Promotion of mefenamic acid nucleation by a surfactant additive, docusate sodium

The influence of docusate sodium (DOSS) on the nucleation of mefenamic acid (MEF) has been studied in different dimethylacetamide (DMA)–water mixtures. A series of induction time experiments were conducted under moderate supersaturations, varying the solvent composition and the concentration of DOSS. In 40% DMA–60% water, the presence of 0.1 and 0.2 mg/mL DOSS increased the nucleation rate. Evaluating the results by the classical nucleation theory reveals that the pre-exponential factor (A) increases by approximately 50% while the interfacial energy is essentially uninfluenced. It is also found that the crystal growth rate becomes higher in the presence of DOSS. It is thus hypothesized that transport and desolvation of MEF molecules are facilitated in the presence of DOSS. With increasing amount of DMA in the binary solvent mixture, the influence of DOSS appears to decrease.