Experimental measurement and thermodynamic modeling of solubility of Riluzole drug (neuroprotective agent) in supercritical carbon dioxide

Experimental measurement of solubility data is framework for nanoparticle synthesis using supercritical fluid (SCF) technology. Accordingly, the solubility of Riluzole (RLZ) as a neuroprotective agent, in supercritical carbon dioxide (SC-CO2), was measured at various temperatures and pressures, for the first time, for modeling and correlating of new experimental data through different methods to evaluate their abilities. Solubility data measured from the static process range from 4.95 x 10-5 to 1.49 x 10-4 (mole fraction). To correlate the solubility data, three thermodynamic models of (1) eight density-based correlations, (2) two equations of state (EoSs), and (3) COSMO-Vacancy (Vac) activity coefficient were used. Empirical models of Jouyban and Bian presented the best correlation Combining SRK and PR EoSs separately with Wilson activity coefficient by means of Wong Sandler (WS) mixing rule with three curve-fitting parameters, illustrated an excellent fit with the experimental data by AARD%, 5.0 and 7.0%, respectively. Afterward, solid-liquid equilibrium for RLZ+SC-CO2 system was considered by COSMO-Vac model via conductor like screening model theory. Using quantum computational solvation calculation, the average logarithmic deviation was smaller than unity (0.42) which indicate the suitability of the model without considering the adjustable parameter. Finally, thermodynamic enthalpies of RLZ was calculated for the first time.

Automated summary

This study measured the solubility of Riluzole in supercritical carbon dioxide for the first time and evaluated the data using various methods and models. The results showed that the models used provided a good fit to the experimental data and were suitable for correlating solubility.