Elucidation of Tartaric Acid-Assisted Supersaturation Maintenance of Dipyridamole by Eudragit® E100

Purpose The purpose of this study was to investigate the effect of tartaric acid on the maintenance of dipyridamole supersaturation using Eudragit E100 as a carrier. Methods The solubility of dipyridamole was determined in a buffer solution (pH = 6.8) containing Eudragit E100 and various concentrations of tartaric acid. Dissolution tests were conducted using a pH-shift method, transitioning from an acidic solution (pH = 1.2) to a buffer solution (pH = 6.8). The drug concentration in the buffer solution was measured to assess drug supersaturation. The dissolution behavior of binary and ternary combinations of dipyridamole, Eudragit E100, and tartaric acid was evaluated and compared. The interference of tartaric acid in the interaction between Eudragit E100 and dipyridamole was assessed using FT-IR and nuclear magnetic resonance (NMR) techniques. Results The addition of tartaric acid to Eudragit E100 exhibited a strong synergistic effect in stabilizing the supersaturation of dipyridamole. The results demonstrated that tartaric acid, by lowering the pH, increased the affinity of Eudragit E100 for dipyridamole, thereby enhancing its ability to maintain drug supersaturation. Conclusion The presence of acidifiers such as tartaric acid significantly improved the maintenance of drug supersaturation by Eudragit E100 due to the synergistic effect between Eudragit E100 and the acidifier.