Solubility of valdecoxib in the presence of ethanol and sodium lauryl sulfate at (298.15, 303.15, and 308.15) K

This study investigated the solubilization of valdecoxib in aqueous solution using ethanol as a cosolvent and sodium lauryl sulfate as a surfactant at (298.15, 303.15, and 308.15) K. The analysis of valdecoxib is carried out by UV spectral measurements at a lambda(max) value of 201 nm. Preliminary investigations indicated both ethanol and sodium lauryl sulfate are respectively an effective cosolvent and surfactant for the solubilization of valdecoxib. The aqueous solubility of valdecoxib could be enhanced significantly by using ethanol as a cosolvent at various concentrations as well as by increasing the temperature of the dissolution media. The solubility of valdecoxib increased with increasing mass fraction of ethanol up to 80%, but solubility decreased in pure ethanol at all the temperatures. Experimental solubility data of valdecoxib were correlated with those calculated by a log-linear equation. Calculated Gibbs free energy values were all negative for all the ethanol + water mixtures at (298.15, 303.15, and 308.15) K, indicating the spontaneous nature of valdecoxib solubilization. In the case of sodium lauryl sulfate + water mixtures, the solubility of valdecoxib linearly increased with increasing mass fraction of sodium lauryl sulfate in water at all the temperatures.