirred with a plastic spoon and an additional 4 oz of water was added to each beaker and stirred briskly for 30 seconds. The recommended amount of each food thickener was then added to each beaker. The control solution contained a tablet in water but no food thickener. Immediately after preparation, a portion of each solution was filtered through a 0.2-microm filter and assayed by high-performance liquid chromatography (HPLC). The solutions sat for 1 hour at room temperature and then were stirred briskly for 30 seconds, filtered, and assayed by HPLC. They then sat for 24 hours at room temperature and then were stirred briskly again for 30 seconds, filtered, and assayed by HPLC.

The risedronate tablets alone showed a mean initial concentration of 0.194 mg/mL and a mean recovery of 99.8% after 1 hour and 99.2% after 24 hours. The mean initial concentration for risedronate sodium in each of the five food thickeners ranged from 0.193 to 0.195 mg/mL. All samples ranged from 98.8% to 99.9% of the initial concentration after 1 hour and from 96.7% to 99.2% after 24 hours.

Risedronate sodium tablets were compatible for 24 hours with five food thickeners.