Sodium Hydroxide → Phosphate

Participants

Reaction Steps

3.25 g of sodium alendronate trihydrate and 1.42 g of dibasic sodium phosphate (anhydrous) were dissolved in 100 mL water. The solution temperature was kept at 50° C. on a hot plate. This temperature was maintained throughout the process. While stirring, a solution of 5.8 g of zinc acetate dihydrate in 50 mL of water was added to the alendronate-phosphate solution. The pH of the solution was kept at 7.4 by adding sodium hydroxide solution simultaneously until all the zinc acetate solution was added. The precipitate was collected by filtration and washed with water. The solid was then dried at 120° C. overnight. 5.28 g of zinc complex salt of alendronate and phosphate with a molecular ratio of 1:1 was thus obtained. The solubility of the API (as alendronic acid) in saline at room temperature for this complex is 2.4 mcg/mL, i.e. 0.00024%. It also has a very low solubility of the API.

Provenance & Evidence