Reducing the Sublimation Tendency of Ligustrazine through Salt Formation

Two new salts of ligustrazine (tetramethylpyrazine, TMP) with the sweeteners saccharine (SAC) and acesulfame (ACS) have been synthesized through the anion exchange reaction. Single crystals of the new forms were prepared, and their structures were determined. The stability of the new salts against heat and humidity was tested and compared to the commercial hydrochloride and phosphate salts. The sublimation kinetics at various temperatures was analyzed using the Arrhenius equation. The results indicated that TMP-ACS exhibits significantly reduced sublimation tendency and hygroscopicity, which make it a more suitable salt for developing a tablet with acceptable shelf stability than the salts currently used in commercial products.