Enhancement of the dissolution profile of diclofenac sodium using ionic liquid-based formulations

Purpose: To investigate the dissolution profile of ionic liquid forms of diclofenac sodium. Methods: Three ionic liquids, namely 1-butyl-3-methylimidazolium chloride, cholinium chloride, and benzalkonium chloride, were converted into corresponding diclofenac-ionic liquid formulations by reacting each ionic liquid with diclofenac sodium at a 1.1:1 molar ratio. The prepared diclofenac-ionic liquids were solidified by adsorption onto microcrystalline cellulose (Avicel PH-102) and characterized using Fourier-transform infrared spectroscopy, powder X-ray diffraction, and differential scanning calorimetry to prove ionic interactions as well as partial amorphization of the diclofenac. Results: Percentage yield of the prepared ionic formulations was > 94 %. There was significant improvement in solubility, with the imidazolium diclofenac ionic liquid exhibiting a 5.3-fold and 4-fold increase in solubility in distilled water and phosphate buffer (pH 6.8), respectively (p < 0.05). In addition, the imidazolium diclofenac-ionic liquid showed an excellent dissolution profile. Conclusion: These results highlight the potential applicability of imidazolium diclofenac ionic liquid as an efficient dissolution rate enhancer for diclofenac. This study justifies applying ionic liquids as recovery-enhancing carriers in drug delivery systems, especially for poorly soluble drugs.