Tooth gel with 22500ppm fluorine (= 5% NaF). However, this 5% NaF is insoluble in water.

A prescription from a physician for a 22500ppm fluor tooth gel without further requirements. However, after search and test preparations, it is determined that 22500ppm (= 5% NaF) does not dissolve in the amount of water. The solubility of NaF is 1 part on 25 parts so only 4%. Is there an option to process 22500ppm Fluor in a gel anyway? In other words: does a ' suspension ' gel ' exist ' or will adding for example glycerol increase the solubility sufficiently? Or will another concentration/dosage form be chosen?